Extracellular polymeric substances (EPSs) are extracellular macromolecules in bacteria, which function in cell growth and show potential for mechanism study and biosynthesis application. However, the biosynthesis mechanism of EPS is still not clear. We herein chose Bacillus licheniformis CGMCC 2876 as a target strain to investigate the EPS biosynthesis. epsK, a member of eps cluster, the predicted
polysaccharide synthesis cluster, was overexpressed and showed that the overexpression of epsK led to a 26.54% decrease in the production of EPS and resulted in slenderer cell shape. Transcriptome analysis combined with
protein-
protein interactions analysis and
protein modeling revealed that epsK was likely responsible for the synthesis of
teichuronic acid, a substitute cell wall component of teichoic
acid when the strain was suffering
phosphate limitation. Further cell cultivation showed that either
phosphate limitation or the overexpression of
teichuronic acid synthesis genes, tuaB and tuaE could similarly lead to EPS reduction. The enhanced production of
teichuronic acid induced by epsK overexpression triggered the endogenous
phosphate starvation, resulting in the decreased EPS synthesis and biomass, and the enhanced bacterial chemotaxis. This study presents an insight into the mechanism of EPS synthesis and offers the potential in controllable synthesis of target products.