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Fermentation, Volume 9, Issue 4 (April 2023) – 90 articles

Cover Story (view full-size image): Table olives are one of the most popular fermented foods in the Mediterranean area, with great global socioeconomic impact. To obtain a safe and stable final product, the use of starter cultures is strongly recommended for their production at an industrial scale. Nowadays, culture-independent techniques are widely applied to identify and track microbial starter cultures as well as their dynamics throughout fermentation. In the present study, the safety and stability of Sicilian table olives were determined through both plate count and quantitative real-time PCR (qPCR) approaches. The data demonstrated that qPCR is a promising tool with which to detect and quantify lactobacilli, used as starter cultures, which could be considered as a positive biomarker of stable table olive fermentation. View this paper
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3 pages, 187 KiB  
Editorial
Anaerobic Fermentation—A Biological Route towards Achieving Net Neutrality
by Sanjay Nagarajan
Fermentation 2023, 9(4), 404; https://doi.org/10.3390/fermentation9040404 - 21 Apr 2023
Viewed by 1041
Abstract
Increasing greenhouse gas levels have led to the international community pledging to curb the mean global temperature increase to less than 1.5 C. [...] Full article
14 pages, 1536 KiB  
Article
Dynamics of Microbial Communities in Nitrite-Free and Nutritionally Improved Dry Fermented Sausages
by Núria Ferrer-Bustins, Belén Martín, Mar Llauger, Ricard Bou, Sara Bover-Cid and Anna Jofré
Fermentation 2023, 9(4), 403; https://doi.org/10.3390/fermentation9040403 - 21 Apr 2023
Cited by 5 | Viewed by 1724
Abstract
Dry fermented sausage innovation trends are linked to consumer preferences for clean label and sodium-reduced foods. This study aims to evaluate the effect of the formulation and production process temperature on the dynamics of bacterial communities in fuet-type dry fermented sausages using metataxonomics. [...] Read more.
Dry fermented sausage innovation trends are linked to consumer preferences for clean label and sodium-reduced foods. This study aims to evaluate the effect of the formulation and production process temperature on the dynamics of bacterial communities in fuet-type dry fermented sausages using metataxonomics. Six fuet batches were manufactured, including formulations without and with the addition of nitrifying salts (replaced or not by pork liver auto-hydrolysate as a colouring agent), processed at 3 to 12 °C, and a partial replacement of NaCl by KCl, processed at 12 °C. Fermentation was performed spontaneously or by a starter culture. Physicochemical characterisation and culture-dependent and independent bacterial analyses were performed at day 0, 4 and 12, at the end of ripening (aw < 0.90) and after storage. Temperature was the most important factor determining the change in pH, aw and lactic acid bacteria levels while the presence of a starter culture promoted a pH decrease. Metataxonomic analysis showed that low temperature processes and the absence of nitrifying salts allowed the growth of spoilage-related species, while sausages submitted to a mild temperature containing a starter culture and nitrifying salts showed less bacterial diversity. Liver auto-hydrolysate added putative probiotic species to the product. This study provides valuable information to manufacturers who want to innovate safely. Full article
(This article belongs to the Special Issue Perspectives on Microbiota of Fermented Foods)
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18 pages, 6756 KiB  
Article
Biodiversity of Lactic Acid Bacteria in Traditional Fermented Foods in Yunnan Province, China, and Comparative Genomics of Lactobacillus plantarum
by Hong Li, Jiang Zhu, Yue Xiao, Shiyao Zhang, Yuwei Sun, Zhijia Liu, Chuanqi Chu, Xiaosong Hu and Junjie Yi
Fermentation 2023, 9(4), 402; https://doi.org/10.3390/fermentation9040402 - 20 Apr 2023
Cited by 6 | Viewed by 2263
Abstract
The diversity of lactic acid bacteria (LAB) in fermented foods in Yunnan currently lacks large-scale and systematic research. A total of 638 fermented foods were collected from 84 regions in Yunnan for diversity analyses. The results show that the dominant strains in various [...] Read more.
The diversity of lactic acid bacteria (LAB) in fermented foods in Yunnan currently lacks large-scale and systematic research. A total of 638 fermented foods were collected from 84 regions in Yunnan for diversity analyses. The results show that the dominant strains in various types of fermented foods were different. Additionally, the majority of the LAB were better adapted to regions with a temperature of 15–20 °C and a humidity of 64–74%. Lactobacillus plantarum (L. plantarum) was the most abundant of all the strains and was widely distributed in the 84 regions. Genetically, the guanine plus cytosine (GC) content of L. plantarum ranged from 35.60% to 47.90%, with genome sizes from 2.54 Mb to 5.76 Mb. A phylogenetic analysis revealed that the habitat source and geographic origin had little influence on the homologous genes of L. plantarum. The genetic diversity of L. plantarum was mostly represented by functional genes and carbohydrate utilization. This research provides valuable insights into the microbiota of different types of fermented foods in Yunnan. Meanwhile, a genetic diversity analysis of L. plantarum may help us to understand the evolutionary history of this species. Full article
(This article belongs to the Special Issue Microbial Resources and Health Effects of Traditional Fermented Food)
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15 pages, 1329 KiB  
Article
Bioaugmentation Strategies for Enhancing Methane Production from Shrimp Processing Waste through Anaerobic Digestion
by Valentina Mazzurco Miritana, Alessia Gaetani, Antonella Signorini, Antonella Marone and Giulia Massini
Fermentation 2023, 9(4), 401; https://doi.org/10.3390/fermentation9040401 - 20 Apr 2023
Cited by 3 | Viewed by 1989
Abstract
Bioaugmentation strategies were tested to improve energetic valorization of shrimp processing waste (SPW) by anaerobic digestion (AD). A fermenting bacteria pool (F210) obtained from coastal lake sediments and two strains of anaerobic fungi (AF), Orpynomyces sp. and Neocallimastix sp., commonly found as components [...] Read more.
Bioaugmentation strategies were tested to improve energetic valorization of shrimp processing waste (SPW) by anaerobic digestion (AD). A fermenting bacteria pool (F210) obtained from coastal lake sediments and two strains of anaerobic fungi (AF), Orpynomyces sp. and Neocallimastix sp., commonly found as components of microbial community of AD plants, were used with the aim of improving the fermentative and hydrolytic phases of AD, respectively. The experiment was carried out by testing single bioaugmentation at an SPW concentration of 6.5 gVS L−1 and combined bioaugmentation at three SPW concentrations (6.5, 9.7 and 13.0 gVS L−1, respectively), in batch mode and mesophilic conditions. Cumulative CH4 productions were higher in the combined bioaugmentation tests and increased in line with SPW concentration. The F210 played a key role in enhancing CH4 production while no effect was attributable to the addition of AFs. The CH4 content (%) in the biogas increased with substrate concentrations, with average values of 67, 70, and 73%, respectively. Microbial community abundance increased in line with the SPW concentration and the acetoclastic Methanosarcina predominated within the methanogen Archaea guild in the combined bioaugmentation test (in all cases > 65%). Full article
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17 pages, 3097 KiB  
Article
Improving Pulping Performance as Well as Reducing Consumption and Increasing Efficiency via Microbial Consortium Pretreating Bamboo
by Chun Liu, Zhijian Li, Xiuqiong Guan, Yang Xu, Nan Huang and Kui Liu
Fermentation 2023, 9(4), 400; https://doi.org/10.3390/fermentation9040400 - 20 Apr 2023
Cited by 1 | Viewed by 1583
Abstract
The bio-refining process of bamboo is more challenging compared to wood due to its dense and stabilized complex polymer structure, as well as its abundance of degradation-resistant components. Consequently, the bio-refining of bamboo requires more energy and time consumption compared to the bio-refining [...] Read more.
