title: Enhanced poly(γ-glutamic acid) production by H2O2-induced reactive oxygen species in the fermentation of Bacillus subtilis NX-2.
abstract: Effects of reactive oxygen species (ROS) on cell growth and poly(γ-glutamic acid) (γ-PGA) synthesis were studied by adding hydrogen peroxide to a medium of Bacillus subtilis NX-2. After optimizing the addition concentration and time of H2O2, a maximum concentration of 33.9 g/L γ-PGA was obtained by adding 100 µM H2O2to the medium after 24 H. This concentration was 20.6% higher than that of the control. The addition of diphenyleneiodonium chloride (ROS inhibitor) can interdict the effect of H2O2-induced ROS. Transcriptional levels of the cofactors and relevant genes were also determined under ROS stress to illustrate the possible metabolic mechanism contributing to the improve γ-PGA production. The transcriptional levels of genes belonging to the tricarboxylic acid cycle and electron transfer chain system were significantly increased by ROS, which decreased the NADH/NAD+ratio and increased the ATP levels, thereby providing more reducing power and energy for γ-PGA biosynthesis. The enhanced γ-PGA synthetic genes also directly promoted the formation of γ-PGA. This study was the first to use the ROS control strategy for γ-PGA fermentation and provided valuable information on the possible mechanism by which ROS regulated γ-PGA biosynthesis in B. subtilis NX-2.
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing, People's Republic of China.|College of Food Science and Light Industry, Nanjing Tech University, Nanjing, People's Republic of China.
authors.forename: Bao
authors.initials: B
authors.lastname: Tang
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing, People's Republic of China.|College of Food Science and Light Industry, Nanjing Tech University, Nanjing, People's Republic of China.
authors.forename: Dan
authors.initials: D
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing, People's Republic of China.|College of Food Science and Light Industry, Nanjing Tech University, Nanjing, People's Republic of China.
authors.forename: Sha
authors.initials: S
authors.lastname: Li
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing, People's Republic of China.|College of Food Science and Light Industry, Nanjing Tech University, Nanjing, People's Republic of China.
authors.forename: Zongqi
authors.initials: Z
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing, People's Republic of China. fengxiaohai@njtech.edu.cn.|College of Food Science and Light Industry, Nanjing Tech University, Nanjing, People's Republic of China. fengxiaohai@njtech.edu.cn.
authors.forename: Xiaohai
authors.initials: X
authors.lastname: Feng
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing, People's Republic of China. xuh@njtech.edu.cn.|College of Food Science and Light Industry, Nanjing Tech University, Nanjing, People's Republic of China. xuh@njtech.edu.cn.
authors.forename: Hong
authors.initials: H
authors.lastname: Xu
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D001412:Bacillus subtilis / Q000166:cytology / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D019149:Bioreactors / Q000382:microbiology; D001709:Biotechnology / Q000379:methods*; D049109:Cell Proliferation / Q000187:drug effects; D002952:Citric Acid Cycle / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005285:Fermentation / Q000187:drug effects*; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D009243:NAD / Q000378:metabolism; D009861:Onium Compounds / Q000494:pharmacology; D010088:Oxidoreductases / Q000235:genetics; D011099:Polyglutamic Acid / Q000031:analogs & derivatives* / Q000096:biosynthesis; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D009861:Onium Compounds; C511775:poly(gamma-glutamic acid); D009243:NAD; D011099:Polyglutamic Acid; C007517:diphenyleneiodonium; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide; D010088:Oxidoreductases
keywords: Bacillus subtilis NX-2; poly (γ-glutamic acid); reactive oxygen species; regulation; signal molecule; transcriptional level