Chinese rice wine making is a typical simultaneous saccharification and fermentation(SSF) process.During the fermentation process,temperature is one of the key parameters which decide the quality of Chinese rice wine....Chinese rice wine making is a typical simultaneous saccharification and fermentation(SSF) process.During the fermentation process,temperature is one of the key parameters which decide the quality of Chinese rice wine.To optimize the SSF process for Chinese rice wine brewing,the effects of temperature on the kinetic parameters of yeast growth and ethanol production at various temperatures were determined in batch cultures using a mathematical model.The kinetic parameters as a function of temperature were evaluated using the software Origin8.0.Combing these functions with the mathematical model,an appropriate form of the model equations for the SSF considering the effects of temperature were developed.The kinetic parameters were found to fit the experimental data satisfactorily with the developed temperature-dependent model.The temperature profile for maximizing the ethanol production for rice wine fermentation was determined by genetic algorithm.The optimum temperature profile began at a low temperature of 26 °C up to 30 h.The operating temperature increased rapidly to 31.9 °C,and then decreased slowly to 18 °C at 65 h.Thereafter,the temperature was maintained at18 °C until the end of fermentation.A maximum ethanol production of 89.3 g·L^(-1)was attained.Conceivably,our model would facilitate the improvement of Chinese rice wine production at the industrial scale.展开更多
The aim of this paper is to use the microsatellites to evaluate acid-tolerance in Saccharomyces(S.) cerevisiae. Microsatellites have been widely used as the molecular marker to classify and identify S. cerevisiae stra...The aim of this paper is to use the microsatellites to evaluate acid-tolerance in Saccharomyces(S.) cerevisiae. Microsatellites have been widely used as the molecular marker to classify and identify S. cerevisiae strains, analyze genetic relationships among strains, and reveal genetic diversity of S. cerevisiae populations. In this paper, 25 key microsatellites of S. cerevisiae from 44 industrial yeast strains are investigated in the medium withconcentration gradients of acetic acid. Based on the analysis of correlations between the key microsatellite loci repeat numbers and acid-tolerance of the strains, the allele size of 4P14 a and 10P13 is positively related to acid-tolerance(p ? 0.05), the allele size of AT-X, 4P1 a and 10P8 are significantly negatively related to acid-tolerance(p ? 0.01). The above results provide informations on the molecular biodiversity of S. cerevisiae strains and can be a theoretical guidance for molecular marker assisted selection.展开更多
(R)-1,3-butanediol is an important pharmaceutical intermediate, and the synthesis of(R)-1,3-butanediol using green biological methods has recently been of interest for industrial application. Here, a novel strain QC-1...(R)-1,3-butanediol is an important pharmaceutical intermediate, and the synthesis of(R)-1,3-butanediol using green biological methods has recently been of interest for industrial application. Here, a novel strain QC-1 that efficiently transforms 4-hydroxy-2-butanone to(R)-1,3-butanediol was isolated from soil samples. Based on morphological, physiological, and biochemical tests and 5.8 S-internal transcribed spacer sequencing, the strain was identified as Pichia kudriavzevii QC-1. The reaction conditions were optimized to 35 ℃, pH 8.0, rotation speed 200 rpm, and 6:5 mass ratio of glucose to 4-hydroxy-2-butanone. Evaluation of the effects of 4-hydroxy-2-butanone concentrations on yield and cell survival rate showed that 85.60 g·L^-1 product accumulated, with an enantiomeric excess of more than 99%, when 30 g·L^-14-hydroxy-2-butanone was added at 0, 10, and 30 h in a 3-L bioreactor. Thus, strain QC-1 showed excellent catalytic activity and stereoselectivity for the synthesis of(R)-1,3-butanediol from 4-hydroxy-2-butanone.展开更多
