Regulating Cardiolipin Biosynthesis for Efficient Production of Colanic Acid in Escherichia coli

Colanic acid has broad application prospects in the food and healthcare market due to its excellent physical properties and biological activities. In this study, we discovered that colonic acid production in Escherichia coli could be enhanced by regulating cardiolipin biosynthesis. Single deletion of clsA, clsB, or clsC related to cardiolipin biosynthesis in E. coli MG1655 only slightly increased colonic acid production, but double or triple deletion of these three genes in E. coli MG1655 increased colonic acid production up to 2.48-fold. Previously, we have discovered that truncating lipopolysaccharide by deletion of the waaLUZYROBSPGQ gene cluster and enhancing RcsA by deletion of genes lon and hns can increase colonic acid production in E. coli. Therefore, these genes together with clsA, clsB, or/and clsC were deleted in E. coli, and all the resulting mutants showed increased colonic acid production. The best colonic acid production was observed in the mutant WWM16, which is 126-fold higher than in the control MG1655. To further improve colonic acid production, the genes rcsA and rcsD were overexpressed in WWM16, and the resulting recombinant E. coli WWM16/pWADT could produce 44.9 g/L colonic acid, which is the highest titer reported to date.