The biosynthesis of the enterobacterial common antigen and flagella in Escherichia coli consumes lots of substrates and energy. In this study, 12 genes responsible for the biosynthesis of the enterobacterial common antigen were deleted in E. coli MG1655, resulting in WQM021. WQM021 grew better than MG1655 in both rich LB medium and minimum M9 medium. Compared with MG1655, WQM021 showed higher membrane permeability and higher production efficiency for recombinant proteins, polyhydroxyalkanoate, and l-threonine. Transcriptome analysis revealed that genes relevant to glucose consumption, glycolysis, and flagellar synthesis were significantly upregulated in WQM021. Therefore, 50 genes responsible for flagellar biosynthesis were further deleted in WQM021, resulting in WQM022. WQM022 grew better and could synthesize more polyhydroxyalkanoate and l-threonine than WQM021. The results demonstrate that the productivity of E. coli can be efficiently improved when the enterobacterial common antigen and flagella are eliminated. This strategy has guiding significance in the optimization of other industrial products and microorganisms.
Keywords: Escherichia coli; PHB; enterobacterial common antigen; flagella; l-threonine; polyhydroxyalkanoate; transcriptome.