The bio-refining process of bamboo is more challenging compared to wood due to its dense and stabilized complex polymer structure, as well as its abundance of degradation-resistant components. Consequently, the bio-refining of bamboo requires more energy and time consumption compared to the bio-refining of wood. In this study, co-cultured microorganisms were utilized for the pretreatment of bamboo to improve pulping performance, reduce consumption, and increase efficiency. These microorganisms were constructed by combining environmental microorganisms found in bamboo pulp with Bacillus sp. that were self-screened. The results of 16S rRNA analysis showed that the genera Proteobacteria, Firmicutes, Bacteroidota, and Actinobacteriota gradually became dominant during the treatment process. Additionally, the PICRUSt results indicated that the co-culture microbial consortium C strategy strengthened key enzyme activities related to the degradation of bamboo lignocelluloses. The microbial consortium pretreatment resulted in removing lignin and hemicellulose at rates of 21.96% and 26.21%, respectively. This process also caused a decrease in the crystalline index, indicating the presence of disordered crystalline regions. This change was beneficial for the subsequent Kraft pulping process. Compared to the conventional bamboo pulp, the yield of pretreated bamboo pulp increased slightly, while the cellulose purity and paper properties were significantly superior. The obtained Kraft pulp, which underwent microbiological pretreatment, met the requirements for superior Kraft pulp products despite a 65 min decrease in cooking time and a 10 °C decline in maximum cooking temperature. This study proves that co-cultured microbial consortium used for pretreating bamboo are beneficial for bamboo Kraft pulping. This approach can be considered environmentally friendly and leads to energy saving and cost reduction in bamboo bio-refining processes. Full article
(This article belongs to the Special Issue Biorefinery of Lignocellulosic Biomass)
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18 pages, 7386 KiB  
Article
Effect of Pretreatments on the Production of Biogas from Castor Waste by Anaerobic Digestion
by Diana Laura Quezada-Morales, Juan Campos-Guillén, Francisco Javier De Moure-Flores, Aldo Amaro-Reyes, Juan Humberto Martínez-Martínez, Ricardo Chaparro-Sánchez, Carlos Eduardo Zavala-Gómez, Antonio Flores-Macías, Rodolfo Figueroa-Brito, José Alberto Rodríguez-Morales and Miguel Angel Ramos-López
Fermentation 2023, 9(4), 399; https://doi.org/10.3390/fermentation9040399 - 20 Apr 2023
Cited by 4 | Viewed by 1682
Abstract
Lignocellulosic biomass is a source of carbohydrates that can be used in the production of biogas. The aim of this study was to obtain biogas from biomass waste (leaves, stems and seed bagasse) of Ricinus communis, applying pretreatments such as temperature and [...] Read more.
Lignocellulosic biomass is a source of carbohydrates that can be used in the production of biogas. The aim of this study was to obtain biogas from biomass waste (leaves, stems and seed bagasse) of Ricinus communis, applying pretreatments such as temperature and humidity. We examined the effect of these pretreatments on the biomass, two enzymatic pretreatments (cellulase and cellobiohydrolase), two chemicals (NaOH and HCl) and two controls (dried castor straw and seed bagasse) on the methane content. The experiment was performed in two anaerobic digestion (AD) assays at a controlled temperature (37 °C) and at room temperature, with a hydraulic retention time (HRT) of 55 days. The results showed that the residues of the seed bagasse produced the highest biogas yields both at room temperature and at the controlled temperature since this material at 37 °C produced 460.63 mL gVS−1 under cellulase pretreatment; at room temperature, the highest level of production was found for the control (263.41 mL gVS−1). The lowest yields at the controlled temperature and room temperature were obtained from residues of Ricinus communis treated with cellobiohydrolase and the seed bagasse treated with alkaline (15.15 mL gVS−1 and 78.51 mL gVS−1, respectively). Meanwhile, the greatest amount of methane was produced by seed bagasse treated with cellobiohydrolase at a controlled temperature (92.2% CH4) and the lowest content of CH4 (15.5%) was obtained at a controlled temperature from castor straw under the control treatment. Full article
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14 pages, 3132 KiB  
Article
Enhanced Pentostatin Production in Actinomadura sp. by Combining ARTP Mutagenesis, Ribosome Engineering and Subsequent Fermentation Optimization
by Hongyu Zhang, Deguang Zhang, Ran Liu, Tingting Lou, Ruyue Tan and Suying Wang
Fermentation 2023, 9(4), 398; https://doi.org/10.3390/fermentation9040398 - 20 Apr 2023
Cited by 1 | Viewed by 1538
Abstract
The special structure of pentostatin causes it to possess a wide spectrum of biological and pharmacological properties, and it has been extensively employed to treat malignant tumors and is the first-line treatment for hairy cell leukemia. Pentostatin is mainly distributed in several actinomycetes [...] Read more.
The special structure of pentostatin causes it to possess a wide spectrum of biological and pharmacological properties, and it has been extensively employed to treat malignant tumors and is the first-line treatment for hairy cell leukemia. Pentostatin is mainly distributed in several actinomycetes and fungi species. However, its low titer in microbes is not able to meet medical needs. Here, we report a strain improvement strategy based on combined atmospheric and room-temperature plasma (ARTP) mutagenesis and ribosome engineering screening, as well as fermentation optimization, for enhanced pentostatin production. The original strain, Actinomadura sp. ATCC 39365, was treated with ARTP and screened by ribosome engineering to obtain one stable pentostatin high-yield mutant Actinomadura sp. S-15, which produced 86.35 mg/L pentostatin, representing a 33.79% increase compared to Actinomadura sp. ATCC 39365. qRT-PCR analysis revealed that pentostatin biosynthesis-related gene expression was significantly upregulated in Actinomadura sp. S-15. Then, to further enhance pentostatin production, the fermentation medium was optimized in flask culture and the pentostatin production of Actinomadura sp. S-15 reached 152.06 mg/L, which is the highest pentostatin production reported so far. These results demonstrate the effectiveness of combined ARTP mutation, ribosome engineering screening, and medium optimization for the enhancement of pentostatin production, and provide a methodology enabling the sustainable production of pentostatin on an industrial scale. Full article
(This article belongs to the Special Issue Pharmaceutical Fermentation: Antibiotic Production and Processing)
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18 pages, 2561 KiB  
Article
Identification of a Strain Degrading Ammonia Nitrogen, Optimization of Ammonia Nitrogen Degradation Conditions, and Gene Expression of Key Degrading Enzyme Nitrite Reductase
by Zhenhao Wang, Huijing Liu and Tangbing Cui
Fermentation 2023, 9(4), 397; https://doi.org/10.3390/fermentation9040397 - 20 Apr 2023
Cited by 1 | Viewed by 1878
Abstract
In recent years, nitrogen pollutants have become one of the main causes of water pollution and eutrophication; thus, it is very important to increase the research on nitrogen removal in wastewater. In this study, a bacterium with outstanding ammonia nitrogen degradation capability was [...] Read more.
