초록
<P><B>Abstract</B></P> <P> <I>Bacillus subtilis</I> is widely used as cell factories for the production of important industrial biochemicals. Although many studies have demonstrated the effects of organic acidic byproducts, such as acetate, on microbial fermentation, little is known about the effects of blocking the neutral byproduct overflow, such as acetoin, on bioproduction. In this study, we focused on the influences of modulating overflow metabolism on the production of N-acetyl-<SMALL>D</SMALL>-glucosamine (GlcNAc) in engineered <I>B. subtilis</I>. We found that acetoin overflow competes with GlcNAc production, and blocking acetoin overflow increased GlcNAc titer and yield by 1.38- and 1.39-fold, reaching 48.9 g/L and 0.32 g GlcNAc/g glucose, respectively. Further blocking acetate overflow inhibited cell growth and GlcNAc production may be induced by inhibiting glucose uptake. Taken together, our results show that blocking acetoin overflow is a promising strategy for enhancing GlcNAc production. The strategies developed in this work may be useful for engineering strains of <I>B. subtilis</I> for producing other important biochemicals.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Competitive overflow of acetoin was blocked to promote GlcNAc production. </LI> <LI> Addition of calcium carbonate as a neutralizing agent minimized acetate toxicity. </LI> <LI> The GlcNAc titer in 3-L bioreactor increased by 38% by metabolic engineering of overflow metabolism. </LI> </UL> </P>