Fermentation, Volume 10, Issue 6 (June 2024) – 50 articles

This review discusses the recent advancements in cost-effective fermentation methods for producing bacterial nanocellulose (BC) from food and agro-industrial waste. Achieving economical cell culture media is crucial for large-scale BC production, requiring nutrient-rich media at low cost to maximize cellulose yield. Various pretreatment methods, including chemical, physical, and biological approaches, are stated to break down waste into accessible molecules for cellulose-producing bacteria. Additionally, strategies such as dynamic bioreactors and genetic engineering methods are investigated to enhance BC production. This review also focuses on the environmental impact assessment and updated application challenges of BC such as medical applications, energy storage/electronics, filtration membranes, and food packaging. By providing insights from the recent literature findings, this review highlights the innovative potential and challenges in economically and efficiently producing BC from waste streams. Full article

The global food production system faces several challenges, including significant environmental impacts due to traditional agricultural practices. The rising demands of consumers for food products that are safe, healthy, and have animal welfare standards have led to an increased interest in alternative proteins and the development of the cellular agriculture field. Within this innovative field, precision fermentation has emerged as a promising technological solution to produce proteins with reduced ecological footprints. This review provides a summary of the environmental impacts related to the current global food production, and explores how precision fermentation can contribute to address these issues. Additionally, we report on the main animal-derived proteins produced by precision fermentation, with a particular focus on those used in the food and nutraceutical industries. The general principles of precision fermentation will be explained, including strain and bioprocess optimization. Examples of efficient recombinant protein production by bacteria and yeasts, such as milk proteins, egg-white proteins, structural and flavoring proteins, will also be addressed, along with case examples of companies producing these recombinant proteins at a commercial scale. Through these examples, we explore how precision fermentation supports sustainable food production and holds the potential for significant innovations in the sector. Full article

This study investigated the effect of molasses addition on the fermentation quality, chemical composition, and bacterial community of seed pumpkin peel residue (SPPR) mixed with sunflower straw (SS) in microstorage feed. Molasses additions on a dry matter basis (DM) were divided into three groups: 0% control (CON), 1% (MA), and 2% (MB), and the raw materials underwent mixed microstorage for a period of 60 days. MA exhibited the highest content of dry matter (DM), the lowest content of neutral detergent fiber (NDF), acid detergent fiber (ADF), and ammoniacal nitrogen (NH₃-N), as well as the lowest microbial diversity abundance and the highest relative abundance of lactobacilli (p < 0.05). MB demonstrated the highest crude protein (CP) content and acetic acid (AA) and propionic acid (PA) concentrations, with the lowest pH. In conclusion, the addition of molasses could enhance the quality of mixed microsilage feeds composed of seeded pumpkin peel pomace (SPPR) and sunflower straw (SS), with the optimal addition of molasses being 1% on a DM basis. Full article

Light controls the developmental, physiological, morphological, and metabolic responses of many fungi. Most fungi respond primarily to blue, red, and green light through their respective photoreceptors. In this study, a screening of different light wavelengths’ effects on submerged Pleurotus ostreatus cultivation in baffled flasks was conducted. P. ostreatus growth was not inhibited in all tested conditions, while an equal or higher protein content was observed in comparison with dark conditions. Red and green light favored exopolysaccharide (EPS) production while red and blue light favored intracellular polysaccharide (IPS) production. To focus on EPS production, the effect of red and green light wavelengths on the production of the polysaccharide via submerged cultivation of P. ostreatus LGAM 1123 was tested. Submerged cultivation using red light in baffled flasks resulted in EPS production of 4.1 ± 0.4 g/L and IPS content of 23.1 ± 1.4% of dry weight (dw), while green light resulted in EPS production of 4.1 ± 0.2 g/L and 44.8 ± 5.2% dw IPS content. Similar production levels were achieved in a 3.5 L bioreactor using red light. The EPS produced using red light revealed a polysaccharide with a higher antioxidant activity compared to the polysaccharides produced by green light. In addition, the analysis of the crude polysaccharides has shown differences in biochemical composition. The structural differences and β glucan’s existence in the crude polysaccharides were confirmed by FT-IR analysis. Overall, these polysaccharides could be used in the food industry as they can enhance the functional health-promoting, physicochemical, and sensory properties of food products. Full article