In recent years, nitrogen pollutants have become one of the main causes of water pollution and eutrophication; thus, it is very important to increase the research on nitrogen removal in wastewater. In this study, a bacterium with outstanding ammonia nitrogen degradation capability was isolated from piggery wastewater and identified as Bacillus tequilensis (designated as A2). The ammonia nitrogen degradation rate of A2 reached the highest level (95%) when the incubation temperature was 42 °C, the initial pH was 7, the seed volume was 5%, the rotation speed was 160 r·min−1, the C/N was 10:1, and the carbon source was sodium citrate. A new nitrite reductase gene was successfully expressed in E. coli BL21 (DE3), and the result showed that the enzyme gene contained 2418 bp and 805 encoding amino acids, the recombinant enzyme was purified through an Ni2+ affinity chromatography column, it had a molecular weight of about 94 kDa, it displayed the maximum enzyme activity at 40 °C and pH 6.0, it exhibited good stability in the range of 25 °C to 35 °C, and it showed a pH of 6.0 to 7.0. A 1 mM concentration of Fe3+ promoted the enzyme activity, followed by a 1 mM concentration of Fe2+ and Mg2+. The kinetic parameters of Km, Kcat, and the Vmax of NiR-A2 were calculated to be 1.37 μmol·mL−1, 4.9 × 102 s−1, and 23.75 μmol·mg−1·min−1, respectively. This strain shows good prospects for wastewater treatment, especially in the treatment of high concentration ammonia nitrogen and nitrite degradation, because of its tolerance to and high degradation rate of high concentrations of ammonia nitrogen and high nitrite. Full article
(This article belongs to the Section Microbial Metabolism, Physiology & Genetics)
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17 pages, 5595 KiB  
Article
Transcriptomics-Guided Investigation of the SLCG_Lrp Regulon Provides New Insights into Its Role for Lincomycin Biosynthesis
by Yurong Xu, Wanlian Xu, Jing Yi, Binglin Li, Meng Liu, Maifei Zhang, Yang Zheng, Ruihua Liu, Hang Wu and Buchang Zhang
Fermentation 2023, 9(4), 396; https://doi.org/10.3390/fermentation9040396 - 19 Apr 2023
Cited by 3 | Viewed by 1215
Abstract
Lincomycin industrially produced by Streptomyces lincolnensis can be adopted to treat infections caused by Gram-positive bacteria. SLCG_Lrp, a transcriptional regulator of the Lrp family, was first identified to positively regulate lincomycin biosynthesis. However, the regulatory role of SLCG_Lrp is yet to be elucidated. [...] Read more.
Lincomycin industrially produced by Streptomyces lincolnensis can be adopted to treat infections caused by Gram-positive bacteria. SLCG_Lrp, a transcriptional regulator of the Lrp family, was first identified to positively regulate lincomycin biosynthesis. However, the regulatory role of SLCG_Lrp is yet to be elucidated. This study utilized RNA-seq for comparing the transcriptome profile of original-strain LCGL and the ΔSLCGL_Lrp mutant. A total of 244 genes comprising 116 downregulated and 128 upregulated genes were differentially expressed between LCGL and ΔSLCGL_Lrp. An in-depth analysis revealed that SLCG_Lrp promotes nitrate assimilation but inhibits fatty acid metabolism, as well as directly regulates five regulators participating in the modulation of multiple cellular processes. With individual inactivation of those regulatory genes in S. lincolnensis LCGL, we confirmed the FadR transcriptional regulator SLCG_2185 was obviously correlated with lincomycin production and found it to transcriptionally stimulate the lincomycin biosynthetic cluster. Furthermore, SLCG_2185 overexpression in the high-yield S. lincolnensis LA219X promoted lincomycin production by 17.8%, and SLCG_2185 being co-overexpressed with SLCG_Lrp in LA219X increased lincomycin production by 28.1% compared to LA219X. Therefore, this investigation not only provides a direction for further investigations regarding the regulation mechanism of SLCG_Lrp, but also provides a basis for guiding the further improvement of lincomycin levels. Full article
(This article belongs to the Special Issue Antibiotic Production in Streptomyces)
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16 pages, 365 KiB  
Review
Probiotics as Potential Therapy in the Management of Non-Alcoholic Fatty Liver Disease (NAFLD)
by Margalida Monserrat-Mesquida, Cristina Bouzas, Catalina M. Mascaró, Silvia Tejada and Antoni Sureda
Fermentation 2023, 9(4), 395; https://doi.org/10.3390/fermentation9040395 - 19 Apr 2023
Cited by 1 | Viewed by 2432
Abstract
Background: Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease, the prevalence of which has increased over the years. The management of this pathology is not clear, and a specific pharmacological drug that can treat NAFLD is not available. In this [...] Read more.
Background: Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease, the prevalence of which has increased over the years. The management of this pathology is not clear, and a specific pharmacological drug that can treat NAFLD is not available. In this sense, efforts are focused on the potential use of compounds with a natural origin that can contribute to reversing hepatic steatosis. Supplementation with probiotics, live microorganisms, is a potential strategy for the management of NAFLD. Methods: In the present review, the available information on the potential therapeutic effects of probiotics in NAFLD, mainly in animal models and in some clinical trials, is summarized. Results: Studies carried out using animal models of NAFLD induced by a high-fat diet have shown the beneficial effects of probiotic supplementation in reducing liver steatosis and normalizing the blood lipid profile and liver enzyme activities. In addition, a decrease in lipogenesis and an increase in lipolysis have been observed, together with a reduction in the pro-oxidative and pro-inflammatory state and a normalization of intestinal dysbiosis. Clinical trials have reported a decrease in the serum transaminases and an improved lipid profile, as well as a reduction in inflammatory markers. Conclusions: In conclusion, probiotic supplementation can be used as a potential therapy for the management of NAFLD. Full article
(This article belongs to the Special Issue The Role of Antioxidant Compounds in Fermented Foods)
18 pages, 2329 KiB  
Article
Modelling of Catechin Extraction from Red Grape Solids under Conditions That Simulate Red Wine Fermentation
by Judith Unterkofler, David W. Jeffery, Patrick C. Setford, Jean Macintyre and Richard A. Muhlack
Fermentation 2023, 9(4), 394; https://doi.org/10.3390/fermentation9040394 - 19 Apr 2023
Viewed by 1784
Abstract
Digital control systems are well established in many industries and could find application in the wine sector. Of critical importance to red wine quality, the efficient and targeted extraction of polyphenols from red grape solids during alcoholic fermentation could be a focus for [...] Read more.
Digital control systems are well established in many industries and could find application in the wine sector. Of critical importance to red wine quality, the efficient and targeted extraction of polyphenols from red grape solids during alcoholic fermentation could be a focus for automation. Smart technologies such as model predictive control (MPC) or fuzzy logic appear ideal for application in a complex process such as wine polyphenol extraction, but require mathematical models that accurately describe the system. The aim of this study was to derive and validate a model describing the extraction of catechin (a representative polyphenol) from red grape solids under simulated fermentation conditions. The impact of ethanol, fermentable sugar, and temperature on extraction rate was determined, with factor conditions chosen to emulate those present in industry practice. A first-order approach was used to generate an extraction model based on mass conservation that incorporated temperature and sugar dependency. Coefficients of determination (R2) for all test scenarios exceeded 0.94, indicating a good fit to the experimental data. Sensitivity analysis for the extraction rate and internal cross-validation showed the model to be robust, with a small standard error in cross-validation (SECV) of 0.11 and a high residual predictive deviation (RPD) of 17.68. The model that was developed is well suited to digital technologies where low computational overheads are desirable, and industrial application scenarios are presented for future implementation of the work. Full article
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9 pages, 2321 KiB  
Communication
Very High Thermotolerance of an Adaptive Evolved Saccharomyces cerevisiae in Cellulosic Ethanol Fermentation
by Bin Zhang, Mesfin Geberekidan, Zhao Yan, Xia Yi and Jie Bao
Fermentation 2023, 9(4), 393; https://doi.org/10.3390/fermentation9040393 - 19 Apr 2023
Cited by 2 | Viewed by 1398
Abstract
High thermotolerance is an important property of Saccharomyces cerevisiae for stable and efficient bioethanol production, especially for large-scale bioethanol production with weak heat transfer and the simultaneous saccharification and fermentation (SSF) of lignocellulosic biomass at high temperatures (above 40 °C). Despite extensive studies [...] Read more.
