(623m) Engineering the Robustness of Industrial Microbes Through Introducing Metabolic Redundancy

Robustness refers to the ability to maintain phenotypic stability when facing diverse perturbations. It has been shown that microbial robustness coping with environmental stresses can be improved through overexpression of chaperone proteins. We show that the stress resistance of lactic acid bacteria (Lactococcus lactis and Lactobacillus sanfranciscensis) can be improved by introducing glutathione (GSH), a tripeptide which cannot be produced by these bacteria. We further show that introducing the GSH biosynthetic pathway into Clostridium acidobutylicum can improve the aero- and solvent-resistance of the host. Lacking the native GSH biosynthetic ability in these Gram-positive bacteria suggests that GSH is not primarily needed for their physiology, thus can be considered as redundant for their metabolism. Our results demonstrated that introducing this metabolic redundancy can improve the robustness of the host. Therefore, strategies of exploiting and engineering the functional metabolic redundancy may help microbes to better adapt themselves to the industrial environments.