Search Results (102)

Environmental and economic concerns due to the increasing use of fossil-based chemicals, especially fuel, may be alleviated by production of renewable fuels based on plant biomass, in particular, waste. Multistep cascades of enzymatic reactions are being increasingly sought to enhance the effectiveness of sustainable, environment-friendly processes. The biochemical transformation of lignocellulosic biomass and oils into fatty acid esters (“biodiesel”) involves biomass pretreatment, followed by polysaccharide hydrolysis and sugar fermentation to alcohol, either sequentially or simultaneously. Subsequent trans-esterification with waste or non-food-based oils is usually carried out in an organic solvent. Biocatalysis in aqueous emulsion offers significant advantages. This study presents a novel “one-pot” emulsion-based process for transforming unmodified cellulose and castor oil into biodiesel via hybridized yeasts with cellulose-coated micro-particles incorporating cellulolytic enzymes and lipases. The resultant consolidated bioprocess of saccharification, fermentation, and transesterification (cSFT) promotes effective substrate channeling and can potentially serve as a model for emulsion-based “one-pot” transformations of cellulose into valuable chemicals. Full article

Dark fermentation of food waste for biohydrogen production can simultaneously achieve waste resource utilization and clean energy production. However, the widespread application of this technology remains constrained by challenges such as low substrate hydrolysis efficiency and suboptimal metabolic performance of functional microorganisms. This study evaluated the synergistic enhancement of biohydrogen production from food waste through dark fermentation by integrating thermal–alkaline (TA) pretreatment with varying concentrations (50, 100, 150, and 200 mg/L) of nickel–cobalt oxide nanoparticles (NiCo₂O₄ NPs), and the underlying mechanisms involved were systematically elucidated. The results demonstrated that individual TA pretreatment (pH 11, 70 °C, 1 h) and TA coupled with NiCo₂O₄ NPs (100 mg/L) significantly (p < 0.01) enhanced the cumulative biohydrogen yields of the food waste dark fermentation by 20.89% and 35.76%, respectively. Mechanism research revealed that TA pretreatment effectively facilitated the dissolution and hydrolysis of macro-molecular organics such as polysaccharides and proteins, thereby enhancing the bio-accessibility of fermentation substrates. The introduction of NiCo₂O₄ NPs further intensified the microbial biohydrogen-producing metabolism by augmenting enzymatic activity and enriching functional bacteria. NiCo₂O₄ NPs significantly (p < 0.001) enhanced the overall activity of hydrogenase by 95.10% compared to the control group (CG) by providing the cofactor of hydrogenase and accelerating electron transfer. Additionally, this synergistic strategy significantly (p < 0.01) increased the activities of hydrolases (e.g., protease and α-glucosidase), as well as key enzymes in acetate-type and butyrate-type fermentation pathways (e.g., acetate kinase and butyrate kinase), and enriched the biohydrogen-producing microbial community centered on Clostridium_sensu_stricto_1. This study systematically elucidated the synergistic strategy of TA pretreatment and NiCo₂O₄ NPs, which achieved dual-pathway reinforcement from substrate degradability to microbial metabolic activity. The findings are expected to provide theoretical support for developing efficient biohydrogen production technology from perishable organic solid waste. Full article

Spirit drink, known in Central and Eastern Europe as ‘okowita’ (its official designation is ‘spirit’), is obtained by distilling fermented plant raw materials. Unlike vodka, which is produced from highly purified ethyl alcohol of agricultural origin, ‘okowita’ is characterised by the preservation of the natural aromatic and flavour compounds originating from the raw material and produced during the process of alcoholic fermentation. The study aimed to assess the impact of production technology on the quality of potato spirits. The effects of the methods used for the pretreatment of raw material, starch hydrolysis and fermentation, and yeast strains were examined in relation to the fermentation efficiency and the chemical composition of the distillates. The yeast strains were the key factor determining fermentation efficiency. The SafSpirit and Pinnacle yeast strains provided the highest fermentation yields (85.0–97.7% of the theoretical), while the Ethanol Red strain provided the lowest yield (<83%). No advantage of separate hydrolysis and fermentation (SHF) over simultaneous saccharification and fermentation (SSF) was observed. A characteristic feature of potato distillates was their high isobutyl alcohol content, ranging from 557 to 1437 mg/L of 100% v/v alcohol, i.e., more than twice that of 3-methyl-1-butanol. Methanol concentrations remained below the limit specified in EU Regulation 2024/1143 (≤1000 g/hL of 100% v/v alcohol). The results are promising in terms of the potential for the production of craft potato spirit drinks. Full article

