The objective of this work was to investigate the effect of six individual strains of fungi on the reduction of gossypol levels and nutritional value during solid substrate fen＇aentation of cottonseed meal （CSM）. S...The objective of this work was to investigate the effect of six individual strains of fungi on the reduction of gossypol levels and nutritional value during solid substrate fen＇aentation of cottonseed meal （CSM）. Six groups of disinfected CSM substrate were incubated for 48 h after inoculation with either of the fungi C. capsuligena ZD- 1, C. tropicalis ZD-3, S. cerevisae ZD-5, A. terricola ZD-6, A. oryzae ZD-7, or A. niger ZD-8. One not inoculated group （substrate） was used as a control. Levels of initial and final free gossypol （FG）, crude protein （CP）, amino acids （AA） and in vitro digestibility were assayed. The experiment was done in triplicate. The experimental results indicated that microbial fermentation could greatly decrease （P〈0.05） FG levels in CSM. The detoxification efficiency differed between the species of microorganisms applied. From the perspective of reducing CSM potential toxicity, C. tropicalis ZD-3 was most successful followed by S. cerevisae ZD-5 and A. niger ZD-8. They could reduce FG levels of CSM to 29.8, 63.07 and 81.50 mg/kg based on DM （dry matter）, respectively, and their detoxification rates were 94.57%, 88.51% and 85.16%, respectively. If crude protein, amino acids content and their in vitro digestibility were also taken into account, Aniger ZD-8 may be the best choice. The CP content of CSM substrate fermented by C. tropicalis ZD-3 and A. niger ZD-8 were improved by 10.76% and 22.24%; the TAA （total amino acids） contents were increased by 7.06% and 11.46%, and the EAA （essential amino acids） were raised by 7.77% and 12.64%, respectively. Especially, the levels of methionine, lysine and threonine were improved greatly （P〈0.05）. The in vitro CP digestibility of CSM fermented by C. tropicalis ZD-3 and A. niger ZD-8 was improved by 13.42% and 18.22%, the TAA were increased by 17.75% and 22.88%, and the EAA by 16.61% and 21.01%, respectively. In addition, the in vitro digestibility of methionine, lysine and threonine was also improved greatly （P〈0.05）.展开更多
The importance of microbial enzymes in pulp and paper manufacturing has grown significantly in the last two decades. Solid substrate fermentation (SSF) holds tremendous potential for the production of microbial enzyme...The importance of microbial enzymes in pulp and paper manufacturing has grown significantly in the last two decades. Solid substrate fermentation (SSF) holds tremendous potential for the production of microbial enzymes of commercial interest. SSF can be of special interest in those processes where the crude fermented product (whole SSF culture, in situ enzyme) may be used directly as the enzyme source. Xylanase preparations practically free of cellulase activity are especially useful for biobleaching of crude cellulose pulps. Thirty-nine Trichoderma isolates have been screened in SSF for xylanase production on hardwood oxygen-delignified soda-aq pulp as carbon source and enzyme inducer. Xylanase activities varied between 0 and 2200 IU/g dry matter (DM) of initial substrate. In most instances, the simultaneously produced cellulase levels were below 1.0 Filter Paper Unit (FPU) /g DM. The xylanase to cellulase activity ratio varied in the range of 5 to 3500. The three most promising isolates (TUB F-1647, TUB F-1658 and TUB F-1684) yielded xylanase activity of 2040, 1300 and 1500 IU/g DM xylanase, respectively, and 0.64, 0.43 and 0.43 FPU/g DM cellulase with a xylanase to cellulase activity ratio of 3200, 3000 and 3500, respectively. Wild strains F-1647, F-1658 and F-1684 were isolated from tree bark of Maldives, soils of Peru (last two), respectively. Medium optimization experiments to enhance the xylanase yield and to increase the xylanase to cellulase ratio have also been performed.展开更多
High-temperature Daqu is a crucial starter for Chinese Baijiu,yet how wheat substrate characteristics and MFH additives jointly influence microbial assembly and flavor metabolism remains unclear.Here,two wheat varieti...High-temperature Daqu is a crucial starter for Chinese Baijiu,yet how wheat substrate characteristics and MFH additives jointly influence microbial assembly and flavor metabolism remains unclear.Here,two wheat varieties with distinct physicochemical properties(WA and WC)were used to construct three Daqu systems:WA with MFH(QA),WA without MFH(QB),and WC with MFH(QC).We systematically tracked their physicochemical,mi-crobial,and flavor dynamics.The two wheat varieties differed significantly in moisture,reducing sugars,total starch,amylose,amylopectin,fat,and protein contents,driving distinct trajectories in Daqu physicochemical and enzymatic activities.Volatile profiling revealed distinct flavor profiles,with QC showing stronger accumulation of pyrazines and phenolic compounds.Amplicon sequencing indicated that substrate properties primarily drove microbial succession,whereas MFH addition more strongly influenced fungal community variation.Ecological modeling revealed that bacterial assembly in QC involved a greater stochastic contribution,whereas QA and QB were governed by deterministic environmental filtering.Integrated structural modeling and functional predic-tion analyses further suggested that these ecological divergences were associated with distinct flavor-related metabolic patterns,particularly phenylalanine-,pyrazine-,and ester-related pathways.Collectively,wheat substrate properties were identified as the primary ecological filter in Daqu fermentation,with MFH showing substrate-dependent modulatory effects.This study provides a theoretical basis for microbial regulation and flavor optimization in high-temperature Daqu production.展开更多
