초록
H<SUB>2</SUB> supply constitutes the bottleneck for the biogenic recycling of CO<SUB>2</SUB> to CH<SUB>4</SUB> via the reduction pathway with H<SUB>2</SUB>. Past studies have reported that yeast extract has a significant effect on H<SUB>2</SUB> formation from various types of organic matter. In order to elucidate whether or not less expensive protein-rich matter like protein powder from soybean can be used as substitute for yeast extract, a comparative assessment of biogenic conversion of CO<SUB>2</SUB> to CH<SUB>4</SUB> with H<SUB>2</SUB> supply from the fermentation of yeast extract, protein powder from soybean, and glucose was done using a mixture culture of H<SUB>2</SUB>-forming fermentative and H<SUB>2</SUB>-using methanogenic microbes. Batch experiment results showed that under H<SUB>2</SUB> limitation conditions, larger amounts of H<SUB>2</SUB> is supplied at the expenses of less CO<SUB>2</SUB> production with yeast extract and protein powder from soybean than with glucose. Protein powder from soybean has been found to have similar stimulating effect on H<SUB>2</SUB> formation to yeast extract. The biogenic conversion of CO<SUB>2</SUB> to CH<SUB>4</SUB> with protein powder from soybean was reflected by a net reduction of CO<SUB>2</SUB> levels. For the first time, it is shown that soybean protein is a potential candidate to stimulate the biogenic recycling of CO<SUB>2</SUB> to CH<SUB>4</SUB> in geological storage sites of CO<SUB>2</SUB>.