Enhanced production of poly-γ-glutamic acid via optimizing the expression cassette of Vitreoscilla hemoglobin in Bacillus licheniformis  

作　　者：Qing Zhang Yaozhong Chen Lin Gao Jian’gang Chen Xin Ma Dongbo Cai Dong Wang Shouwen Chen 

机构地区：[1]State Key Laboratory of Biocatalysis and Enzyme Engineering,Environmental Microbial Technology Center of Hubei Province,College of Life Sciences,Hubei University,Wuhan,430062,PR China [2]Wuhan Junan Biotechnology Co.Ltd.,Wuhan,China [3]Tobacco Research Institute,Chinese Academy of Agricultural Sciences,Qingdao,China

出　　处：《Synthetic and Systems Biotechnology》2022年第1期567-573,共7页合成和系统生物技术（英文）

基　　金：the National Natural Science Foundation of China(31972849);National Key Research and Development Program of China(2021YFC2101700);the Science and Technology Project of Hubei Tobacco Company(027Y2020-013).

摘　　要：Poly-γ-glutamic acid(γ-PGA)is a natural polymer with various applications,and its high-viscosity hinders ox-ygen transmission and improvement of synthesis level.Vitreoscilla hemoglobin(VHB)has been introduced into various hosts as oxygen carrier,however,its expression strength and contact efficiency with oxygen hindered efficient oxygen transfer and metabolite synthesis.Here,we want to optimize the expression cassette of VHB for γ-PGA production.Firstly,our results implied that γ-PGA yields were enhanced when introducing twin-arginine translocation(Tat)signal peptides(SP_(YwbN),SP_(PhoD) and SP_(TorA))into VHB expression cassette,and the best per-formance was attained by SP YwbN from Bacillus subtilis,theγ-PGA yield of which was 18.53% higher than that of control strain,and intracellular ATP content and oxygen transfer coefficient(K_(L)a)were increased by 29.71% and 73.12%,respectively,indicating that VHB mediated by SP YwbN benefited oxygen transfer and ATP generation forγ-PGA synthesis.Furthermore,four promoters were screened,and P vgb was proven as the more suitable promoter for VHB expression andγ-PGA synthesis,andγ-PGA yield of attaining strain WX/pPvgb-YwbN-Vgb was further increased to 40.59 g/L by 10.18%.Finally,WX/pPvgb-YwbN-Vgb was cultivated in 3 L fermentor for fed-batch fermentation,and 46.39 g/Lγ-PGA was attained by glucose feeding,increased by 49.26%compared with the initial yield(31.01 g/L).Taken together,this study has attained an efficient VHB expression cassette for oxygen transfer andγ-PGA synthesis,which could also be applied in the production of other metabolites.

关 键 词：Vitreoscilla hemoglobin Expression element Twin-arginine translocation Poly-γ-glutamic acid Bacillus licheniformis 

分 类 号：Q78[生物学—分子生物学]