Selective methanol or formate production during continuous CO2 fermentation by the acetogen biocatalysts engineered via integration of synthetic pathways using Tn7-tool

Methanol-resistant mutant acetogen Clostridium sp. MT1424 originally producing only 365 mM acetate from CO2/CO was engineered to eliminate acetate production and spore formation using Cre-lox66/lox71-system to power subsequent methanol production via expressing synthetic methanol dehydrogenase, formaldehyde dehydrogenase and formate dehydrogenase, three copies of each, assembled in cluster and integrated to chromosome using Tn7-based approach. Production of 2.2 M methanol was steady (p < 0.005) in single step fermentations of 20 % CO2 + 80 % H-2 blend (v/v) 25 day runs each in five independent repeats. If the integrated cluster comprised only three copies of formate dehydrogenase the respective recombinants produced 95 mM formate (p < 0.005) under the same conditions. For commercialization, the suggested source of inorganic carbon would be CO2 waste of IGCC power plant. Hydrogen may be produced in situ via powered by solar panels electrolysis.