This study evaluates the enzymatic hydrolysis of pretreated corn cobs (PCCs) using a blend of commercial enzymes (Cellulase enzyme blend and Viscozyme L), followed by simultaneous saccharification and fermentation (SSF) with Mucor indicus DSM 2185 for ethanol production. A combination of 2% (vol vol⁻¹) Cellulase enzyme blend and 5.18% (vol vol⁻¹) Viscozyme L, corresponding to an enzyme loading of 48.9 FPU/g_PCCs, enabled near-complete hydrolysis of 40 g L⁻¹ PCCs within 6–48 h, achieving 92.66% total carbohydrate conversion into fermentable sugars. In SSF experiments conducted in Erlenmeyer flasks, optimal ethanol production in matrix nutrient medium (MNM) reached 14.95 g L⁻¹, with a conversion coefficient of 0.373 g g⁻¹ at 30 °C over a 48 h period. Scale-up of the bioprocess in a 1.5 L stirred-tank bioreactor at 30 °C resulted in an ethanol concentration of 16.46 g L⁻¹, a total carbohydrate conversion of 86.27%, and a substrate-to-ethanol conversion coefficient of 0.44 g g⁻¹ within 22 h. Minor secondary metabolites, including 0.88 g L⁻¹ xylitol and 0.26 g L⁻¹ glycerol, were also detected. Overall, the results demonstrate the potential of M. indicus in combination with commercial enzyme blends as a scalable strategy for industrial ethanol production. Full article

This study investigates the valorization of carrot discard, a carbohydrate-rich agricultural residue, for the production of 2,3-butanediol (2,3-BDO). The fermentation process was evaluated using two strains, Bacillus licheniformis DSM 8785 and Bacillus amyloliquefaciens DSM 7. Two process configurations were compared: separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF). Additionally, to determine substrate and product inhibition thresholds, fermentation assays were conducted in semi-defined media with glucose concentrations ranging from 20 to 120 g/L. The SHF strategy proved more effective than the SSF configuration. Under the SHF configuration, B. amyloliquefaciens demonstrated superior performance, yielding 16.7 g/L of 2,3-BDO. In contrast, B. licheniformis was notable for its high capacity for acetoin synthesis, producing 24.2 g/L of acetoin in addition to 10.9 g/L of 2,3-BDO. Therefore, these findings demonstrate that carrot discard is a viable feedstock for the co-production of 2,3-BDO and acetoin. Full article

The textile industry generates millions of tons of waste annually, posing significant environmental challenges. Addressing this issue, our study explores a sustainable biotechnological approach to convert cotton textile waste into valuable bioproducts. We evaluated the potential of Corynebacterium glutamicum ATCC 21492 for the production of L-lysine and other amino acids using glucose derived from cotton textile waste. Two experimental strategies were implemented: Sequential Hydrolysis and Fermentation (SHF) and Simultaneous Saccharification and Fermentation (SSF). In SHF, optimization of initial glucose concentration, temperature, and inoculum size led to the highest L-lysine concentration of 2.38 g/L under conditions of 45 g/L glucose, 35 °C, and 2% inoculum. The production of L-lysine, along with varying proportions of other amino acids such as alanine, threonine, methionine, and leucine, was significantly influenced by these parameters. In SSF, the highest L-lysine yield of 3.10 mg/g untreated cotton was achieved at 14% cotton loading, 7% enzyme dose, 35 °C, and 10% inoculum concentration, corresponding to an L-lysine concentration of 0.5 g/L. This reduced concentration, compared to SHF, is primarily attributed to limitations in cotton hydrolysis under the studied conditions. Nevertheless, C. glutamicum utilized alternative carbon sources present in the culture medium, leading to a diversified amino acid profile in the final product. These findings support the feasibility of textile waste bioconversion using C. glutamicum and highlight its potential as a sustainable platform for amino acid production, aligning with circular economy principles and contributing to the reduction of the textile industry’s environmental impact. Full article

