Abstract
Mixed culture of Methylomonas flagellata, a methane-utilizing bacterium, and Alcaligenes eutrophus, a hydrogen-utilizing bacterium, was attempted in order to use the carbon dioxide produced from methane by the former bacterium as the carbon source for the autotrophic growth of the latter. In mixed culture with methane and hydrogen as the carbon and energy sources, carbon dioxide produced by M. flagellata was utilized almost completely by A. eutro-phus, and recycling of gaseous substrates was possible in a closed cultivation system. However, growth of the mixed culture was poor compared to growth of M. flagellata and A. eutrophus in pure culture. During growth of the mixed culture, a predominance of A. eutrophus and decay of M. flagellata were observed. A. eutrophus seemed to inhibit the growth of M. flagellata by its preferential uptake of carbon dioxide and by production of a growth inhibitor.