High thermotolerance is an important property of Saccharomyces cerevisiae for stable and efficient bioethanol production, especially for large-scale bioethanol production with weak heat transfer and the simultaneous saccharification and fermentation (SSF) of lignocellulosic biomass at high temperatures (above 40 °C). Despite extensive studies involving metabolic engineering and chemical mutagenesis, the improvement of thermotolerance in S. cerevisiae under harsh thermal stress (42–45 °C) has been limited. A highly thermotolerant strain, S. cerevisiae Z100, by a 91 days’ laboratory adaptive evolution in wheat straw hydrolysate was applied for cellulosic ethanol fermentation. The results showed that the cell survival ratio of S. cerevisiae Z100 at 50 °C improved by 1.2 times that of the parental strain. The improved thermotolerance of S. cerevisiae Z100 at 50 °C was found to contribute significantly to enhanced cellulosic ethanol fermentability. The ethanol production of S. cerevisiae Z100 increased by 35%, 127%, and 64% when using wheat straw as feedstock after being maintained at 50 °C for 12 h, 24 h, and 48 h, respectively. Transcriptome analyses suggested that the enhanced trehalose and glycogen synthesis, as well as carbon metabolism, potentially contributed to the improved thermotolerance and the ethanol fermentability of S. cerevisiae Z100. This study provides evidence that adaptive evolution is an effective method for increasing the thermotolerance of the S. cerevisiae strain for stable and efficient cellulosic ethanol production. Full article
(This article belongs to the Section Industrial Fermentation)
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12 pages, 1996 KiB  
Article
Impact of Rumen Fluid Storage on In Vitro Feed Fermentation Characteristics
by Bereket Zeleke Tunkala, Kristy DiGiacomo, Pablo S. Alvarez Hess, Frank R. Dunshea and Brian J. Leury
Fermentation 2023, 9(4), 392; https://doi.org/10.3390/fermentation9040392 - 19 Apr 2023
Cited by 4 | Viewed by 1723
Abstract
Storing rumen fluid (RF) has the potential to standardize subsequent in vitro feed fermentation studies. The first phase of this experiment aimed to evaluate the effect of two RF storage methods on gas composition and dry matter disappearance (DMD) in wheat grain and [...] Read more.
Storing rumen fluid (RF) has the potential to standardize subsequent in vitro feed fermentation studies. The first phase of this experiment aimed to evaluate the effect of two RF storage methods on gas composition and dry matter disappearance (DMD) in wheat grain and lucerne hay under in vitro fermentation. The storage methods were as follows: (1) snap-freezing RF using liquid nitrogen and then storing it at −80 °C (−80 °C); and (2) mixing RF with 5% dimethyl sulfoxide (DMSO), subsequently freezing it at −20 °C (D−20 °C), and comparing it to fresh RF on days 1, 14, and 30 post collection. The objective of the second phase was to quantify the impact of preserving the RF for 180 days at D−20 °C on the in vitro fermentation parameters. The methane composition was lower (p < 0.001) in both the preserved RFs than in the fresh RF. There was no difference (p < 0.05) in DMD values between days 14 and 30. The average cumulative gas production and DMD from the RF stored at D−20 °C was higher than that from the RF stored at −80 °C. Moreover, there was no difference between day 30 and day 180 in the total gas production and lag time when fermenting with RF preserved at D−20 °C. Therefore, storing RF at D−20 °C is preferable to storing it at −80 °C when access to fresh RF is limited. Full article
(This article belongs to the Special Issue In Vitro Fermentation, 2nd Edition)
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14 pages, 1686 KiB  
Article
Supplementing Yogurt with Probiotic Bifidobacteria to Counter Chronic Kidney Disease
by Gerrit A. Stuivenberg, John A. Chmiel, Polycronis P. Akouris, Jessica White, Hannah Wilcox, Shannon Seney, Jeremy P. Burton and Gregor Reid
Fermentation 2023, 9(4), 391; https://doi.org/10.3390/fermentation9040391 - 18 Apr 2023
Cited by 3 | Viewed by 2979
Abstract
Chronic kidney disease (CKD) disproportionately affects populations in developing countries. In sub-Saharan Africa, CKD prevalence is high (12–23%) and is associated with cardiovascular manifestations. Uremic toxins, especially p-cresol and p-cresyl sulfate, are associated with the disease. Reducing uremic toxins in the [...] Read more.
Chronic kidney disease (CKD) disproportionately affects populations in developing countries. In sub-Saharan Africa, CKD prevalence is high (12–23%) and is associated with cardiovascular manifestations. Uremic toxins, especially p-cresol and p-cresyl sulfate, are associated with the disease. Reducing uremic toxins in the body slows disease progression and improves patient outcomes. Probiotic Bifidobacterium breve HRVD521-US, B. animalis HRVD524-US, B. longum SD-BB536-JP, and B. longum SD-CECT7347-SP internalize p-cresol and improve longevity in vivo. In 2002, Tanzanian communities were taught to produce probiotic yogurt (Fiti®) supplemented with Lacticaseibacillus rhamnosus GR-1. This has expanded to over 100 community producers across the country. To produce yogurt that could reduce the burden of CKD by sequestering uremic toxins, we decided to test the addition of p-cresol-clearing bifidobacterial strains. By repeating the Fiti® production process performed in Tanzanian communities and adding a bifidobacterial strain, we found that they were successfully incorporated into the yogurt without any detrimental effect on sensory properties or viable counts. Three of the four strains significantly reduced p-cresol when added to a simulated colonic environment. In conclusion, this study has shown that Fiti® sachets provided to Tanzanian communities to produce yogurt can be supplemented with strains that can potentially confer additional health benefits. Full article
(This article belongs to the Special Issue Fermented Foods for Boosting Health)
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10 pages, 733 KiB  
Article
Investigation of a Broad-Bean Based Low-Cost Medium Formulation for Bacillus subtilis MSCL 897 Spore Production
by Oskars Grigs, Elina Didrihsone and Emils Bolmanis
Fermentation 2023, 9(4), 390; https://doi.org/10.3390/fermentation9040390 - 17 Apr 2023
Cited by 2 | Viewed by 1400
Abstract
Bacillus subtilis (Bs) is a bacterium that benefits plants and is used in the production of bio-fungicides. The cultivation of Bs is a crucial step in bio-control preparation production, as it greatly impacts the quality and price of the final product. In a [...] Read more.