Seed germination of plants with various acid-resis tance display different responses to acid rain.To understand the reason why such differences occur,the effects of sim ulated acid rain(pH 2.5-5.0)on the activities of...Seed germination of plants with various acid-resis tance display different responses to acid rain.To understand the reason why such differences occur,the effects of sim ulated acid rain(pH 2.5-5.0)on the activities of peroxidase(POD)and catalase(CAT)during sced ger-mination of rice(O.sativa),wheat(T.aestivurm),and rape(B.chinensis var.oleifera)were investigated.R cesults indi-cated that the maximum change in activities of CAT and POD by acid rain treatment with different acidity and time in relation to the referent treatment without acid rain,was in the order:rice(28.8%,31.7%)<wheat(34.7%,48.3%)<rape(79.3%,50.0%).The pH level for which the treatment with acid rain did not cause signif-cant difference(p<0.05)was in the order:rice(3.5)>wheat(4.0)>rape(5.0).Moreover,the change in activity of POD was higher than that of CAT,which showed that POD was more sensitive to acid rain stress than CAT.The difference in the ability of POD and CAT in removing free radicals was one reason why the germina-tion indexes of these three species behaved differently.展开更多
Multispecies solid-state fermentation is a traditional processing technique for the traditional Chinese food,such as cereal vinegar,Baijiu,etc.Generally,few abundant and many rare microbes were involved in such proces...Multispecies solid-state fermentation is a traditional processing technique for the traditional Chinese food,such as cereal vinegar,Baijiu,etc.Generally,few abundant and many rare microbes were involved in such processes,and the necessity and roles of the latter are less studied.Here the co-occurrence patterns of abundant and rare bacterial community and abiotic factors infuencing their community assembly were investigated in acetic acid fermentation following starter inoculation,using Zhenjiang aromatic vinegar as a model system.Abundant taxa that contribute to the function of accumulating acid exhibited a ubiquitous distribution while the distribution of rare taxa along the fermentation process unraveled.The species composition of the rare taxa signifcantly altered,but abundant taxa were maintained after inoculation.Moreover,the diversity of rare taxa changed more signifcantly than that of abundant taxa.Both abundant and rare sub-communities,which were contributed more with species turnover than species richness,were demonstrated to be driven by pH,acetic acid,ammonium nitrogen,and ethanol.Stochastic processes regulated the assembly of both sub-communities,but more prominent on rare sub-communities.Co-occurrence network was more governed by rare sub-communities,and the co-variations between microbial communities were predominantly positive,implying that rare taxa played more important role in the fermentation stability and network robustness.Furthermore,seven network connectors were identifed,and three of them belonged to rare taxa.These microbes of diferent modules were enriched at particular phases of fermentation.These results demonstrate the ecological signifcance of rare bacteria and provide new insights into understanding the abiotic factors infuence microbial structure in traditional fermented foods.展开更多
D-amino acids,different from the ubiquitous L-amino acids,are recognized as the“unnatural”amino acids.The applications of D-amino acids have drawn increasing interest from researchers in recent years,and D-amino aci...D-amino acids,different from the ubiquitous L-amino acids,are recognized as the“unnatural”amino acids.The applications of D-amino acids have drawn increasing interest from researchers in recent years,and D-amino acids are widely used in various industries,including for food products,pharmaceuticals,and agricultural chemicals.Inspired by the prevalent appli-cations,many synthetic methods for D-amino acids have been developed,which are mainly divided into chemical synthetic methods and biosynthetic methods.Chemical synthesis of D-amino acids has a variety of disadvantages such as multiple reaction steps,low yields,low reaction rates,and difficulties in product extraction.Thus,biosynthetic methods utilizing enzymes are attracting increasing attention because they are more energy-saving and environmentally friendly compared to traditional chemical synthesis.Among all enzymatic methods,multi-enzymatic cascade catalytic methods have significant advantages,such as lower costs,no need for intermediate separation,and higher catalytic efficiency,which is ascribed to the spatial proximity of biocatalysts.In this review,advances in multi-enzyme cascade catalytic systems as well as chemo-enzymatic approaches to synthesize D-amino acids are discussed.展开更多