This study developed a solid-state fermentation system based on Trichoderma harzianum, which significantly enhanced the nutritional value of distiller’s grain (DG) feed through a multi-stage synergistic treatment process. During the cellulase production phase, rice husk was used as an auxiliary material, and specific degradation of DGs was effectively enhanced. Through optimization using response surface methodology, the optimal enzyme production conditions were determined. The filter paper enzyme activity reached a peak of 1.45 U/gds (enzyme activity per gram of dry substrate) when the moisture content was 53%, the fermentation time was 3 days, and the Tween-80 dosage was 0.015 mL/g (dry weight basis). Under these conditions, the crude enzyme solution was used to hydrolyze DGs. Compared to original DGs, the content of reducing sugars increased by 10.75%. In the stage of protein production, segmented hydrolysis fermentation (SHF) and simultaneous saccharification fermentation (SSF) processes were employed using yeast. The results showed that SSF pathway showed better performance, and the true protein content reached 15.16% after 11 days, an increase of 41.5% compared to the control. Finally, through secondary fermentation regulated by Lactobacillus fermentum, the flavor of the feed was significantly improved. This study innovatively integrated bio-enzymatic hydrolysis and multi-strain synergistic fermentation technologies, providing a novel strategy for the efficient and sustainable production of protein feed based on DGs. Full article

This study explored innovative approaches to produce ethanol and xylitol from sugarcane bagasse using a hydrodynamic cavitation-assisted photo-Fenton process as the pretreatment, and yeast co-culture for hydrolysate fermentation. Pretreatment conditions were optimized (20 mg/L of iron sulfate, pH 5.0, and reaction time of 14 min) resulting in glucan and xylan hydrolysis yields of 96% and 89%, respectively. The hydrolysate produced under these conditions was fermented using a co-culture of Saccharomyces cerevisiae IR2 (an ethanol-producing strain) and Candida tropicalis UFMGBX12 (a xylitol-producing strain). Optimal co-culture conditions consisted of using an inoculum concentration of 1.5 g/L for each yeast strain. After 36 h of fermentation, ethanol and xylitol concentrations reached 20 g/L and 13 g/L, respectively. These results demonstrate the potential of combining hydrodynamic cavitation-assisted photo-Fenton pretreatment with co-culture fermentation to simultaneously produce ethanol and xylitol. This strategy presents a promising approach for enhancing the efficiency of lignocellulosic biorefineries. Full article

This study aims to identify the best conditions for liquid hot water pretreatment (LHW) of sweet stalk sorghum and the optimization method using the response surface method (RSM) with varying parameters, including temperature, reaction time, and acid catalysts, to enhance the enzymatic hydrolysis of pretreated sweet stalk sorghum. This study presents a novel approach by optimizing LHW pretreatment using RSM to maximize the glucose yield and minimize sugar degradation, in contrast to the widely used method of sulfuric acid hydrolysis combined with SSF. The goal is to achieve the highest glucose yield for ethanol production under optimal conditions. The results show that after the LHW pretreatment under optimal conditions, the optimal actual values have the highest glucose yield of 91.09% in a solid fraction at a sulfuric acid catalyst concentration of 0.90% with a pretreatment temperature of 110 °C for 90 min. The results of the statistical analysis of the glucose yield show an R-squared value of 0.9964 or 99.64%, which is statistically significant. In addition, the optimized pretreatment conditions significantly improved the accessibility of the enzyme. Pretreatment for ethanol production in sweet stalk sorghum samples was carried out with an H₂SO₄ catalyst concentration of 0.90% using the SSF method with the yeast strain S. cerevisiae. The results show that during the fermentation period of 0–96 h, the maximum ethanol concentration of 23.1 g/L occurred at 72 h under 25 FPU/g substrate at pH 4.8 and decreased 72 h after fermentation. In conclusion, sweet stalk sorghum is a promising candidate for ethanol production due to its high glucose yield and efficient enzymatic hydrolysis, making it a viable alternative for biomass-based energy production. Full article

