EMS-Induced Mutagenesis of Clostridium carboxidivorans for Increased Atmospheric CO2 Reduction Efficiency and Solvent Production

摘要

(P7) is one of the most important solvent-producing bacteria capable of fermenting syngas (CO, CO , and H ) to produce chemical commodities when grown as an autotroph. This study aimed to develop ethyl methanesulfonate (EMS)-induced P7 mutants that were capable of growing in the presence of CO as a unique source of carbon with increased solvent formation and atmospheric CO reduction to limit global warming. Phenotypic analysis including growth and end product characterization of the P7 wild type (WT) demonstrated that this strain grew better at 25 °C than 37 °C when CO served as the only source of carbon. In the current study, 55 mutagenized mutants were developed by using 100 mM and 120 mM EMS. Interestingly, using a forward genetic approach, three out of the 55 mutants showed a significant increase in ethanol, butyrate, and butanol production. The three mutants presented on average a 4.68-fold increase in concentrations of ethanol when compared to the P7-WT. Butyric acid production from 3 mutants contained an average of a 3.85 fold increase over the levels observed in the P7-WT cultures under the same conditions (CO only). In addition, one mutant presented butanol production (0.23 ± 0.02 g/L), which was absent from the P7-WT under CO conditions. Most of the mutants showed stability of the obtained end product traits after three transfers. Most importantly, the amount of reduced atmospheric CO increased up to 8.72 times (0.21 g/Abs) for ethanol production and up to 8.73 times higher (0.16 g/Abs) for butyrate than the levels contained in the P7-WT. Additionally, to produce butanol, the mutant presented 0.082 g/Abs of CO reduction. This study demonstrated the feasibility and effectiveness of employing EMS mutagenesis in generating solvent-producing anaerobic bacteria mutants with improved and novel product formation and increased atmospheric CO reduction efficiency.