The asymmetric hydroxylation of inactive carbon atoms in organic compounds remains an important reaction in the industrial synthesis of valuable chiral compounds.Fe(II)and 2-ketoglutarate-dependent dioxygenases(Fe/2-k...The asymmetric hydroxylation of inactive carbon atoms in organic compounds remains an important reaction in the industrial synthesis of valuable chiral compounds.Fe(II)and 2-ketoglutarate-dependent dioxygenases(Fe/2-kg DOs)are the largest known subgroups of mononuclear nonheme-Fe(II)-dependent oxygenases,catalyzing various oxidation reactions of C-H bonds.Recent developments in Fe/2-kg DO-related researches have coupled concepts from bioinformatics,synthetic biology,and computational biology to establish effective biotransformation systems.The most well-studied and characterized activ-ity of the Fe/2-kg DOs is substrate hydroxylation,with regard to which mechanistic studies involving the Fe center assist in engineering the protein frameworks of these enzymes to obtain the desired catalytic enhancements.Amino acids are typical substrates of Fe/2-kg DOs and are usually converted into hydroxyl amino acids,which are widely used as intermediates in pharmaceutical and fine chemical industries.Herein,we have reviewed prior structural and mechanistic studies on Fe/2-kg DOs,as well as studies on the Fe/2-kg DO-mediated selective C-H oxidation process for selective hydroxyl amino acid synthesis,which will further our journey along the promising path of building complexity via C-H bond oxidation.Further,new bioinformatics techniques should be adopted with structure-based protein rational design to mine sequence databases and shrink mutant libraries to produce a diverse panel of functional Fe/2-kg DOs capable of catalyzing targeted reactions.展开更多
基金Supported by the National Natural Science Foundation of China(21276111,21206053,61305017)the Programme of Introducing Talents of Discipline to Universities(B12018)+2 种基金Fundamental Research Funds for the Central Universities(JUSRP11558)the Natural Science Foundation of Jiangsu Province(no.BK20160162)the Fundamental Research Funds for the Central Universities(JUSRP51510)
文摘Chinese rice wine making is a typical simultaneous saccharification and fermentation(SSF) process.During the fermentation process,temperature is one of the key parameters which decide the quality of Chinese rice wine.To optimize the SSF process for Chinese rice wine brewing,the effects of temperature on the kinetic parameters of yeast growth and ethanol production at various temperatures were determined in batch cultures using a mathematical model.The kinetic parameters as a function of temperature were evaluated using the software Origin8.0.Combing these functions with the mathematical model,an appropriate form of the model equations for the SSF considering the effects of temperature were developed.The kinetic parameters were found to fit the experimental data satisfactorily with the developed temperature-dependent model.The temperature profile for maximizing the ethanol production for rice wine fermentation was determined by genetic algorithm.The optimum temperature profile began at a low temperature of 26 °C up to 30 h.The operating temperature increased rapidly to 31.9 °C,and then decreased slowly to 18 °C at 65 h.Thereafter,the temperature was maintained at18 °C until the end of fermentation.A maximum ethanol production of 89.3 g·L^(-1)was attained.Conceivably,our model would facilitate the improvement of Chinese rice wine production at the industrial scale.
基金Funded by Open Project Program of the Key Laboratory of Industrial Biotechnology,Ministry of Education,China(KLIBKF201102)the Fok Ying-Tong Education Foundation of China(No.131020)+2 种基金the program for New Century Excellent Talents in University(NCET-11-0665)the Fundamental Research Funds for the Central Universities(JUSRP51313B)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘The aim of this paper is to use the microsatellites to evaluate acid-tolerance in Saccharomyces(S.) cerevisiae. Microsatellites have been widely used as the molecular marker to classify and identify S. cerevisiae strains, analyze genetic relationships among strains, and reveal genetic diversity of S. cerevisiae populations. In this paper, 25 key microsatellites of S. cerevisiae from 44 industrial yeast strains are investigated in the medium withconcentration gradients of acetic acid. Based on the analysis of correlations between the key microsatellite loci repeat numbers and acid-tolerance of the strains, the allele size of 4P14 a and 10P13 is positively related to acid-tolerance(p ? 0.05), the allele size of AT-X, 4P1 a and 10P8 are significantly negatively related to acid-tolerance(p ? 0.01). The above results provide informations on the molecular biodiversity of S. cerevisiae strains and can be a theoretical guidance for molecular marker assisted selection.
