Metabolic modeling of bacterial co-culture systems predicts enhanced carbon monoxide-to-butyrate conversion compared to monoculture systems.

We used metabolic modeling to computationally investigate the potential of bacterial coculture system designs for CO conversion to the platform chemical butyrate. By taking advantage of the native capabilities of wild-type strains, we developed two anaerobic coculture designs by combining for CO-to-acetate conversion with bacterial strains that offer high acetate-to-butyrate conversion capabilities: the environmental bacterium the human gut bacterium. When grown in continuous stirred tank reactor on a 70/0/30 CO/H/N gas mixture, the C. autoethanogenum- co-culture was predicted to offer no mprovement in butyrate volumetric productivity compared to an engineered monoculture despite utilizing vinyl acetate as a secondary carbon source for growth enhancement. A coculture consisting of and engineered in silico to eliminate hexanoate synthesis was predicted to enhance both butyrate productivity and titer. The coculture offered similar improvements in butyrate productivity without the need for metabolic engineering when glucose was provided as a secondary carbon source to enhance growth. A bubble column model developed to assess the potential for large-scale butyrate production of the design predicted that a 40/30/30 CO/H/N gas mixture and a 5 m column length would be preferred to enhance growth and counteract CO inhibitory effects on