Bacillus subtilis (Bs) is a bacterium that benefits plants and is used in the production of bio-fungicides. The cultivation of Bs is a crucial step in bio-control preparation production, as it greatly impacts the quality and price of the final product. In a series of shake flask experiments, we investigated the economically feasible broth composition for spore production of Bacillus subtilis MSCL 897, a Latvian soil isolate. Our study investigated the impact of utilizing legume-based flours (such as broad bean, grey pea, and soybean) as the primary nitrogen source, along with sugar-beet molasses, sucrose, or glucose as the carbon source, and yeast extract, peptone, and corn-steep liquor as growth factor additives. Additionally, we examined the effect of using (NH4)2HPO4 or urea as supplementary nitrogen sources, as well as previously established media formulations, on spore yield. Our results showed that a culture medium composed of broad bean flour (10 g/L) and molasses (10 g/L) led to spore productivity of 1.35 ± 0.47 × 108 CFU/mL at 48 h. By enriching the culture medium base constituents with a minor (0.5–1.0 g/L) yeast extract or corn-steep liquor additive, a notable increase in spore productivity was observed, with values of 2.00 ± 0.28 × 108 and 2.34 ± 0.18 × 108 CFU/mL at 48 h, respectively, and sporulation efficiency > 80–90%. As a result, we achieved a high spore yield of the Bacillus subtilis MSCL 897 strain, demonstrating the competitiveness of our approach, which relied on a low-cost medium made mainly from locally available and renewable raw materials. Full article
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15 pages, 1798 KiB  
Review
Current Status, Challenges, and Prospects for the Biological Production of Vanillin
by Wankui Jiang, Xiaoyue Chen, Yifan Feng, Jingxiang Sun, Yujia Jiang, Wenming Zhang, Fengxue Xin and Min Jiang
Fermentation 2023, 9(4), 389; https://doi.org/10.3390/fermentation9040389 - 17 Apr 2023
Cited by 7 | Viewed by 4855
Abstract
Vanillin has been widely used as a flavoring agent in the food industry and as a precursor in the medicine and polymer industries. However, the use of chemically synthesized vanillin is prohibited in food and some other industries. Additionally, the harsh conditions and [...] Read more.
Vanillin has been widely used as a flavoring agent in the food industry and as a precursor in the medicine and polymer industries. However, the use of chemically synthesized vanillin is prohibited in food and some other industries. Additionally, the harsh conditions and toxic substrates in chemically synthesized vanillin lead to some environmental challenges and energy waste. With the rapid development of synthetic biology, the biological production of vanillin from renewable resources through microbial fermentation has gained great attention owing to its high selectivity and environmentally friendly properties. Accordingly, this article will discuss the vanillin biosynthesis technology from the aspects of chassis cell types and substrate types. The key enzymes involved in metabolic pathways are also discussed. Then, we summarize some improvements in the process of vanillin production to increase its production and reduce the toxicity of vanillin in microorganisms, and the possible future directions for vanillin biosynthesis will also be outlined. Full article
(This article belongs to the Special Issue Application of Microbial Fermentation in Organic Matter Production)
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13 pages, 297 KiB  
Review
Therapeutic and Dietary Support for Gastrointestinal Tract Using Kefir as a Nutraceutical Beverage: Dairy-Milk-Based or Plant-Sourced Kefir Probiotic Products for Vegan and Lactose-Intolerant Populations
by Divakar Dahiya and Poonam Singh Nigam
Fermentation 2023, 9(4), 388; https://doi.org/10.3390/fermentation9040388 - 17 Apr 2023
Cited by 8 | Viewed by 5192
Abstract
Kefir is a fermented milk beverage different in consistency and taste from other popular milk-product yogurt. Unlike yogurt prepared using lactic acid bacteria in fermentation, milk is fermented for kefir production using preculture in the form of kefir grains. Therefore, the metabolic activities [...] Read more.
Kefir is a fermented milk beverage different in consistency and taste from other popular milk-product yogurt. Unlike yogurt prepared using lactic acid bacteria in fermentation, milk is fermented for kefir production using preculture in the form of kefir grains. Therefore, the metabolic activities of a mixed culture, including strains of bacteria and yeast, contribute to the probiotic characteristics in kefir. This article is based on the review of published studies on the functionality and nutraceutical properties of kefir. The therapeutic and dietary properties of kefir beverage and its probiotic strains have been discussed for their several health benefits. Concise selected information mostly from recent reports has been presented for two categories of kefir products: milk used for the production of dairy-based traditional kefir beverages for the lactose-tolerant population, and the plant-sourced substrates used for the production of dairy-free kefir beverages for lactose-intolerant and vegan consumers. Full article
14 pages, 1060 KiB  
Article
Metagenomic Binning Revealed Microbial Shifts in Anaerobic Degradation of Phenol with Hydrochar and Pyrochar
by Tao Luo, Jun He, Zhijian Shi, Yan Shi, Shicheng Zhang, Yan Liu and Gang Luo
Fermentation 2023, 9(4), 387; https://doi.org/10.3390/fermentation9040387 - 17 Apr 2023
Cited by 3 | Viewed by 1515
Abstract
Phenolic compounds, which are difficultly degraded, are one of the main toxic threats faced in the anaerobic digestion (AD) process. It has previously been reported that hydrochar/pyrochar produced by the hydrothermal liquefaction/pyrolysis of biomass can enhance AD by promoting direct interspecific electron transfer [...] Read more.
Phenolic compounds, which are difficultly degraded, are one of the main toxic threats faced in the anaerobic digestion (AD) process. It has previously been reported that hydrochar/pyrochar produced by the hydrothermal liquefaction/pyrolysis of biomass can enhance AD by promoting direct interspecific electron transfer (DIET). The present study investigated the effects of different hydrochars and pyrochars on the anaerobic degradation of phenol and provided deep insights into the related micro-organisms at the species level through genome-centric metagenomic analysis. Compared with the control experiment, the addition of hydrochar and pyrochar shortened the lag time. However, hydrochar created a large increase in the maximum methane production rate (Rm) (79.1%) compared to the control experiments, while the addition of pyrochar decreased Rm. Metagenomic analysis showed that the addition of carbon materials affected the relative abundance of genes in the phenol anaerobic degradation pathway, as well as the species and relative abundance of phenol degrading micro-organisms. The relative abundance of key genes for phenol degradation, such as bsdB, bamB, oah, etc., under the action of hydrochar was higher than those under the action of pyrochar. In addition, hydrochar-enriched phenol degradation-related bacteria (Syntrophus aciditrophicus, etc.) and methanogen (Methanothrix soehngenii, etc.). These micro-organisms might improve the phenol degradation efficiency by promoting DIET. Therefore, hydrochar had a more significant effect in promoting anaerobic degradation of phenol. Full article
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21 pages, 2370 KiB  
Review
A Review on Catalytic Depolymerization of Lignin towards High-Value Chemicals: Solvent and Catalyst
by Yannan Wang, Lianghuan Wei, Qidong Hou, Zhixin Mo, Xujun Liu and Weizun Li
Fermentation 2023, 9(4), 386; https://doi.org/10.3390/fermentation9040386 - 17 Apr 2023
Cited by 10 | Viewed by 2886
Abstract
Lignin is a type of natural aromatic material with potential application prospects obtained from lignocellulosic biomass. Recently, the valorization of lignin has received increasing attention from both industry and academia. However, there is still a challenge in the efficient valorization of lignin due [...] Read more.