基金Financial supports from the National Key R&D Program of China(2018YFC1604100)the National Natural Science Foundation of China(NSFC)[21676120,31872891]+8 种基金the 111 Project[111-2-06]the Highend Foreign Experts Recruitment Program[G20190010083]the Program for Advanced Talents within Six Industries of Jiangsu Province[2015-NY007]the National Program for Support of Top-notch Young Professionalsthe Fundamental Research Funds for the Central Universities[JUSRP51504]the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education InstitutionsTop-notch Academic Programs Project of Jiangsu Higher Education Institutionsthe Jiangsu Province“Collaborative Innovation Center for Advanced Industrial Fermentation”Industry Development Programthe National First-Class Discipline Program of Light Industry Technology and Engineering[LITE2018-09]。
文摘(R)-1,3-butanediol is an important pharmaceutical intermediate, and the synthesis of(R)-1,3-butanediol using green biological methods has recently been of interest for industrial application. Here, a novel strain QC-1 that efficiently transforms 4-hydroxy-2-butanone to(R)-1,3-butanediol was isolated from soil samples. Based on morphological, physiological, and biochemical tests and 5.8 S-internal transcribed spacer sequencing, the strain was identified as Pichia kudriavzevii QC-1. The reaction conditions were optimized to 35 ℃, pH 8.0, rotation speed 200 rpm, and 6:5 mass ratio of glucose to 4-hydroxy-2-butanone. Evaluation of the effects of 4-hydroxy-2-butanone concentrations on yield and cell survival rate showed that 85.60 g·L^-1 product accumulated, with an enantiomeric excess of more than 99%, when 30 g·L^-14-hydroxy-2-butanone was added at 0, 10, and 30 h in a 3-L bioreactor. Thus, strain QC-1 showed excellent catalytic activity and stereoselectivity for the synthesis of(R)-1,3-butanediol from 4-hydroxy-2-butanone.
基金This work was supported by the Foundation of State Planning Committee(No.GJX01100626)the Foundation of Science and Technology Committee of Jiangsu Province(Grant No.BG2001045)the Foundation from Key Laboratory of Industrial Biotechnology of Ministry of Education,Jiangnan University of China.
文摘Seed germination of plants with various acid-resis tance display different responses to acid rain.To understand the reason why such differences occur,the effects of sim ulated acid rain(pH 2.5-5.0)on the activities of peroxidase(POD)and catalase(CAT)during sced ger-mination of rice(O.sativa),wheat(T.aestivurm),and rape(B.chinensis var.oleifera)were investigated.R cesults indi-cated that the maximum change in activities of CAT and POD by acid rain treatment with different acidity and time in relation to the referent treatment without acid rain,was in the order:rice(28.8%,31.7%)<wheat(34.7%,48.3%)<rape(79.3%,50.0%).The pH level for which the treatment with acid rain did not cause signif-cant difference(p<0.05)was in the order:rice(3.5)>wheat(4.0)>rape(5.0).Moreover,the change in activity of POD was higher than that of CAT,which showed that POD was more sensitive to acid rain stress than CAT.The difference in the ability of POD and CAT in removing free radicals was one reason why the germina-tion indexes of these three species behaved differently.
基金This work was supported by National Key R&D Program of China(2018YFC1603800 and 2018YFC1603802)Natural Science Foundation of China(NSFC)(No.31771967)We thank Jiangsu Hengshun Vinegar Industry Co,Ltd,for the samples provided.
文摘Multispecies solid-state fermentation is a traditional processing technique for the traditional Chinese food,such as cereal vinegar,Baijiu,etc.Generally,few abundant and many rare microbes were involved in such processes,and the necessity and roles of the latter are less studied.Here the co-occurrence patterns of abundant and rare bacterial community and abiotic factors infuencing their community assembly were investigated in acetic acid fermentation following starter inoculation,using Zhenjiang aromatic vinegar as a model system.Abundant taxa that contribute to the function of accumulating acid exhibited a ubiquitous distribution while the distribution of rare taxa along the fermentation process unraveled.The species composition of the rare taxa signifcantly altered,but abundant taxa were maintained after inoculation.Moreover,the diversity of rare taxa changed more signifcantly than that of abundant taxa.Both abundant and rare sub-communities,which were contributed more with species turnover than species richness,were demonstrated to be driven by pH,acetic acid,ammonium nitrogen,and ethanol.Stochastic processes regulated the assembly of both sub-communities,but more prominent on rare sub-communities.Co-occurrence network was more governed by rare sub-communities,and the co-variations between microbial communities were predominantly positive,implying that rare taxa played more important role in the fermentation stability and network robustness.Furthermore,seven network connectors were identifed,and three of them belonged to rare taxa.These microbes of diferent modules were enriched at particular phases of fermentation.These results demonstrate the ecological signifcance of rare bacteria and provide new insights into understanding the abiotic factors infuence microbial structure in traditional fermented foods.
