Escherichia coli genome-scale metabolic gene knockout of lactate dehydrogenase (ldhA), increases succinate production from glycerol.

Genome-scale metabolic model (GEM) of Escherichia coli has been published with applications in predicting metabolic engineering capabilities on different carbon sources and directing biological discovery. The use of glycerol as an alternative carbon source is economically viable in bio-refinery. The use of GEM for predicting metabolic gene deletion of lactate dehydrogenase (ldhA) for increasing succinate production in E. coli from glycerol carbon source remained largely unexplored. Here I hypothesized that metabolic gene knockout of ldhA in E. coli from glycerol could increase succinate production. A proof-of-principle strainwas constructed and designated as E. coli BMS5 (ΔldhA), by predicting increased succinate production in E. coli GEM and confirmed the predicted outcomesusing wet cell experiments. The mutant GEM (ΔldhA) predicted 11% increase in succinate production from glycerol compared to its wild-type model (iAF1260) and the E. coli BMS5 (ΔldhA) showed 1.05 g/l and its corresponding wild-type produced 0.05 g/l (23 fold increase). The proof-of-principle strain constructed in this study confirmed the aforementioned hypothesis, and further elucidate the fact that E. coli GEM can prospectively and effectively predict metabolic engineering interventionsusingglycerol as substrateand could serve as platform for new strain designstrategies and biological discovery.