Construction of a fimbriae absent < em > Escherichia coli < /em > by deleting 64 genes and its application for efficient production of poly-3-hydroxybutyrate and L-threonine

In this study, each of the 12 operons was deleted in E. coli MG1655, and the resulting 12 deletion mutants all grew better than the wild type, especially in the nutrient-deficient M9 medium. When the plasmid pBHR68 containing the key genes for polyhydroxyalkanoate production was introduced into these 12 mutants, each mutant synthesized more polyhydroxyalkanoate than the wild type control. These results indicate that the fimbriae removal in E. coli benefits cell growth and polyhydroxyalkanoate production. Therefore, all the 12 chaperone-usher operons including 64 genes were deleted in MG1655, resulting the fimbriae absent strain WQM026. WQM026 grew better than MG1655, and no fimbriae structures were observed on the surface of WQM026 cells. Transcriptomic analysis showed that in WQM026 cells the genes related to glucose consumption, glycolysis, flagellar synthesis, and biosynthetic pathways of some key amino acids were up-regulated, while the TCA cycle related genes were down-regulated. When pBHR68 was introduced into WQM026, huge amounts of poly-3-hydroxybutyrate were produced; when the plasmid pFW01-thrA*BC-rhtC containing the key genes for L-threonine biosynthesis and transport was transferred into WQM026, more L-threonine was synthesized than the control. These results suggest that this fimbriae absent E. coli WQM026 is a good host for efficient production of polyhydroxyalkanoate and L-threonine, and has the potential to be developed into a valuable chassis microorganism.IM...
Source: Applied and Environmental Microbiology - Category: Microbiology Authors: Source Type: research