In wine technology, the on-line measurement of redox potential is a fast, accurate, and reliable measurement that provides insight into the metabolism of Saccharomyces cerevisiae, its microbial activity, and the oxidation and reduction state of wine, as well as insight into its quality and stability. The significance of the redox potential measurement and control in wine technology as well as the maintenance and regulation of fermentation redox potential using temperature and carbon dioxide fluxes are discussed. Redox potential levels from Eh 100 to 180 mV are typical for non-oxidized wine that is bottling-ready, while levels of Eh 270 to 460 mV represent oxidized wines with typical failures. The relevance of redox potential measurement during the 2-year maturation of Blau Fränkisch wine in 225 L oak barrels at six levels at a temperature 15 °C is presented. The measurement of the redox potential, expressing heterogeneity in redox layers during wine maturation in oak barrels, is represented in various oxido-reductive fermentation zones. On the contrary, the end of the maturation process is indicated by the homogeneity of redox zones, where the matured wine shows no differences in redox measurement on all levels. Using redox potential as a key scale-up criteria ensures comparable and reproducible amounts of the final product even in geometrically non-similar fermenter systems. Full article

Acetohydroxyacid synthase (AHAS) is a key enzyme in the first step of the branched-chain amino acid synthesis pathway, and the production of acetohydroxybutyrate from one molecule of 2-ketobutyric acid and one molecule of pyruvate. AHAS is inhibited by feedback from L-valine, L-leucine, and L-isoleucine, and the expression of ilvBN, the gene encoding AHAS, is regulated by all three branched-chain amino acids. A change in amino acids 20–22 on the regulatory subunit (M13 mutation) removes the feedback inhibition by valine. We cloned the gene encoding AHAS (ilvBN) into a vector and then transfected it into Escherichia coli BL21 for expression with targeted changes in amino acids 20–22 on the regulatory subunit, and then determined the activity of the mutated AHAS and its inhibitory effects on valine, isoleucine, and leucine. The enzyme containing the M13 mutation was feedback resistant to all three amino acids. Previous studies have suggested that the binding sites for the three branched-chain amino acids may be at the same variable center. We investigated the enzymatic properties of wild-type and mutant AHAS, modeled their crystal structures, and resolved the mechanism of feedback inhibition induced by mutant M13, which will be useful for continuing the modification of AHAS and the design of broad-spectrum herbicides. Full article

Huangshui is a typical organic wastewater in Chinese Baijiu production, with high pollution and valuable ingredients. Conventional wastewater treatment leads to resource-wasting and environmental pollution. It is urgent that the demand for effective Huangshui treatment with the development of the Baijiu-making industry. This review systematically summarizes recent studies, revealing the main characteristics and application of Huangshui, focusing on the application of the rich microbial resources and flavor substances, which provides a practical approach to cascade and full use of Huangshui in medicine, cosmetic, functional food, fertilizer, and wastewater treatment fields. Further research suggested that Huangshui can also be used as an external carbon source for the denitrification system or as an organic liquid water-soluble fertilizer for more fruits and grains. The applications favor improving production efficiency and lowering pollutant emissions and introduce novel concepts for the sustainable development of related industries. Thus, Chinese Baijiu plants can achieve the near-zero emissions of wastewater and cleaner production. Full article

This study aims to investigate the probiotic properties of various isolated strains of Lactiplantibacillus plantarum. Specifically, the focus is on examining the expression of the glutamic acid decarboxylase (GAD) gene and its role in the production of gamma-aminobutyric acid (GABA), a promising postbiotic metabolite. The investigation includes comprehensive analyses of morphology, genetics, resilience against bile, NaCl, and simulated pancreatin juice (SPJ), carbohydrate fermentation patterns, antibacterial activity, susceptibility to antibiotics, and the presence of β-D-galactosidase and GAD enzymes. Six L. plantarum strains exhibited remarkable resilience against bile, NaCl, and SPJ, as well as susceptibility to antibiotics and antagonistic behavior against pathogens. These strains also showed the presence of β-D-galactosidase. Additionally, five L. plantarum strains were found to harbor the gad gene. Further biochemical analysis of four specific L. plantarum strains revealed promising profiles consisting of antibiotics, vitamins, hormones, and a diverse array of metabolites with potential immunotherapeutic properties. This study highlights the substantial potential of Lactiplantibacillus plantarum in generating beneficial postbiotic metabolites. The identified strains offer exciting avenues for further exploration, with potential applications in functional foods and pharmaceuticals. This research opens up possibilities for harnessing the probiotic and postbiotic potential of L. plantarum to develop novel products with health-promoting properties. Full article