基金Project (No. 30471255) supported by the National Natural ScienceFoundation of China
文摘The objective of this work was to investigate the effect of six individual strains of fungi on the reduction of gossypol levels and nutritional value during solid substrate fen＇aentation of cottonseed meal （CSM）. Six groups of disinfected CSM substrate were incubated for 48 h after inoculation with either of the fungi C. capsuligena ZD- 1, C. tropicalis ZD-3, S. cerevisae ZD-5, A. terricola ZD-6, A. oryzae ZD-7, or A. niger ZD-8. One not inoculated group （substrate） was used as a control. Levels of initial and final free gossypol （FG）, crude protein （CP）, amino acids （AA） and in vitro digestibility were assayed. The experiment was done in triplicate. The experimental results indicated that microbial fermentation could greatly decrease （P〈0.05） FG levels in CSM. The detoxification efficiency differed between the species of microorganisms applied. From the perspective of reducing CSM potential toxicity, C. tropicalis ZD-3 was most successful followed by S. cerevisae ZD-5 and A. niger ZD-8. They could reduce FG levels of CSM to 29.8, 63.07 and 81.50 mg/kg based on DM （dry matter）, respectively, and their detoxification rates were 94.57%, 88.51% and 85.16%, respectively. If crude protein, amino acids content and their in vitro digestibility were also taken into account, Aniger ZD-8 may be the best choice. The CP content of CSM substrate fermented by C. tropicalis ZD-3 and A. niger ZD-8 were improved by 10.76% and 22.24%; the TAA （total amino acids） contents were increased by 7.06% and 11.46%, and the EAA （essential amino acids） were raised by 7.77% and 12.64%, respectively. Especially, the levels of methionine, lysine and threonine were improved greatly （P〈0.05）. The in vitro CP digestibility of CSM fermented by C. tropicalis ZD-3 and A. niger ZD-8 was improved by 13.42% and 18.22%, the TAA were increased by 17.75% and 22.88%, and the EAA by 16.61% and 21.01%, respectively. In addition, the in vitro digestibility of methionine, lysine and threonine was also improved greatly （P〈0.05）.
文摘The importance of microbial enzymes in pulp and paper manufacturing has grown significantly in the last two decades. Solid substrate fermentation (SSF) holds tremendous potential for the production of microbial enzymes of commercial interest. SSF can be of special interest in those processes where the crude fermented product (whole SSF culture, in situ enzyme) may be used directly as the enzyme source. Xylanase preparations practically free of cellulase activity are especially useful for biobleaching of crude cellulose pulps. Thirty-nine Trichoderma isolates have been screened in SSF for xylanase production on hardwood oxygen-delignified soda-aq pulp as carbon source and enzyme inducer. Xylanase activities varied between 0 and 2200 IU/g dry matter (DM) of initial substrate. In most instances, the simultaneously produced cellulase levels were below 1.0 Filter Paper Unit (FPU) /g DM. The xylanase to cellulase activity ratio varied in the range of 5 to 3500. The three most promising isolates (TUB F-1647, TUB F-1658 and TUB F-1684) yielded xylanase activity of 2040, 1300 and 1500 IU/g DM xylanase, respectively, and 0.64, 0.43 and 0.43 FPU/g DM cellulase with a xylanase to cellulase activity ratio of 3200, 3000 and 3500, respectively. Wild strains F-1647, F-1658 and F-1684 were isolated from tree bark of Maldives, soils of Peru (last two), respectively. Medium optimization experiments to enhance the xylanase yield and to increase the xylanase to cellulase ratio have also been performed.
基金support obtained from The National Key Research and Development Program of China(2022YFD2101401).
文摘High-temperature Daqu is a crucial starter for Chinese Baijiu,yet how wheat substrate characteristics and MFH additives jointly influence microbial assembly and flavor metabolism remains unclear.Here,two wheat varieties with distinct physicochemical properties(WA and WC)were used to construct three Daqu systems:WA with MFH(QA),WA without MFH(QB),and WC with MFH(QC).We systematically tracked their physicochemical,mi-crobial,and flavor dynamics.The two wheat varieties differed significantly in moisture,reducing sugars,total starch,amylose,amylopectin,fat,and protein contents,driving distinct trajectories in Daqu physicochemical and enzymatic activities.Volatile profiling revealed distinct flavor profiles,with QC showing stronger accumulation of pyrazines and phenolic compounds.Amplicon sequencing indicated that substrate properties primarily drove microbial succession,whereas MFH addition more strongly influenced fungal community variation.Ecological modeling revealed that bacterial assembly in QC involved a greater stochastic contribution,whereas QA and QB were governed by deterministic environmental filtering.Integrated structural modeling and functional predic-tion analyses further suggested that these ecological divergences were associated with distinct flavor-related metabolic patterns,particularly phenylalanine-,pyrazine-,and ester-related pathways.Collectively,wheat substrate properties were identified as the primary ecological filter in Daqu fermentation,with MFH showing substrate-dependent modulatory effects.This study provides a theoretical basis for microbial regulation and flavor optimization in high-temperature Daqu production.
