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Summary: Sufu, a traditional Chinese fermented soybean food, had its flavour and quality influenced by the specific strains and fermentation environment. To investigate how microbial community succession affects the volatile aroma substances of Mucor racemosus sufu during fermentation, the microbial community structure using high‐throughput sequencing (HTS) technology was analysed. Additionally, volatile flavour compounds using solid‐phase microextraction gas chromatography mass spectrometry (SPME‐GC–MS) were detected. Throughout the pre‐fermentation, salting, and post‐fermentation stages, the changes in the microbial communities over time and space due to environmental variations were observed. The colony compositions at the phylum and genus levels were also analysed. The results revealed that Proteobacteria and Actinobacteria were the dominant bacterial phyla in the final fermented product. Furthermore, several microorganisms associated with flavour substances were identified, such as Lactobacillus, Pseudomonas, Wescheria, Hyphomyces, Candida, and Pichia. These microorganisms primarily influenced the synthesis of alcohols and acids, contributing to the overall flavour profile of the sufu. In the analysis of the final product, it identified fifty‐four volatile flavour compounds, including alcohols, esters, phenolic acids, aldehydes, ketones, ether, alkenes, and other compounds. These findings have important implications for isolating specific strains, enhancing flavour, and providing a solid foundation for optimising and ensuring the quality of sufu. [ABSTRACT FROM AUTHOR]

Abstract: Efficient conversion of wheat straw wastes into biohydrogen gas by cow dung compost was reported for the first time. Batch tests were carried out to analyze influences of several environmental factors on biohydrogen production from wheat straw wastes. The performance of biohydrogen production using the raw wheat straw and HCl pretreated wheat straw was then compared in batch fermentation tests. The maximum cumulative hydrogen yield of 68.1mlH2/gTVS was observed at 126.5h, the value is about 136-fold as compared with that of raw wheat straw wastes. The maximum hydrogen production rate of 10.14mlH2/gTVSh was obtained by a modified Gompertz equation. The hydrogen content in the biogas was 52.0% and there was no significant methane observed in this study. In addition, biodegradation characteristics of the substrate were also discussed. The experimental results showed that the pretreatment of the substrate plays a key role in the conversion of the wheat straw wastes into biohydrogen by the composts generating hydrogen. [Copyright &y& Elsevier]

Abstract: The cellulosic hydrogen production from cornstalk based on the integrating dilute acid with enzymatic hydrolysis was investigated using response surface methodology (RSM). The dilute acid pretreatment of cornstalk with the concentration of 1.5% H2SO4, 121 °C and 60 min was found to be most effective in the first prehydrolysis stage. Thereafter, the process parameters of enzymatic hydrolysis of the solid residue, which derived from acid-pretreated cornstalk, were further optimized by a three factor-five level central composite design (CCD) with temperature (X1 ), pH (X2 ), and enzyme loading (X3 ) as the independent variables. The optimal parameters of enzymatic hydrolysis of substrate were observed to be 52 °C of temperature, pH 4.8 and 9.4 IU/g of enzyme loading. In this case, the total soluble sugar obtained in the hydrolysis stages was 562.1 ± 6.9 mg/g-TVS, and the maximum hydrogen yield from cornstalk by anaerobic mixed microflora was 209.8 ml/g-TVS. Biodegradation mechanism of cornstalk for hydrogen production was further discussed based on analyzing changes in the physical structure and chemical composition of cornstalk during the hydrolysis and fermentation processes. [Copyright &y& Elsevier]

Abstract: Strategies were adopted to cost-efficiently produce cellulose-hydrogen by anaerobic fermentation in this paper. First, cellulase used for hydrolyzing cellulose was prepared by solid-state fermentation (SSF) on cheap biomass from Trichoderma viride. Several cultural conditions for cellulase production on cheap biomass such as moisture content, inoculum size and culture time were studied. And the components of solid-state medium were optimized using statistical methods to further improve cellulase capability. Second, the crude cellulase was applied to cellulose-hydrogen process directly. The maximal hydrogen yield of 122 ml/g-TVS was obtained at the substrate concentration of 20 g/L and cultured time of 53 h. The value was about 45-fold than that of raw corn stalk wastes. The hydrogen content in the biogas was 44–57%(v/v) and there was no significant methane gas observed. [Copyright &y& Elsevier]