This study aimed to explore the fermentative performance of nine lactic acid bacterial strains with probiotic potential during sorghum fermentation. The strain’s attributes including proliferation counts, pH levels, production of organic acid antibacterial activity, and their ability to break down starch were evaluated during the fermentation period in the presence and absence of glucose as a carbon source. In addition, the inhibitory activity of these potential probiotic strains against pathogenic bacteria (Salmonella typhimurium, Escherichia coli, and Staphylococcus aureus) was examined through a co-culturing technique. The results demonstrated that all 4 Lactobacillus strains exhibited robust growth in both glucose and glucose-free fermentation experiments. Glucose supplementation significantly enhanced lactic acid yield which ranged from 0.19 to 0.44% compared to fermentation without glucose which ranged from 0.04 to 0.29%. The selected Lactobacillus strains effectively lowered the media pH below 4.0 after 24 h, producing substantial lactic acid. Notably, in the absence of glucose, only Lb. helveticus D7 and Lb. amylolyticus D12 achieved pH levels below 4 after 8 h, producing the highest lactic acid amounts of 0.27 and 0.29% after 24 h, respectively. Amylase activity was detected on two strains, D7 and D12. Furthermore, most of the tested Lactobacillus strains demonstrated complete inhibition (6 log to 0 Log CFU/mL) of pathogen growth after 24 h of co-culturing, suggesting their potential for enhancing the safety quality of sorghum-based fermented products. Full article

This study aimed to investigate the effects of yeast cultures on the antioxidant capacity, rumen fermentation, and growth performance of goats in the summer. An in vitro experiment was conducted using yeast culture supplemented at 0% (control), 0.6% (test 1), 0.9% (test 2), and 1.2% (test 3) of the dry matter (DM) weight of the basal diet. With a 24 h fermentation, the pH value; the total short-chain fatty acid, acetic acid, propionic acid, and butyric acid concentrations; and the degradability of the DM, the neutral detergent fiber, and the acid detergent fiber were significantly increased (p < 0.05) in tests 2 and 3 compared with the control group. In the feeding experiment, thirty-six crossbreed goats aged 3.0 ± 0.5 months with a body weight of 11.08 ± 1.41 kg were divided, and the yeast culture was supplemented at 0% (control), 0.90% (test 1), and 1.20% (test 2) of the basal diet. Similar effects on rumen fermentation parameters were obtained in test 1 and 2 groups compared to the in vitro experiment. Moreover, the dry matter intake, average daily gain, serum total antioxidant capacity, and the activities of total superoxide dismutase and glutathione peroxidase were significantly higher and the malondialdehyde concentration was significantly lower (p < 0.05) in tests 1 and 2 compared with the control. The results indicated that yeast culture (0.90%) could improve the antioxidant capacity, rumen fermentation, and growth performance of goats in summer. The optimal supplementation concentration is 0.90% DM. Full article

Converting corn grains into bioethanol is an expanding practice for sustainable fuel production, but this is accompanied by the production of large quantities of by-products such as whole stillage. In the present study, the influence of advanced wet oxidation and steam explosion (AWOEx) pretreatment on biogas production and lignocellulose decomposition of corn whole stillage (CWS) was evaluated using semi-continuous thermophilic reactors. The digestion of the CWS was shown to be feasible with an organic loading rate (OLR) of 1.12 ± 0.03 kg VS/m³ day and a hydraulic retention time (HRT) of 30 days, achieving a methane yield of 0.75 ± 0.05 L CH₄/g VS_fed for untreated stillage and 0.86 ± 0.04 L CH₄/g VS_fed for pretreated stillage, corresponding with an increase in methane yield of about 15%. However, the reactors showed unstable performance with the highest investigated OLRs and shortest HRTs. Under optimal conditions, the conversion efficiencies of COD, cellulose, hemicellulose, and lignin were 88, 95, 97, and 59% for pretreated CWS, and 86, 94, 95, and 51% for untreated CWS, respectively. Microbial community analysis showed that Proteiniphilum, MBA03, and Acetomicrobium were the dominant genera in the digestate and were likely responsible for the conversion of proteins and volatile fatty acids in CWS. Full article

Biorefineries (BRFs) that process the organic fraction of municipal solid waste and generate bioproducts and bioenergies have attracted attention because they can simultaneously address energy and environmental problems/needs. The objective of this article was to critically review the microbial production of hyaluronic acid (MPHA) and its production profile for its integration into a GBAER-type BRF (a type of BRF based on organic wastes) and to identify the environmental and economic sustainability aspects of the modified BRF that would confirm it as a sustainable option. It was found that the MPHA by selected strains of pathogenic Streptococci was moderate to high, although the trend to work with genetically transformed (GT) (innocuous) bacteria is gaining momentum. For instance, A GT strain of Corynebacterium glutamicum reached a maximum HA production of 71.4 g L⁻¹. MPHA reports that use organic wastes as sources of carbon (C) and nitrogen (N) are scarce. When alternative sources of C and N were used simultaneously, HA production by S. zooepidemicus was lower than that with conventional sources. We identified several knowledge gaps that must be addressed regarding aspects of process scale-up, HA industrial production, economic feasibility and sustainability, and environmental sustainability of the MPHA. Full article

