Engineering of a newly isolated Bacillus tequilensis BL01 for poly-γ-glutamic acid production from citric acid

Microbial Cell Factories

Research

Xiaoping Fu¹  Dexin Wang¹  Wenqin Bai¹  Jiaqi Gao²  Dasen Zhou³ 

[1] CAS Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 300308, Tianjin, China;National Center of Technology Innovation for Synthetic Biology, 300308, Tianjin, China;CAS Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 300308, Tianjin, China;National Center of Technology Innovation for Synthetic Biology, 300308, Tianjin, China;University of Chinese Academy of Sciences, 19A Yuquan Road, Shijingshan District, 100049, Beijing, China;College of Biotechnology, Tianjin University of Science and Technology, 300457, Tianjin, China;

关键词: Poly-γ-glutamic acid;    Bacillus tequilensis;    Metabolic engineering;    Gene knockout;   

DOI  :  10.1186/s12934-022-01994-z

 received in 2022-10-20, accepted in 2022-12-14,  发布年份 2022

来源: Springer

【 摘 要 】

BackgroundPoly γ-glutamic acid (γ-PGA) is a promising biopolymer for various applications. For glutamic acid-independent strains, the titer of γ-PGA is too low to meet the industrial demand. In this study, we isolated a novel γ-PGA-producing strain, Bacillus tequilensis BL01, and multiple genetic engineering strategies were implemented to improve γ-PGA production.ResultsFirst, the one-factor-at-a-time method was used to investigate the influence of carbon and nitrogen sources and temperature on γ-PGA production. The optimal sources of carbon and nitrogen were sucrose and (NH4)2SO4 at 37 °C, respectively. Second, the sucA, gudB, pgdS, and ggt genes were knocked out simultaneously, which increased the titer of γ-PGA by 1.75 times. Then, the titer of γ-PGA increased to 18.0 ± 0.3 g/L by co-overexpression of the citZ and pyk genes in the mutant strain. Furthermore, the γ-PGA titer reached 25.3 ± 0.8 g/L with a productivity of 0.84 g/L/h and a yield of 1.50 g of γ-PGA/g of citric acid in fed-batch fermentation. It should be noted that this study enables the synthesis of low (1.84 × 105 Da) and high (2.06 × 106 Da) molecular weight of γ-PGA by BL01 and the engineering strain.ConclusionThe application of recently published strategies to successfully improve γ-PGA production for the new strain B. tequilensis BL01 is reported. The titer of γ-PGA increased 2.17-fold and 1.32-fold compared with that of the wild type strain in the flask and 5 L fermenter. The strain shows excellent promise as a γ-PGA producer compared with previous studies. Meanwhile, different molecular weights of γ-PGA were obtained, enhancing the scope of application in industry.

【 授权许可】

CC BY   
© The Author(s) 2022

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