Deleting chaperone-usher fimbriae operons to improve L-threonine production in Escherichia coli
Dengke Gong, Jun Qiao, Hedan Li, Ying Li, Danyang Huang, Zhen Wang, Xiaoqing Hu, Xiaoyuan Wang
Systems Microbiology and Biomanufacturing ›› 2023, Vol. 4 ›› Issue (1) : 175-187.
Deleting chaperone-usher fimbriae operons to improve L-threonine production in Escherichia coli
Escherichia coli contains 12 chaperone-usher operons, including 64 genes, used for biosynthesis and assembly of various fimbriae which consume a lot of energy and material. In this study, each of the 12 operons was deleted in an L-threonine-producing E. coli strain TWF001, and the resulting 12 deletion mutants produced more L-threonine than TWF001 after 16 or 24 h cultivation. Therefore, the 12 chaperone-usher operons were deleted in different combinations, resulting in 11 strain mutants which lack at least 2 operons. The cell growth and L-threonine production of these 11 mutants were determined. Among these 11 mutants, TWK021 in which 10 chaperone-usher operons were deleted, showed the highest L-threonine production. TWK021 produced 15.75 g L-threonine from 40 g glucose after 36 h cultivation. The conversion rate of glucose to L-threonine reached 0.394 g/g in TWK021, which is 32.2% higher than the control strain TWF001. These results suggest that the fimbria lacking E. coli TWK021 is a good host for efficient production of L-threonine.
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