Naturally colored fermented foods currently represent the trend toward a global demand for healthier products. This work produced naturally blue and green ice creams using C-phycocyanin (C-PC) and spirulina residual biomass (RB). The ice creams were assessed based on microbiological analysis, color stability over 6 months, antioxidant activity before and after in vitro digestion, and sensory evaluation. Considering the microorganisms that must be analyzed in accordance with Brazilian legislation, no growth was detected during the storage period. L*, a*, and b* were maintained according to the expected colors. The blue color was intoned over the shelf life (SC-PC *b −9.46 to −19.44 and MC-PC *b from −9.87 to −18.04). The antioxidant activity of the fermented ice creams SC-PC and SRB increased from 15.4 to 41.3 and from 15.3 to 38.0 µM TE/g, respectively, after bioaccessibility analysis. The C-PC ice cream’s appearance received the highest rating, with 70.26% of volunteers expressing a strong preference, highlighting its attractiveness. However, there were no significant differences compared to control samples in the global acceptance. The RB ice cream presented lower results for flavor but moderate acceptance. Thus, these fermented ice creams presented color stability over 6 months, and their antioxidant activity increased after in vitro digestion, highlighting their biological potential. Full article

As a result of climate change, the phenology of grapes has been altered, mainly by increasing the sugar content and decreasing the acidity of ripe grapes. This shift, when the must is fermented, affects the quality of the wine. In this regard, the use of selected Saccharomyces and non-Saccharomyces yeasts to mitigate these undesirable effects in wine fermentations entails new strategies to improve their control and also to obtain wines better adapted to current consumer preferences. This work focuses on the use of a commercially available strain of Lachancea thermotolerans immobilized in biological support to form “microbial biocapsules”, comparing its effect with a free format and spontaneous fermentation on alcoholic fermentation and volatile compound composition. These biocapsules, consisting of yeast cells attached to fungal pellets, are being tested to improve wine sensory attributes and also to facilitate yeast inoculation in fermentative and clarification winemaking processes, as well as to reduce time and production costs. The composition of young wines obtained with L. thermotolerans, inoculated as free or biocapsule formats, were compared with those obtained by the traditional method of spontaneous fermentation using native yeast by quantifying 12 oenological variables and the contents in 12 major volatiles, 3 polyols, and 46 minor volatile compounds. The analytical data matrix underwent statistical analysis to compare and establish significant differences at p ≤ 0.05 level between the different wines obtained. Among the major volatiles and polyols, only ethyl acetate, 1,1-diethoxyethane, methanol, 2-methyl-1-butanol, acetoin, ethyl lactate, and glycerol showed significant differences in L. thermotolerans wines. Also, from the minor volatile metabolites, eight showed a significant dependence on the format used for L. thermotolerans, and the other nine volatiles were dependent on both yeast and inoculation format. Only 27 volatiles were selected as aroma-active compounds with odor activity values higher than 0.2 units. Statistical analysis showed a clear separation of the obtained wines into groups when subjected to Principal Component Analysis, and the fingerprinting of wines made with biocapsules shows intermediate values between the two remaining inoculation formats, particularly in the fruity/ripe fruit, green, and floral series. The organoleptic evaluation of wines results in significantly higher values in taste, overall quality, and total score for wines obtained with biocapsules. Full article