High potential is attributed to the concomitant use of probiotics and prebiotics in a single food product, called “synbiotics”, where the prebiotic component distinctly favours the growth and activity of probiotic microbes. This study implemented a detailed comparison between the prebiotic effect of Fructooligosaccharides (FOSs) and Raffinose family oligosaccharides (RFOs) on the viable count of bacteria, hydrolysis into monosaccharides, the biosynthesis of short-chain fatty acids and sensory attributes of soymilk fermented with 1% (v/v) co-cultures of Lacticaseibacillus rhamnosus JCM1136 and Weissella confusa 30082b. The highest viable count of 1.21 × 10⁹ CFU/mL was observed in soymilk with 3% RFOs added as a prebiotic source compared with MRS broth with 3% RFOs (3.21 × 10⁸) and 3% FOS (6.2 × 10⁷ CFU/mL) when replaced against glucose in MRS broth. Raffinose and stachyose were extensively metabolised (4.75 and 1.28-fold decrease, respectively) in 3% RFOs supplemented with soymilk, and there was an increase in glucose, galactose, fructose (2.36, 1.55, 2.76-fold, respectively) in soymilk supplemented with 3% FOS. Synbiotic soymilk with 3% RFOs showed a 99-fold increase in methyl propionate, while the one supplemented with 3% FOS showed an increase in methyl butyrate. The highest acceptability based on the sensory attributes was for soymilk fermented with 2% RFOs + 2% FOS + 2% table sugar + 1% vanillin (7.87 ± 0.52) with high mouth feel, product consistency, taste, and flavour. This study shows that the simultaneous administration of soy with probiotic bacteria and prebiotic oligosaccharides like FOSs and RFOs enhance the synergistic interaction between them, which upgraded the nutritional and sensory quality of synbiotic soymilk. Full article

The enzymatic hydrolysis of lignocellulose is often hindered by the glucose-mediated inhibition of β-glucosidases, a major bottleneck in industrial cellulose degradation. Identifying novel glucose-tolerant β-glucosidases is essential for enhancing saccharification efficiency. In this study, we cloned and heterologously expressed a novel β-glucosidase, RpBgl8, from the termite Reticulitermes perilucifugus in Escherichia coli. Sequence and structural analyses classified RpBgl8 as a glycoside hydrolase family 1 enzyme. The purified enzyme exhibited optimal activity at 45 °C and pH 7.0, with broad stability across pH 4.0–8.0. Notably, RpBgl8 demonstrated high tolerance to lignocellulose-derived inhibitors and organic solvents, maintaining 100% activity in 15% ethanol. Furthermore, RpBgl8 exhibited outstanding glucose tolerance, retaining 100% activity at 2.5 M glucose and 82% activity at 4.0 M glucose—outperforming most previously reported β-glucosidases. A structural analysis revealed a narrow, hydrophobic substrate pocket, with residue F124 at the glycone-binding site critical for minimizing glucose accumulation. The F124W mutation significantly reduced glucose tolerance, confirming that hydrophobic interactions at the active site mitigate inhibition. These findings establish RpBgl8 as a promising candidate for high-solid biomass processing and simultaneous saccharification and fermentation applications, highlighting termites as underexplored sources of biocatalysts with unique industrial potential. Full article

Bioethanol is a renewable, environmentally-friendly biofuel conventionally produced through the alcoholic fermentation of sugary or starch-rich substrates by microorganisms, commonly Yeast Saccharomyces cerevisiae. Intermediates of industrial wheat flour wet milling processing to starch, such as A-starch and B-starch milk, are cost-effective, abundant, and non-seasonal feedstocks for bioethanol production. This study evaluates the bioethanol production from wheat A-starch and B-starch milk and mixtures of these two substrates in different ratios (1:3, 1:1, and 3:1) using two cold hydrolysis procedures at 65 °C: (i) simultaneous liquefaction and saccharification (SLS) followed by fermentation, and (ii) liquefaction by alpha-amylase followed by simultaneous saccharification and fermentation (SSF). The results demonstrated that SSF and SLS are equally efficient procedures for reaching a high ethanol yield of 53 g per 100 g of starch and 93% of starch conversion to ethanol for all investigated substrates. Lower levels of non-starch components in A-starch milk, which typically contribute to volatile by-product formation, allowed clear distillate profiles in terms of and lower content of aldehydes, methanol, and volatile acidity, enhancing ethanol distillate purity compared to B-starch milk. Mixing high-quality A-starch milk with low-cost B-starch milk enables higher ethanol yield, improved distillate quality, and energy savings for efficient industrial-scale applications. Full article

