Promoting cell growth for bio-chemicals production via boosting the synthesis of L/D-alanine and D-alanyl-D-alanine in Bacillus licheniformis

AbstractMetabolic engineering is a substantial approach for escalating the production of biochemical products. Cell biomass is lowered by system constraints and toxication carried on by the aggregation of metabolites that serve as inhibitors of product synthesis. In order to increase the production of biochemical products, it is important to trace the relationship between alanine metabolism and biomass. According to our investigation, the appropriate concentration of additional L/D-alanine (0.1  g/L) raised the cell biomass (OD600) inBacillus licheniformis in contrast to the control strain. Remarkably, it was also determined that high levels of intracellular L/D-alanine and D-alanyl-D-alanine were induced by the overexpression of theald,dal, andddl genes to accelerate cell proliferation. Our findings clearly revealed that 0.2  g/L of L-alanine and D-alanine substantially elevated the titer of poly-γ-glutamic acid (γ-PGA) by 14.89% and 6.19%, correspondingly. And the levels of γ-PGA titer were hastened by the overexpression of theald,dal, andddl genes by 19.72%, 15.91%, and 16.64%, respectively. Furthermore, overexpression ofald,dal, andddl genes decreased the by-products (acetoin, 2,3-butanediol, acetic acid and lactic acid) formation by about 14.10%, 8.77%, and 8.84% for augmenting the γ-PGA production. Our results also demonstrated that overexpression ofald gene amplified the production of lichenysin, pulcherrimin and nattokinase by about 18.71%, 19.82% and 21.49%, re...
Source: World Journal of Microbiology and Biotechnology - Category: Microbiology Source Type: research