Lignin is a type of natural aromatic material with potential application prospects obtained from lignocellulosic biomass. Recently, the valorization of lignin has received increasing attention from both industry and academia. However, there is still a challenge in the efficient valorization of lignin due to the complexity and stability of the lignin structure. Recent work has been focused on the catalytic depolymerization of lignin to explore a promising and efficient way to valorize lignin into chemicals with high value and biofuels. Considerable research has focused on catalysts, solvents, and reaction parameters during the lignin depolymerization process, which significantly affects product distribution and productivity. Thus, in a catalytic depolymerization process, both catalysts and solvents have a significant influence on the depolymerization effect. This review article assesses the current status of the catalytic hydrogenolysis of lignin, mainly focusing on the solvents and catalysts during the reaction. First, various solvents applied in the lignin depolymerization reactions are extensively overviewed. Second, the recent progress of metal catalysts as well as their supports is summarized. Furthermore, a discussion of the challenges and prospects in this area is included. Full article
(This article belongs to the Special Issue Lignin Valorization: Recent Trends and Future Perspective)
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20 pages, 4116 KiB  
Review
Microbial and Commercial Enzymes Applied in the Beverage Production Process
by Fernanda Cosme, António Inês and Alice Vilela
Fermentation 2023, 9(4), 385; https://doi.org/10.3390/fermentation9040385 - 17 Apr 2023
Cited by 5 | Viewed by 5191
Abstract
Enzymes are highly effective biocatalysts used in various industrial processes, playing a key role in winemaking and in other fermented beverages. Many of the enzymes used in fermentation processes have their origin in fruits, in the indigenous microbiota of the fruit, and in [...] Read more.
Enzymes are highly effective biocatalysts used in various industrial processes, playing a key role in winemaking and in other fermented beverages. Many of the enzymes used in fermentation processes have their origin in fruits, in the indigenous microbiota of the fruit, and in the microorganisms present during beverage processing. Besides naturally occurring enzymes, commercial preparations that usually blend different activities are used (glucosidases, glucanases, pectinases, and proteases, among others). Over the years, remarkable progress has been made in enhancing enzyme performance under operating conditions. The winemaking industry has observed a significant improvement in production levels, stimulating the introduction of technological innovations that aim to enhance efficiency and wine quality. Enzymes have traditionally been used in the beverage industry; however, others have been introduced more recently, with numerous studies aimed at optimizing their performance under processing conditions, including the use of immobilized enzymes. Therefore, one major goal of the current review is to give a detailed overview of the endogenous enzyme potential of wine microorganisms, as well as of enzymes obtained from grapes or even commercial preparations, studied and already in use in the beverage industry, and to present the future trends in enzyme production and application. Full article
(This article belongs to the Special Issue Fermentation: Screening, Enzyme Induction and Production)
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17 pages, 4707 KiB  
Article
Non-Conventional Sucrose-Based Substrates: Development of Non-Dairy Kefir Beverages with Probiotic Potential
by Pedro Paulo Lordelo Guimarães Tavares, Clariane Teixeira Pessoa Mamona, Renata Quartieri Nascimento, Emanuele Araújo dos Anjos, Carolina Oliveira de Souza, Rogéria Comastri de Castro Almeida, Maria Eugênia de Oliveira Mamede and Karina Teixeira Magalhães-Guedes
Fermentation 2023, 9(4), 384; https://doi.org/10.3390/fermentation9040384 - 17 Apr 2023
Cited by 4 | Viewed by 2522
Abstract
There is a scarcity of studies evaluating the influence of different commonly marketed sugars in water kefir beverage production. Therefore, this study aimed to evaluate the fermentation of water kefir grains in different sugary solutions: brown, demerara, refined, coconut, and cane molasses. A [...] Read more.
There is a scarcity of studies evaluating the influence of different commonly marketed sugars in water kefir beverage production. Therefore, this study aimed to evaluate the fermentation of water kefir grains in different sugary solutions: brown, demerara, refined, coconut, and cane molasses. A total of 10% of each type of sugar was dissolved in sterile water to which 10% of kefir grains were then added and fermented for 48 h at room temperature. Analyses of pH/acidity, soluble solids, lactic/acetic acids, and lactic acid bacteria and yeast counts were performed, in addition to grain weighing at 0 h, 24 h, and 48 h. The microbial biodiversity was measured using PCR-DGGE and DNA sequencing at the species level. A sensory acceptance test was performed on all beverages. Lactobacillus, Lacticaseibacillus, Lentilactobacillus Lactococcus, Leuconostoc, Acetobacter, Saccharomyces, Kluyveromyces, Lachancea, and Kazachstania were present in the kefir grains and the beverages. Molasses showed a more intense fermentation, with greater production of organic acids and higher lactic/acetic acid bacteria and yeast counts (7.46 and 7.49 log CFU/mL, respectively). Refined sugar fermentation had a lower microbial yield of lactic/acetic acid bacteria (6.87 log CFU/mL). Smith’s salience index indicates that the brown-sugar kefir beverage was better accepted among the tasters. The results indicate that the use of alternative sources of sugar to produce water kefir beverages is satisfactory. This opens up new perspectives for the application of kefir microorganisms in the development of beverages with probiotic and functional properties. Full article
(This article belongs to the Section Probiotic Strains and Fermentation)
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23 pages, 4018 KiB  
Article
Screening and Identification of the Strain Pediococcus acidilactici and Its Application in Fermentation of Corn–Soybean Meal Uncooked Materials
by Su Xu, Xinyu Song, Jirong Liu, Wenjuan Zhang, Xiaochen Yu, Dianyu Yu and Jianjun Cheng
Fermentation 2023, 9(4), 383; https://doi.org/10.3390/fermentation9040383 - 17 Apr 2023
Cited by 1 | Viewed by 2044
Abstract
Cost and contamination are the bottleneck problems for the replacement of antibiotics with fermented feed. A strain of lactic acid bacteria was isolated and screened from acidified apple juice and identified as Pediococcus acidilactici using morphological, physiological, and biochemical tests and 16S rDNA [...] Read more.
Cost and contamination are the bottleneck problems for the replacement of antibiotics with fermented feed. A strain of lactic acid bacteria was isolated and screened from acidified apple juice and identified as Pediococcus acidilactici using morphological, physiological, and biochemical tests and 16S rDNA sequence analysis. The strain was combined with Bacillus subtilis and Saccharomyces cerevisiae to ferment raw corn–soybean meal, and the two-stage fermentation process was optimized with a single-factor test, orthogonal test, and response surface methodology. Compared with unfermented raw material, the protein content of fermented feed was increased by 5.21 percentage points (p < 0.05) and the total amino acids were increased by 3.7 percentage points (p < 0.05), making it rich in amino acids essential for pigs. The high-throughput sequencing results showed that, at the species level, the highest relative abundances of bacteria in the fermentation system were those of Pediococcus acidilactici and Bacillus subtilis, and the most abundant fungi was Saccharomyces cerevisiae. No pathogenic bacteria, such as Salmonella, were detected in the fermentation system. This paper provides a feasible scheme for cheap preparation of an alternative to antibiotics, fermented feed, with uncooked raw materials. It has positive significance for promoting high-value utilization of agricultural and sideline products and improving feed cost-effectiveness. Full article
(This article belongs to the Special Issue Feed Fermentation: A Technology Using Microorganisms and Additives)
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12 pages, 4916 KiB  
Article
Coordinated Expression of the Genes Encoding FocA and Pyruvate Formate-Lyase Is Important for Maintenance of Formate Homeostasis during Fermentative Growth of Escherichia coli
by Michelle Kammel and Robert Gary Sawers
Fermentation 2023, 9(4), 382; https://doi.org/10.3390/fermentation9040382 - 16 Apr 2023
Cited by 2 | Viewed by 1317
Abstract
FocA is a pentameric membrane channel that translocates formic acid bidirectionally across the cytoplasmic membrane of Escherichia coli during fermentation. The focA gene is co-transcribed with pflB, which encodes pyruvate formate-lyase, the enzyme that generates formate. Recent evidence has suggested that FocA [...] Read more.