基金Financial supports from the National Natural Science Foundation of China(NSFC)(No.31872891)the 111 Project(No.111-2-06)+2 种基金the High-End Foreign Experts Recruitment Program(No.G20190010083)the National Program for Support of Top-Notch Young Professionals,the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions,Top-Notch Academic Programs Project of Jiangsu Higher Education Institutions,the Jiangsu Province“Collaborative Innovation Center for Advanced Industrial Fermentation”Industry Development Program,the Program for the Key Laboratory of Enzymes of Suqian(No.M201803)the National First-Class Discipline Program of Light Industry Technology and Engineering(No.LITE2018-09)are greatly appreciated.
文摘D-amino acids,different from the ubiquitous L-amino acids,are recognized as the“unnatural”amino acids.The applications of D-amino acids have drawn increasing interest from researchers in recent years,and D-amino acids are widely used in various industries,including for food products,pharmaceuticals,and agricultural chemicals.Inspired by the prevalent appli-cations,many synthetic methods for D-amino acids have been developed,which are mainly divided into chemical synthetic methods and biosynthetic methods.Chemical synthesis of D-amino acids has a variety of disadvantages such as multiple reaction steps,low yields,low reaction rates,and difficulties in product extraction.Thus,biosynthetic methods utilizing enzymes are attracting increasing attention because they are more energy-saving and environmentally friendly compared to traditional chemical synthesis.Among all enzymatic methods,multi-enzymatic cascade catalytic methods have significant advantages,such as lower costs,no need for intermediate separation,and higher catalytic efficiency,which is ascribed to the spatial proximity of biocatalysts.In this review,advances in multi-enzyme cascade catalytic systems as well as chemo-enzymatic approaches to synthesize D-amino acids are discussed.
基金Financial supports from the National Natural Science Foundation of China(NSFC)(No.21676120)the 111 Project(No.111-2-06)+5 种基金the High-End Foreign Experts Recruitment Program(No.G20190010083)the Program for Advanced Talents within Six Industries of Jiangsu Province(No.2015-NY-007)the National Program for Support of Top-Notch Young Professionals,the Fundamental Research Funds for the Central Universities(No.JUSRP51504)the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions,Top-Notch Academic Programs Project of Jiangsu Higher Education Institutions,the Jiangsu Province“Collaborative Innovation Center for Advanced Industrial Fermentation”Industry Development Program,the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX19_1833)the Program for the Key Laboratory of Enzymes of Suqian(No.M201803)the National First-Class Discipline Program of Light Industry Technology and Engineering(No.LITE2018-09)are greatly appreciated。
文摘The asymmetric hydroxylation of inactive carbon atoms in organic compounds remains an important reaction in the industrial synthesis of valuable chiral compounds.Fe(II)and 2-ketoglutarate-dependent dioxygenases(Fe/2-kg DOs)are the largest known subgroups of mononuclear nonheme-Fe(II)-dependent oxygenases,catalyzing various oxidation reactions of C-H bonds.Recent developments in Fe/2-kg DO-related researches have coupled concepts from bioinformatics,synthetic biology,and computational biology to establish effective biotransformation systems.The most well-studied and characterized activ-ity of the Fe/2-kg DOs is substrate hydroxylation,with regard to which mechanistic studies involving the Fe center assist in engineering the protein frameworks of these enzymes to obtain the desired catalytic enhancements.Amino acids are typical substrates of Fe/2-kg DOs and are usually converted into hydroxyl amino acids,which are widely used as intermediates in pharmaceutical and fine chemical industries.Herein,we have reviewed prior structural and mechanistic studies on Fe/2-kg DOs,as well as studies on the Fe/2-kg DO-mediated selective C-H oxidation process for selective hydroxyl amino acid synthesis,which will further our journey along the promising path of building complexity via C-H bond oxidation.Further,new bioinformatics techniques should be adopted with structure-based protein rational design to mine sequence databases and shrink mutant libraries to produce a diverse panel of functional Fe/2-kg DOs capable of catalyzing targeted reactions.