In classical methods of wine production, amino acids play a critical role, as they are fundamental to all types of fermentation. Beyond their consumption in fermentative processes, amino acids undergo several transformations, such as decarboxylation, which produces biogenic amines. These biogenic amines can increase under certain conditions, such as the presence of spoilage bacteria or during malolactic fermentation. Alternative methods of vinification were applied, using sulfur dioxide as a preservative (+SO₂) and methods without added sulfites. Alternative methods of vinification were applied using sulfur dioxide as a preservative (+SO₂) and methods without added sulfite (−SO₂). Monitoring was conducted for Cabernet Sauvignon red (CS), Cabernet Sauvignon rosé (CSR), Fetească regală still (FR), and Fetească regală frizzante (FRF). Alternative procedures employed the use of Pichia kluyveri for its ability to block the oxidation reactions of grapes, malolactic fermentation for all wines without sulfur dioxide (−SO₂) to ensure superior stability, and the use of several tannin mixtures to avoid oxidation reactions. Correlations were considered between the amino acids and biogenic amines that have a direct relation through decarboxylation or deamination. The pH of the wines, total acidity, and volatile acidity as principal factors of microbiological wine evolution remained constant. The highest mean concentrations of the detected biogenic amines were putrescine at 23.71 ± 4.82 mg/L (CSRSO₂), tyramine at 14.62 ± 1.50 mg/L (FR-SO₂), cadaverine at 4.36 ± 1.19 mg/L (CS-SO₂), histamine at 2.66 ± 2.19 mg/L (FR + SO₂), and spermidine at 9.78 ± 7.19 mg/L (FR + SO₂). The wine conditions ensured the inhibition of decarboxylases, but some correlations were found with the corresponding amino acids such as glutamine (r = −0.885, p < 0.05) (CSR-SO₂), tyrosine (r = −0,858, p < 0.05) (FR-SO₂), lysine (r = −0.906, p < 0.05) (FR-SO₂), and histamine (r = −0.987, p < 0.05) (CSR-SO₂). Multivariate analysis was performed, and no statistical differences were found between samples with (+SO₂) and without added sulfur dioxide (−SO₂). The vinification conditions ensured the wines’ stability and preservation and the conditions of producing biogenic amines at the lowest levels in order to not interfere with the olfactive and gustative characteristics. Full article

Anaerobic digestion (AD) is a widely applied technology for renewable energy generation using biogas as energy vector. The existing microbial consortium in this technology allows for the use of several types of biomass as substrates. A promising alternative for the production of high-value products (e.g., mixed volatile fatty acids–VFAs, hydrogen) is the use of modified AD. There are several techniques to achieve this objective by modifying the operating conditions of the process. The literature has described the best AD routes for generating renewable energy or high-value products based on specific substrate types and operating conditions. Few studies have reported the integral fraction valorization of the AD process applying the biorefinery concept. This article provides an analysis of the different routes that favor the production of energy carriers and high-value products involving key issues related to operating conditions and substrates. Moreover, AD is addressed through the biorefinery concept. Finally, a case study is presented where renewable energy and mixed VFAs are generated by applying the biorefinery concept in a number of proposed scenarios using organic kitchen food waste (OKFW) as feedstock. The case study involves an experimental and simulation stage. Then, the economic feasibility of the proposed scenarios is evaluated. In conclusion, AD is a promising and economically feasible technology to produce valuable products from several types of waste materials. Full article

A variety of mathematical models have been developed to simulate the biochemical and physico-chemical aspects of the anaerobic digestion (AD) process to treat organic wastes and generate biogas. However, all these models, including the most widely accepted and implemented Anaerobic Digestion Model No.1, remain incapable of adequately representing the material balance of AD and are therefore inherently incapable of material conservation. The absence of robust mass conservation constrains reliable estimates of any kinetic parameters being estimated by regression of empirical data. To address this issue, the present work involved the development of a “framework” for a mass-conserving atomistic mathematical model which is capable of mass conservation, with a relative error in the range of machine precision value and an atom balance with a relative error of ±0.02% whilst obeying the Henry’s law and electroneutrality principle. Implementing the model in an Excel spreadsheet, the study calibrated the model using the empirical data derived from batch studies. Although the model shows high fidelity as assessed via inspection, considering several constraints including the drawbacks of the model and implementation platform, the study also provides a non-exhaustive list of limitations and further scope for development. Full article

Lactic acid bacteria (LAB), due to their many advantageous features, have been utilized in food manufacturing for centuries. Spontaneous fermentation, in which LAB play a fundamental role, is one of the oldest methods of food preservation. LAB survival and viability in various food products are of great importance. During technological processes, external physicochemical stressors appear often in combinations. To ensure the survival of LAB, adjustment of optimal physicochemical conditions should be considered. LAB strains should be carefully selected for particular food matrices and the technological processes involved. The LAB’s robustness to different environmental stressors includes different defense mechanisms against stress, including the phenomenon of adaptation, and cross-protection. Recently established positive health effects and influence on human wellbeing have caused LAB to be some of the most desirable microorganisms in the food industry. A good understanding of LAB defense and adaptation mechanisms can lead to both optimization of food production and storage conditions, as well as to obtaining LAB strains with increased tolerance to stressors. Hopefully, as a result, the final food product with naturally present or added LAB can achieve outstanding quality and safety with health benefits that meet consumer expectations. Full article

