Effect of Nutrient Supplement on Syngas Fermentation With Clostridium Autoethanogenum

The syngas fermentation process is attracting attention as a technology to produce bioethanol from lignocellulosic biomass based syngas or waste gas, but feasibility improvement is required for industrial utilization. The cost of the culture media required for fermentation is a big part of overall fermentation cost, and the yeast extract, which is widely used as nutrient supplement, is a relatively expensive ingredient used to make basal medium for cultivation of acetogenic bacteria. In this study, we investigated the effect of corn steep liquor, malt extract, and vegetable extract as a low cost nutrient substitute for yeast extract on microbial growth and product formation during syngas fermentation. We verified that corn steep liquor, malt extract, and vegetable extract could replace yeast extract in syngas fermentation. Moreover, the use of malt extract and vegetable extract resulted in a significant improvement in ethanol productivity.