Autotrophic (C1-gas) versus heterotrophic (fructose) accumulation of acetic acid and ethanol in Clostridium aceticum

The influence of the carbon source on the metabolism and growth of Clostridium aceticum was investigated, supplying either CO or fructose as sole carbon source. The acid and solvent production patterns were determined under either autotrophic or heterotrophic conditions, elucidating the effect of pH on the substrate's bioconversion pattern. The highest maximum specific growth rate was observed with CO, under the organism's optimal growth conditions, reaching 0.052 h-1 and an acetic acid concentration of 18 g.L- 1. The production of 4.4 g.L- 1 ethanol was also possible, after medium acidification, during CO bioconversion. Conversely, formic acid inhibition was observed during fructose fermentation under optimal growth conditions. In the latter experiments, it was not possible to stimulate solvent production when growing C. aceticum on fructose, despite applying the same medium acidification strategy as with CO, showing the selective effect of the carbon source (autotrophic vs heterotrophic) on the metabolic pattern and solventogenesis.

Automated summary

The influence of carbon source, CO or fructose, on the metabolism and growth of Clostridium aceticum was investigated. Optimal growth conditions with CO showed the highest specific growth rate and acetic acid production, while fructose fermentation resulted in formic acid inhibition. The carbon source had a selective effect on metabolic patterns and solventogenesis of C. aceticum.