FocA is a pentameric membrane channel that translocates formic acid bidirectionally across the cytoplasmic membrane of Escherichia coli during fermentation. The focA gene is co-transcribed with pflB, which encodes pyruvate formate-lyase, the enzyme that generates formate. Recent evidence has suggested that FocA serves to regulate intracellular formate levels and thus helps to maintain pH balance in fermenting cells. In this study, we aimed to provide support for this hypothesis by either altering FocA levels, mutating the chromosomal focA gene, or introducing additional copies of focA, either alone or with pflB, on a plasmid and monitoring the effect on intracellular and extracellular formate levels. Our results revealed that the expression of the native focA-pflB operon ensures that intracellular formate levels remain relatively constant during exponential phase growth, even when additional, mutated copies of focA that encode FocA variants are introduced in trans. Enhancing focA expression was balanced by higher formate excretion from the cell. Using chromosomal focA gene variants confirmed that FocA, and not PflB, sets intracellular formate homeostatic levels. Moreover, any chromosomal focA mutation that altered the formate concentration inside the cell caused a negative fermentative growth phenotype. Thus, FocA governs intracellular formate levels to ensure optimal growth during glucose fermentation. Full article
(This article belongs to the Section Microbial Metabolism, Physiology & Genetics)
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14 pages, 1365 KiB  
Article
Statistical Medium Optimization for the Production of Anti-Methicillin-Resistant Staphylococcus aureus Metabolites from a Coal-Mining-Soil-Derived Streptomyces rochei CMB47
by Ibtissem Djinni, Warda Djoudi, Chahinaz Boumezoued, Halima Barchiche, Samiha Souagui, Mouloud Kecha and Ines Mancini
Fermentation 2023, 9(4), 381; https://doi.org/10.3390/fermentation9040381 - 15 Apr 2023
Cited by 3 | Viewed by 1959
Abstract
The development of novel antibacterial drugs needs urgent action due to the global emergence of antibiotic resistance. In this challenge, actinobacterial strains from arid ecosystems are proving to be promising sources of new bioactive metabolites. The identified Streptomyces rochei strain CMB47, isolated from [...] Read more.
The development of novel antibacterial drugs needs urgent action due to the global emergence of antibiotic resistance. In this challenge, actinobacterial strains from arid ecosystems are proving to be promising sources of new bioactive metabolites. The identified Streptomyces rochei strain CMB47, isolated from coal mine Saharan soil, provided an ethyl acetate extract which tested against a series of pathogens. It displayed a minimum inhibitory concentration of <0.439 µg/mL against MRSA. A statistical experimental design using a response surface methodology (RSM) based on the second-order rotatable central composite design (RCCD) was planned to develop an efficient fermentation process able to improve the bioactive metabolite production. The optimal conditions were determined for starch and NaNO3 concentrations, incubation time and the initial pH value, reaching the inhibition zone diameter of 20 mm, close to the experimental value, after validation of the model. A bioassay-guided fractionation of the crude extract provided the most active fractions, which were analyzed by HPLC equipped with a photodiode array detector and coupled online with an electrospray mass spectrometer (HPLC-DAD/ESI-MS), obtaining preliminary indications on the molecular structures of the metabolites. These results support the potential interest in further investigations into the purification and full characterization of the metabolites responsible for the biological activity observed so far. Full article
(This article belongs to the Special Issue Pharmaceutical Fermentation: Antibiotic Production and Processing)
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26 pages, 2352 KiB  
Article
Bioinformatic Modeling (In Silico) of Obtaining Bioactive Peptides from the Protein Matrix of Various Types of Milk Whey
by Aleksandr G. Kruchinin, Ekaterina I. Bolshakova and Irina A. Barkovskaya
Fermentation 2023, 9(4), 380; https://doi.org/10.3390/fermentation9040380 - 14 Apr 2023
Viewed by 1979
Abstract
Whey is a by-product of the production of various types of cottage cheese and cheese, casein, and coprecipitates. Conditions of milk coagulation directly affect the physico-chemical properties of whey and the formation of its protein profile. This fact makes it difficult to standardize [...] Read more.
Whey is a by-product of the production of various types of cottage cheese and cheese, casein, and coprecipitates. Conditions of milk coagulation directly affect the physico-chemical properties of whey and the formation of its protein profile. This fact makes it difficult to standardize the protein profile of milk whey for its further processing. Whey proteins have a great potential to release a wide range of bioactive peptides (BAP), capable of reducing the risk of a number of chronic food-related diseases. Computer modeling of an enzymatic hydrolysis of proteins is one of the ways to increase the efficiency of BAP release studies and to reduce the number of labor consuming experiments. This research is aimed at generating a digital model of the peptide complex of different whey types with predicted bioactivity, safety, and sensory properties using bioinformatic modeling approaches. The study was performed with the use of the proteomic databases tools according to the algorithm of hybrid strategy of bioinformatic modeling developed earlier. As a result of the study, taking into account the ranking of the proteins ratio in the protein profile, the hydrolysis by the protease complex chymotrypsin C-subtilisin was characterized as the maximum efficacy method to release peptides with both antioxidant and ACE-inhibitory activity. It was also observed that the bioactive peptides obtained as a result of in silico hydrolysis after GI digestion simulation can be considered safe in terms of allergic reactions and toxicological effects. Full article
(This article belongs to the Section Fermentation for Food and Beverages)
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11 pages, 1773 KiB  
Article
Effects of Four Critical Gene Deletions in Saccharomyces cerevisiae on Fusel Alcohols during Red Wine Fermentation
by Tongshuai Yan, Zexiang Wang, Haoyang Zhou, Jiaojiao He and Shishui Zhou
Fermentation 2023, 9(4), 379; https://doi.org/10.3390/fermentation9040379 - 14 Apr 2023
Cited by 1 | Viewed by 2035
Abstract
Excessive fusel alcohols in red wine will bring an uncomfortable bitterness and generate an intoxicating effect, which affects the quality and attractivity of the red wine. In order to achieve better regulation of fusel alcohols in red wine, strains with LEU1 and PDC5 [...] Read more.
Excessive fusel alcohols in red wine will bring an uncomfortable bitterness and generate an intoxicating effect, which affects the quality and attractivity of the red wine. In order to achieve better regulation of fusel alcohols in red wine, strains with LEU1 and PDC5 deletions were constructed, and seven engineered yeast strains based on THI3 and BAT2 deletions were applied to red wine fermentation to dissect the effects of four critical genes on fusel alcohols during wine fermentation. The fermentation results of these recombinant strains showed that the deletion of THI3 increased the contents of n-propanol, isobutanol, and isoamyl alcohol by 48.46%, 42.01%, and 7.84%, respectively; the deletion of BAT2 decreased isoamyl alcohol and isobutanol by 32.81% and 44.91%; the deletion of PDC5 and LEU1 decreased isoamyl alcohol by 40.21% and 68.28%, while increased isobutanol by 24.31% and 142%, respectively; the deletion of THI3 exerted a negative influence on the reduction of isoamyl alcohol caused by BAT2 or PDC5 deletion; the deletion of THI3 and PDC5 had a synergistic effect on the increase of isobutanol, while BAT2 and PDC5 deletion presented no additive property to the decrease of isoamyl alcohol. Hence, it is concluded that either BAT2, PDC5, or LEU1 deletion can effectively decrease fusel alcohols, especially isoamyl alcohol, which provides an important reference for the control of fusel alcohols in red wine. Full article
(This article belongs to the Special Issue Advances in Beverages, Food, Yeast and Brewing Research 2.0)
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17 pages, 3758 KiB  
Article
PEP4-Allele Modification Provides an Industrial Brewing Yeast with Malate Stress Tolerance
by Hongbo Zhang, Wanting Hu, Yuhang Lu, Chi Shen, Hongfei Yao, Xiaomei Yang, Xiaomin Yao, Tianyi Lu and Baowei Hu
Fermentation 2023, 9(4), 378; https://doi.org/10.3390/fermentation9040378 - 14 Apr 2023
Cited by 1 | Viewed by 1396
Abstract
Acid stress is a challenging condition that yeast cells must overcome during fermentation. Enhancing the inherent tolerance of industrial Saccharomyces cerevisiae to organic acid stresses is crucial for increasing fermentation efficiency and reducing economic costs. In a previous study, we constructed a Saccharomyces [...] Read more.