Solventogenic Clostridium species are important for establishing the sustainable industrial bioproduction of fuels and important chemicals such as acetone and butanol. The inherent versatility of these species in substrate utilization and the range of solvents produced during acetone butanol–ethanol (ABE) fermentation make solventogenic Clostridium an attractive choice for biotechnological applications such as the production of fuels and chemicals. The functional qualities of these microbes have thus been identified to be related to complex regulatory networks that play essential roles in modulating the metabolism of this group of bacteria. Yet, solventogenic Clostridium species still struggle to consistently achieve butanol concentrations exceeding 20 g/L in batch fermentation, primarily due to the toxic effects of butanol on the culture. Genomes of solventogenic Clostridium species have a relatively greater prevalence of genes that are intricately controlled by various regulatory molecules than most other species. Consequently, the use of genetic or metabolic engineering strategies that do not consider the underlying regulatory mechanisms will not be effective. Several regulatory factors involved in substrate uptake/utilization, sporulation, solvent production, and stress responses (Carbon Catabolite Protein A, Spo0A, AbrB, Rex, CsrA) have been identified and characterized. In this review, the focus is on newly identified regulatory factors in solventogenic Clostridium species, the interaction of these factors with previously identified molecules, and potential implications for substrate utilization, solvent production, and resistance/tolerance to lignocellulose-derived microbial inhibitory compounds. Taken together, this review is anticipated to highlight the challenges impeding the re-industrialization of ABE fermentation, and inspire researchers to generate innovative strategies for overcoming these obstacles. Full article

Here, a comprehensive investigation was conducted under various operational strategies aimed at enhancing biohydrogen production via dark fermentation, with a specific focus on the lactate metabolic pathway, using powdered cheese whey as a substrate. Initially, a batch configuration was tested to determine both the maximum hydrogen yield (100.2 ± 4.2 NmL H₂/g COD_fed) and the substrate (total carbohydrates) consumption efficiency (94.4 ± 0.8%). Subsequently, a transition to continuous operation was made by testing five different operational phases: control (I), incorporation of an inert support medium for biomass fixation (II), addition of carbon-coated, zero-valent iron nanoparticles (CC-nZVI NPs) at 100 mg/L (III), and supplementation of Fe₂O₃ nanoparticles at concentrations of 100 mg/L (IV) and 300 mg/L (V). The results emphasized the critical role of the support medium in stabilizing the continuous system. On the other hand, a remarkable increase of 10% in hydrogen productivity was observed with the addition of Fe₂O₃ NPs (300 mg/L). The analysis of the organic acids’ composition unveiled a positive correlation between high butyrate concentrations and improved volumetric hydrogen production rates (25 L H₂/L-d). Moreover, the presence of iron-based NPs effectively regulated the lactate concentration, maintaining it at low levels. Further exploration of the bacterial community dynamics revealed a mutually beneficial interaction between lactic acid bacteria (LAB) and hydrogen-producing bacteria (HPB) throughout the experimental process, with Prevotella, Clostridium, and Lactobacillus emerging as the predominant genera. In conclusion, this study highlighted the promising potential of nanoparticle addition as a tool for boosting biohydrogen productivity via lactate-driven dark fermentation. Full article

(1) Objectives: Traditional kombucha (K) is a fermented beverage obtained from black or green tea infusion. Besides traditional substrates, the possibility of using alternative ingredients resulted in changes in metabolic profile and biological activity. The aim of this work was to study an alternative kombucha (KJ) prepared by the addition of jujube powder to black tea. (2) Materials and Methods: Changes in pH, protein, sugars, phenolic (TPC), flavonoid (TFC), and vitamin C and B12 content were evaluated at different time points over a period of 45 days. The identification of polyphenols by HPLC DAD and the antioxidant capacity by DPPH, ABTS, and FRAP tests of all samples was also carried out. (3) Results: The results showed higher protein, total phenolic content, and antioxidant capacity in KJ samples than in K ones. Vitamin C content increased during fermentation and reached its maximum concentration on day 45 (7.1 ± 0.3 mg/100 mL) for KJ. Caffeine in the supplemented samples was the main biocompound among those identified. Vitamin B12 formed on day 4 in K and after 24 h in KJ samples, remaining constant at the initial value of 2.30 ± 0.01 mg/100 mL up to day 45. (4) Conclusions: The results highlight that the fortification of kombucha with jujubes improved its biological activity and the content of bioactive compounds. Full article