In this paper, the high concentration of corn stalk (60 g/L) was employed as feedstock to produce bio-hydrogen and methane by combining hydrogen fermentation and anaerobic digestion. In the first stage of hydrogen fermentation, the effects of several key parameters, such as strain enhancement technique, cetyl trimethyl ammonium bromide (CTAB), NH 4 HCO 3 on hydrogen production from cornstalk were investigated and optimized. The maximum hydrogen yield of 79.8 ± 1.5 ml H 2 /g-TS and hydrogen production rate of 3.78 ml/g-cornstalk h was observed at fixed acidizing cornstalk of 60 g/L, strains Bacillus sp . FS2011 dosage of 10%(v/v), CTAB of 30 mg/L, NH 4 HCO 3 of 1.2 g/L and initial pH of 7.5 ± 0.5 at 36 ± 1 °C, respectively. In the second stage of anaerobic digestion, the effluent from hydrogen production bio-reactor was further employed as the feedstock to produce methane by methanogenic bacteria, the maximum methane yield of 227 ± 2.5 ml CH 4 /g-COD and COD removal rate of 95 ± 1% was recorded. The interesting observations were that the total amount of the organic wastewater produced in a higher substrate concentration (60 g/l) by hydrogen fermentation was reduced by about two-thirds compared with that of traditional low substrate concentration (≤20 g/l). [ABSTRACT FROM AUTHOR]

The low conversion efficiency of substrate is one of the main bottlenecks in dark fermentation for bio-H2 production. Herein, an enhanced H2 yield from corn stalk was achieved by integrating dark fermentation and single chamber microbial electrolysis cells (MECs). In the dark fermentation stage, a H2 yield of 129.8 mL H2/g-corn stalk and an average H2 production rate of 1.73 m3/m3 d were recorded at 20 g/L of corn stalk and initial pH 7.0. The effluent from dark fermentation was diluted and further employed as feedstock to generate H2 by MECs. A H2 yield of 257.3 mL H2/g-corn stalk, an HPR of 3.43 ± 0.12 m3/m3 d and an energy efficiency of 166 ± 10% were obtained with the effluent COD of 3995.5 mg/L under 0.8 V applied voltage. During MECs operation stage, about 90 ± 2% of acetate was converted to H2 and the corresponding COD removal reached 44 ± 2% in MECs. Overall, the H2 yield can reach 387.1 mL H2/g-corn stalk by integrating dark fermentation and MECs, which had nearly tripled as against that of dark fermentation. [ABSTRACT FROM AUTHOR]

Abstract: A new fermentative hydrogen-producing strain FS2011 was isolated from an effluent of bio-hydrogen production reactor, and identified as Bacillus amyloliquefaciens on the basis of 16S rDNA gene sequence. The strain could utilize various carbon and nitrogen sources to produce hydrogen in a broad range of initial pH (5.29–7.38). Phosphate buffer concentration and fermentation temperature significantly affected hydrogen production and cell growth. The maximum hydrogen yield of 2.26 mol/mol was observed at glucose concentration of 10 g/l, beef extract concentration of 2 g/l, initial pH 6.98, phosphate buffer of 20 mmol/l, and 35 °C, indicating FS2011 was a high-efficiency hydrogen-producing bacterium. [Copyright &y& Elsevier]

Abstract: The bio-hydrogen production potential from corn stalk was significantly affected by microwave irradiation pretreatment of cow dung compost in batch tests. The maximum hydrogen yield of 144.3 ml/g-corn stalk and hydrogen production rate of 3.6 ml/g-corn stalk h−1 were observed using the pretreated compost by microwave radiation of 1.5 min at fixed Na2CO3 dosage of 800 mg/l, Fe dosage of 400 mg/l, substrate concentration of 20 g/l, which increased about 99.6% and 85.2% compared with that of the control. The effects of microwave irradiation on microbial characteristics were further discussed by Atomic Force Microscope (AFM), determination of protein content and PCR-DGGE. The four dominant hydrogen-producing strains had been isolated and confirmed to be Bacillus amyloliquefaciens, Bacillus licheniformis, Bacillus subtilis and Enterococcus faecium, respectively. The diversity and symbiosis relations of the mixed bacteria were also observed in fermentation hydrogen production process. [Copyright &y& Elsevier]

