Improving phloroglucinol tolerance and production in Escherichia coli by GroESL overexpression

Microbial Cell Factories

Research

Wei Liu¹  Huizhou Liu¹  Mo Xian¹  Yujin Cao¹  Rubing Zhang² 

[1] CAS Key Laboratory of Bio-Based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 266101, Qingdao, China;CAS Key Laboratory of Bio-Based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 266101, Qingdao, China;University of Chinese Academy of Sciences, 100049, Beijing, China;

关键词: GroESL;    Expression level;    Tolerance;    Escherichia coli;    Phloroglucinol;   

DOI  :  10.1186/s12934-017-0839-x

 received in 2017-08-16, accepted in 2017-12-05,  发布年份 2017

来源: Springer

【 摘 要 】

BackgroundPhloroglucinol is an important chemical which has been successfully produced by engineered Escherichia coli. However, the toxicity of phloroglucinol can enormously inhibit E. coli cell growth and viability, and the productivity is still too low and not economically feasible for industrial applications. Therefore, strain tolerance to toxic metabolites remains a key issue during the production of chemicals using biological processes.ResultsIn the present work, we examined the impact of the native GroESL chaperone system with different overexpression levels on phloroglucinol tolerance and production in E. coli. The groESL gene was cloned into an expression vector, of which expression level was regulated by three different promoters (natural, tac and T7 promoter). Strain tolerance was evaluated employing viable cell counts and phloroglucinol production. In comparison with the control strain, all GroESL overexpressing strains showed good characteristics in cell viability and phloroglucinol synthesis. Strain which overexpressed GroESL under tac promoter was found to show the best tolerance in all of those tested, resulting in a 3.19-fold increase in viable cell numbers compared with control strain of agar-plate culture under the condition of 0.7 g/L phloroglucinol, and a 39.5% increase in phloroglucinol production under fed-batch fermentation. This engineered strain finally accumulated phloroglucinol up to 5.3 g/L in the fed-batch cultivation 10 h after induction, and the productivity was 0.53 g/L/h. To date, the highest phloroglucinol production was achieved in this work compared with the previous reports, which is promising to make the bioprocess feasible from the economical point.ConclusionsThe data show that appropriate expression level of GroESL plays a critical role in improving phloroglucinol tolerance and production in E. coli, and maybe involve in controlling some aspects of the stress response system through upregulation of GroESL. GroESL overexpression is therefore a feasible and efficient approach for improvement of E. coli tolerance.

【 授权许可】

CC BY   
© The Author(s) 2017