Acid stress is a challenging condition that yeast cells must overcome during fermentation. Enhancing the inherent tolerance of industrial Saccharomyces cerevisiae to organic acid stresses is crucial for increasing fermentation efficiency and reducing economic costs. In a previous study, we constructed a Saccharomyces cerevisiae strain SWY85S with improved tolerance to citric acid stress by modifying the second PEP4-allele. Malic acid is a dominant organic acid in grapefruit, which forms the acidic constituents of wine fermentation mash and finished products. We investigated the malic acid stress tolerance of the strain SWY85S in comparison with that of a strain with one PEP4-allele disrupted and the wild-type strain in this study. Our results revealed that the strain SWY85S demonstrated greater tolerance of malic acid stress, regardless of whether it was cultured with adequate nutrient supplies or under amino acid starvation. Moreover, the strain SWY85S performed remarkably in converting glucose to ethanol during fermentation under malic acid stress. This study provides insights into the role of a vacuolar PEP4-allele coding product in response to environmental stress and the physiological mechanism of yeast to withstand organic acid stress. Full article
(This article belongs to the Section Microbial Metabolism, Physiology & Genetics)
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14 pages, 3152 KiB  
Article
Changes in Physicochemical Properties, Metabolites and Antioxidant Activity of Edible Grass during Spontaneous Fermentation
by Xianxiu Li, Tao He, Yangchen Mao, Jianwei Mao, Xiaojin Lai, Hangjia Tu, Yi Zhou and Ruyi Sha
Fermentation 2023, 9(4), 377; https://doi.org/10.3390/fermentation9040377 - 14 Apr 2023
Cited by 3 | Viewed by 1736
Abstract
Fermentation is a crucial technology to improve the nutritional and functional properties of food materials. In this study, edible grass was processed by spontaneous fermentation. Changes in physicochemical properties, metabolites, and antioxidant activity of edible grass were investigated by colorimetric method and chromatography [...] Read more.
Fermentation is a crucial technology to improve the nutritional and functional properties of food materials. In this study, edible grass was processed by spontaneous fermentation. Changes in physicochemical properties, metabolites, and antioxidant activity of edible grass were investigated by colorimetric method and chromatography mass spectrometry-based non-targeted metabolomics approach during fermentation. The highest total polyphenol and total flavonoid contents, and free radical scavenging abilities were observed on the 17th day of fermentation. The maximum activity of superoxide dismutase was maintained stable in the fermentation time range of 7–70 days. In total, 16 differential metabolites were identified with fermentation duration up to 124 days. Fermented edible grass exerted protection from H2O2-induced cytotoxicity on HepG2 cells, regulating by the reduction in reactive oxygen species level and the increase in antioxidant enzyme activities. Overall, this study confirms that fermented edible grass obtained by spontaneous fermentation presented favorable nutritional and functional quality, and is expected to be a kind of food with antioxidant function. Full article
(This article belongs to the Special Issue Nutrition and Health of Fermented Foods, 2nd Edition)
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19 pages, 2678 KiB  
Article
Selection of Saccharomyces cerevisiae Isolates from Helan Mountain in China for Wine Production
by Lanlan Hu, Xueao Ji, Jiacong Li, Yangyang Jia, Xiaohong Wang and Xiuyan Zhang
Fermentation 2023, 9(4), 376; https://doi.org/10.3390/fermentation9040376 - 14 Apr 2023
Cited by 1 | Viewed by 1536
Abstract
S. cerevisiae strains were isolated and identified from vineyards and the spontaneous fermentation must at the eastern foot of Helan Mountain in China, and their oenological properties and fermentation abilities were analyzed. From the total of 199 S. cerevisiae strains isolated and identified, [...] Read more.
S. cerevisiae strains were isolated and identified from vineyards and the spontaneous fermentation must at the eastern foot of Helan Mountain in China, and their oenological properties and fermentation abilities were analyzed. From the total of 199 S. cerevisiae strains isolated and identified, 14 isolates (F4-13, F5-7, F5-9, F5-12, F5-18, F5-19, F5-21, F6-8, F6-23, F9-23, SXY-4, HT-10, ZXY-17, MXY-19) exhibited excellent tolerance to sugar, SO2, and ethanol. Among the isolates, the strain F4-13 exhibited the better oenological properties, with low H2S production (+), suitable flocculation ability (58.74%), and reducing-L-malic acid ability (49.07%), and generated high contents of polyphenol, anthocyanin, tannin, terpenes, and higher alcohols, which contributed to the improvement of the red fruity and floral traits of the wines. The obtained results provide a strategy for the selection of indigenous S. cerevisiae for wine fermentation to produce high-quality wine with regional characteristics. Full article
(This article belongs to the Section Fermentation for Food and Beverages)
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25 pages, 8837 KiB  
Article
Study on Scale-Up of Anaerobic Fermentation Mixing with Different Solid Content
by Zhe Li, Hancheng Lu, Zixuan Zhang and Baoqing Liu
Fermentation 2023, 9(4), 375; https://doi.org/10.3390/fermentation9040375 - 14 Apr 2023
Cited by 1 | Viewed by 2636
Abstract
The scale-up technology of anaerobic fermentation stirring equipment is worthy of attention. Computational fluid dynamics (CFD) simulations were used to study the scale-up of anaerobic fermentation mixing under different solid content conditions. The applicability of different scale-up criteria was analyzed by investigating the [...] Read more.
The scale-up technology of anaerobic fermentation stirring equipment is worthy of attention. Computational fluid dynamics (CFD) simulations were used to study the scale-up of anaerobic fermentation mixing under different solid content conditions. The applicability of different scale-up criteria was analyzed by investigating the relative parameters, such as the blade tip speed and the Reynolds number. On this basis, the scale-up index was optimized and verified. The results revealed the applicability of five common scale-up criteria under different solid content conditions. When the solid content is less than 5%, the anaerobic fermentation tank should be scaled up according to the same Weber number. When the solid content is between 5% and 10%, the anaerobic fermentation tank should be scaled up according to the same blade tip speed; it was especially suitable for anaerobic fermentation and other conditions that limit the shear rate. Scaling up according to the Reynolds number was not recommended due to the poor mixing effect. When the scale-up index x reached 0.75, there was no need to further reduce it. For anaerobic fermentation systems, the suitable scale-up indices selected for 5%, 10%, and 15% solid content were 1.1, 1, and 0.75, respectively. Full article
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