Abstract: The effects of pretreatment method of cow dung compost, which was employed as natural hydrogen bacteria source, on the microbial community, population distribution of microbes and hydrogen production potential were investigated in the batch tests. The maximum hydrogen yield of 290.8 mL/L-culture appeared in the pretreated method A (infrared drying) by dark fermentation. The pretreated method of compost significantly affected microbial succession, population distribution of microbes. Both Clostridium sp. and Enterobacter sp. were found to be two species of preponderant hydrogen-producing bacteria, the next best was Bacteroides sp. and Veillonella sp., the last was Lactobacillus sp. and Streptococcus sp., which were also essential. The results showed that the mutualism and symbiosis relations of the mixed bacteria played a critical role in hydrogen fermentation process. [Copyright &y& Elsevier]

Abstract: Effects of pretreatment of natural bacterial source and raw material on biohydrogen production in fermentative biohydrogen production process were investigated systematically. Biohydrogen production from stale corn slurry was found to be feasible and effective by A1 (water soak) pretreated compost and B1 (gelatinization) pretreated stale corn. The results were further confirmed by the verification test with working volume of 8 L, in which the maximum hydrogen yield of 262 mL H2/g-substrate, hydrogen production rate of 39 mL/g h−1 and the corresponding hydrogen content of 50% was observed at fixed substrate concentration of 10 g/L, working pH 5.0–5.5 and 36 ± 1 °C. The effluent was mostly composed of acetate and butyrate. Subsequently, two new hydrogen producing strains were isolated from the effluent sludge in the running bioreactor, and they were preliminarily identified as Clostridium and Enterobacter, respectively, according to the routine screening examinations. [Copyright &y& Elsevier]

Abstract: The key process parameters of solid state enzymolysis for the generation of soluble sugar (SS) and bio-hydrogen production from corn stalk were optimized by the response surface methodology (RSM) based on a three factor-five level central composite design (CCD), respectively. The result showed that the optimal solid state enzymolysis condition from corn stalk was 47.7 °C, SCED of 0.054 g/g and 10.3 days for the maximum SS yield of 526 mg/g-TVS. Correspondingly, the optimal enzymolysis conditions from corn stalk appeared at 46.3 °C, SCED of 0.049 g/g and 7.5 days for the maximum hydrogen yield of 205.5 mL/g-TVS from the hydrolyzed substrate by the next dark fermentation. In addition, the bio-hydrogen production mechanism from corn stalk was preliminary investigated by XRD and SEM analyses. The results suggested that the solid state enzymolysis of substrate played a vital role in the effective conversion of corn stalk into bio-hydrogen by dark fermentation. [Copyright &y& Elsevier]

Abstract: A hydrogen producing strain F.P 01 was newly isolated from cow dung sludge in an anaerobic bioreactor. The strain F.P 01 was a mesophilic and facultative anaerobic bacterium, which exhibited gram-negative staining in both the exponential and stationary growth phases, and a regular long rod-shaped bacteria with the size of 0.6–0.9 μm × 1.2–2.5 μm, and also could biodegrade a variety of carbohydrates such as glucose, xylose, maltose, etc. The effects of important process parameters on hydrogen producing of F.P 01 were further investigated from hydrogen fermentation of maltose by strain F.P 01, including substrate concentration, medium pH, etc. And the results showed that hydrogen production potential and hydrogen production rate from maltose of this strain F.P 01 was180 mLH2/g-maltose and 4.0 mLH2/h, respectively. The corresponding hydrogen concentration of 58–73% was also be observed. Both butyric acid and acetic acid as main by-product was left in the reactor. [Copyright &y& Elsevier]