Investigating the intricate pathways through which FH06 fermentation broth exerts lipid-lowering and weight-loss effects is pivotal for advancing our comprehension of metabolic regulation and therapeutic interventions. Ultrahigh-performance liquid chromatography quadrupole electrostatic field orbit trap mass spectrometry (UHPLC-QE-MS) detection and the ChEMBL database were used to determine the effective compounds in the FH06 fermentation broth and predict their targets. The TTD database and DisGeNET database were used to query obesity-related targets. The STRING database was used to construct protein interaction information. The Gene Ontology (GO) database and the Kyoto Encyclopedia of Genes and Genomes (KEGG) database were used to perform biological function annotation (GO) and KEGG pathway enrichment analyses of the targets. Results: A total of 85 effective compounds were screened from the fermentation broth of FH06; these compounds may act on TP53, PPARG, TNF, and other targets through 10 signaling pathways, such as the chemical carcinogenesis-receptor activation and lipid and atherosclerosis pathways, and exert pharmacological effects, such as hypoglycemic effects and weight loss. They also have anti-inflammatory, antioxidant, antitumor, and immunoregulatory effects. These findings reveal the active ingredients of FH06 fermentation broth and its multi-target and multi-channel characteristics in lipid lowering and weight loss. This study has positive implications for the clinical treatment of obesity using FH06, providing a theoretical and scientific basis for further developing of FH06-assisted lipid-lowering products. Full article

In addition to energy recovery, the anaerobic digestion of agro-industrial byproducts can also produce different high-value-added compounds. Two-stage and single-stage reactors were compared for microbial communities’ selection and long-chain fatty acid (LCFA) accumulation to investigate which microbial genera are most linked to the production of these compounds. The microbial communities present in the two reactors’ configuration in the steady state were characterised by 16S rRNA amplicon sequencing, while LCFAs were extracted and quantified from digestate samples by gas chromatography. The results showed the differentiation of the microbially dominant families in the two setups: Defluviitaleaceae and Clostridiaceae in the acidogenic and methanogenic reactor of the two-stage reaction respectively, while Dysgonomonadaceae in the single-stage set-up. LCFA accumulation was significantly detected only in the acidogenic reactor, with palmitic (2764 mg/kg), linoleic (1795 mg/kg) and stearic (1751 mg/kg) acids as the most abundant. The dominance of Defluviitaleaceae UCG 011, along with the low abundance of the LCFA oxidiser Syntrophomonas spp. in the acidogenic reactor, could be linked to the accumulation of such compounds. Therefore, the different microbial communities shaped by the two reactors’ configuration affected the accumulation of LCFAs, indicating that the two-stage anaerobic digestion of agro-industrial byproducts was more effective than single-stage digestion. Full article

Irradiation with ultraviolet A (UVA) plays an important role in the pathogenesis of skin photoaging since it increases oxidative stress and inflammation in the epidermis. There is an urgent need to screen, investigate, and apply the potential anti-photoaging active ingredients. Agaricus blazei Murill (ABM) polysaccharides have a wide range of promising pharmacological applications. Previous studies have confirmed their antioxidant effect, but whether it has an anti-photoaging effect is unclear. In this study, two ABM polysaccharides (AB-J and AB-K) were obtained to discuss the potential photodamage-protective capacity. The free radical scavenging abilities in vitro, the safety assessment, and their protective effects and mechanisms on UVA-induced human fibroblasts (HSFs) were evaluated. The intracellular antioxidant enzyme levels and extracellular matrix proteins, such as COL-I and ELN, were significantly accelerated, and metalloproteinases (MMP-1, and MMP-9) were decreased by AB-J and AB-K. The Keap-1-Nrf2/ARE signaling pathway was activated, thus inducing the upregulated expression of downstream genes (Ho-1 and Nqo-1). The suppression of P38 and Jnk1 by AB-J and AB-K was speculated to be the inducer of the activation of the Keap-1-Nrf2/ARE signaling pathway. Owing to the excellent exhibition of AB-J, its safety assessment and the structural characterization are discussed further. Full article

Recently, there has been worldwide growth in consumer nutrition awareness, which has resulted in a market-driven increase in the demand for “functional food”, which, in addition to traditional nutrients, also contains ingredients with specific properties that have a beneficial effect on human health. One of the types of functional food is so-called “probiotic food”, which includes, for example, frozen desserts. These products appear attractive to the consumer because of their sensory, nutritional and refreshing qualities. Due to progress in science, genetics, the acquisition of new sources of probiotic microorganisms and new plant varieties, the beneficial effects of the characteristic metabolites of the microbiome—so-called postbiotics—and also aspects of NGPs (Next Generation Probiotics), work is under way to optimize the technology used during the production of such products. At the same time, there is an observed market-based increase in the supply of new formulations based only on plant-origin materials with different technological modifications, including prebiotic enrichment, which allows for the production of a synbiotic product. Therefore, the objective of this study is a narrative review, in combination with the authors’ own experiments, concerning the impact of various factors on functional, plant-origin frozen desserts, from the point of view of maintaining their quality. Full article