Succinic acid is applied in many chemical industries in which it can be produced through microbial fermentation using lignocellulosic biomasses. Mixed-waste office paper (MWOP) containing lignocellulosic fibers is enormously generated globally. MWOP is recycled into toilet paper and cardboard, but the recovery process is costly. The reuse of MWOP to alternatively produce succinic acid is highly attractive. In this study, pretreatment of MWOPs with 1% (v/v) H₂SO₄ at 121 °C for 20 min was found to be optimal. The optimal conditions for the enzymatic hydrolysis of H₂SO₄-pretreated MWOP (AP-MWOP) were at 50 °C, with cellulase loading at 80 PCU/g AP-MWOP. This resulted in the highest glucose (22.46 ± 0.15 g/L) and xylose (5.11 ± 0.32 g/L). Succinic acid production via separate hydrolysis and fermentation (SHF) by Escherichia coli KJ122 reached 28.19 ± 0.98 g/L (productivity of 1.17 ± 0.04 g/L/h). For simultaneous saccharification and fermentation (SSF), succinic acid was produced at 24.58 ± 2.32 g/L (productivity of 0.82 ± 0.07 g/L/h). Finally, succinic acid at 51.38 ± 4.05 g/L with yield and productivity of 0.75 ± 0.05 g/g and 1.07 ± 0.08 g/L/h was achieved via fed-batch pre-saccharified SSF. This study not only offers means to reuse MWOP for producing succinic acid but also provides insights for exploiting other wastes to high-value succinic acid, supporting environmental sustainability and zero-waste society. Full article

The integrated production of ethanol fuel through the simultaneous use of various by-products and waste materials is an intriguing concept, as it maximizes the raw material potential while addressing the challenge of managing waste biomass from different technological processes. The efficient utilization of lignocellulosic waste depends on employing a pretreatment method that enhances the susceptibility of structural polysaccharides to hydrolysis. The aim of the study was to assess the possibility of the simultaneous use of corn stillage biomass and beet molasses as raw materials for the production of ethanol fuel. The research focused on optimizing the process conditions for the acid pretreatment of stillage biomass and the enzymatic hydrolysis of cellulose and evaluating the effectiveness of two fermentation strategies: SHF (Separate Hydrolysis and Fermentation) and SSF (Simultaneous Saccharification and Fermentation). The highest hydrolysis susceptibility was observed in biomass pretreated with 2% v/v H₃PO₄ for 30 min at 121 °C. The maximum glucose concentration of about 12 g/L (hydrolysis efficiency about 35.5%) was achieved even with the lowest enzyme dose, i.e., 7.5 FPU per gram of biomass. The yeast also showed high fermentation activity in media prepared from stillage biomass and molasses, producing about 50 g/L of ethanol regardless of the fermentation strategy used. The complete fermentation of carbohydrates assimilated by yeast confirmed the complementarity of the two raw materials used to prepare fermentation media, emphasizing the high potential of the proposed technological solution for ethanol fuel production. Full article

Steam explosion (SE) is an effective lignocellulose pretreatment technology for second-generation L-lactic acid (L-LA) production. In this study, targeted to produce high-concentration L-LA from corn stover (CS), the fed-batch simultaneous saccharification and fermentation (SSF) of acidic, SE-pretreated CS was developed and demonstrated in a 5 L scale bioreactor under non-strict conditions (without detoxification and sterilization). The results indicated that the fed-batch SSF, with a simple pH control, realized a higher tolerance of the strains to the toxic by-products of hydrolysate, in comparison to the conventional sequential hydrolysis and fermentation (SHF), allowing for 153.8 g L⁻¹ of L-LA production, along with a productivity of 1.83 g L⁻¹ h⁻¹ in a system with a total of 40% (w/v) solid loading. The mass balance indicated that up to 449 kg of L-LA can be obtained from 1 t of dried CS. It exhibited obvious superiorities and laid down a solid foundation for the industrialization of second-generation L-LA production. Full article