High efficient ethanol and VFA production from gas fermentation: Effect of acetate, gas and inoculum microbial composition
In bioindustry, syngas fermentation is a promising technology for biofuel production without the use of
plant biomass as sugar-based feedstock. The aim of this study was to identify optimal conditions for high
efficient ethanol and volatile fatty acids (VFA) production from synthetic gas fermentation. Therefore, the
effect of different gases (pure CO, H2, and a synthetic syngas mixture), media (acetate medium and
acetate-free medium), and biocatalyst (pure and mixed culture) were studied. Acetate was the most
dominant product independent on inoculum type. The maximum concentration of volatile fatty acids
and ethanol was achieved by the pure culture (Clostridium ragsdalei). Depending on the headspace gas
composition, VFA concentrations were up to 300% higher after fermentation with Clostridium ragsdalei
compared to fermentation with mixed culture. The preferred gas composition with respect to highest
VFA concentration was pure CO (100%) regardless of microbial composition of the inoculum and media
composition. The addition of acetate had a negative impact on the VFA formation which was depending
.