2-phenylethanol (2-PE) is a valuable aromatic alcohol with diverse applications in cosmetics, food, beverages, and pharmaceutical industries. Currently, 2-PE is produced either through chemical synthesis or by extraction from plant materials. However, both conventional production methods have their own limitations. Therefore, there is a need for more eco-friendly and cost-effective approaches to produce natural 2-PE. Biotechnological routes, particularly microbial fermentations, hold promise for natural 2-PE production, especially when using low-cost substrates. In this study, 2-PE was produced by de novo synthesis via the shikimate pathway, using the yeast Yarrowia lipolytica in a medium composed of sugar beet molasses (SBM) and yeast extract (YE) as carbon and nitrogen sources, respectively. A genetically engineered strain was generated, in which the SUC2 gene was transformed, expressing the invertase enzyme, enabling Y. lipolytica to efficiently utilize SBM as a cost-effective substrate. A central composite design allowed for the optimization of the concentrations of the carbon and nitrogen sources, resulting in approximately 0.71 g_(2-PE)/L_{(culture medium)}. The results obtained highlight the potential of utilizing SBM as a low-cost substrate for 2-PE production, advancing biotechnological approaches in fragrance synthesis. Full article

Extra energy consumption, inefficient nitrogen removal, and excessive sludge production are major challenges faced by wastewater treatment plants (WWTPs) that rely on the traditional activated sludge process. Fermentation of wasted activated sludge (WAS) and novel nitrogen removal technologies based on partial nitrification (PN) have emerged as promising solutions to these issues. Recent studies have revealed an innovative strategy that integrates these two processes by supplementing fermentation liquid into activated sludge to induce PN. This review summarizes the research progress on PN establishment induced by the fermentation process. The microbiology and establishment methods of PN are briefly introduced, followed by a detailed discussion on the process, influencing factors, and product characteristics of WAS fermentation. The core section focuses on the side-stream and main-stream approaches of fermentation-induced PN, comparing their performance and application prospects. The potential mechanisms are explored, with an emphasis on the roles of free ammonia for the side-stream approach and the high tolerance of ammonium oxidizers to in-site fermentation stress for the main-stream approach. Finally, the limitations of the current research and future perspectives are discussed, highlighting the need for further investigation into microbial ecology, process optimization, and long-term stability. This review aims to provide insights into the synergistic integration of WAS fermentation and PN for sustainable and energy-efficient wastewater treatment. Full article

The Cornus kousa tree, which is of Asian origin, is often cultivated for ornamental purposes and used in traditional medicine. The tree produces sugar-rich fruits, which are potential habitats for natural yeasts. The identification of new yeast strains has many advantages for the industry and research. This study aimed to isolate and identify yeast species from C. kousa fruits and to understand their microbial ecology. Ripe and rotten fruits, which had fallen on the ground naturally, were collected and soaked in culture media, followed by plate spreading for colony growth. The morphological examination revealed three distinct colony types, including two from the ripe fruits and one from the rotten fruits. The analysis of the internal transcribed spacer 1 region indicated three yeast strains corresponding to the three colony types: Torulaspora delbrueckii and Pichia kluyveri from the ripe fruits and Saccharomyces cerevisiae from the rotten fruits. The metabolic characterizations demonstrated that all three yeasts efficiently consumed glucose and produced alcohol. S. cerevisiae exhibited the strongest fermentation ability and the highest growth rate. These findings showed that Cornus kousa fruit is a source of diverse yeast species, with distinct species associated with different states of fruit decomposition. Full article

Because olive pomace (the main by-product of olive oil production) is phytotoxic, new applications must be investigated to minimize its negative environmental impact. In this work, olive pomace was fermented for 4 and 32 days at room temperature, having in view its valorization as a novel food, thereby creating opportunities for the food industry and addressing a challenge of the olive oil sector. The chemical and microbiological modifications that occurred along the fermentation were followed. The results showed no significant differences (p > 0.05) in total protein between the control and the fermented samples; however, the latter exhibited higher levels of essential amino acids. The major nonessential and essential amino acids were glutamic acid and leucine in all samples. There was a significant increase in the total fat of the 32-day sample and the main fatty acid was oleic acid in all samples. There were considerable reductions in total vitamin E, phenolics, and antioxidant activity values post-fermentation. Hydroxytyrosol replaced oleacein as the main phenolic in the 32-day sample. A sharp increase in total microorganisms occurred (2.20 × 10² to 3.00 × 10⁴–2.01 × 10⁷ colony forming units/mL) but no pathogenic microorganisms were detected. Overall, olive pomace fermentation creates novel products for the food industry with a balanced nutritional composition. Full article