2001 Volume 16 Issue 4 Pages 222-226
In a design utilizing a sterilized soil-mediated co-culture of methanogenic archaeon and methanotrophic bacterium, the activities of both the methanogen and methanotroph were examined. It was confirmed that CH4 was produced by the methanogen after methanotrophic inoculation and suggested that this CH4 was oxidized by the methanotroph as the concentration of O2 increased, although emission of CH4 itself was indirect proof of CH4-oxidizing activity. On the other hand, in the control treatment, methanogenic inoculation without methanotrophic inoculation at different levels of O2, CH4 was not emitted (there was no activity to produce CH4). These results suggest a symbiotic relation in this co-culture system, because the methanogen provided CH4 to the methanotroph, while inoculation of the methanotroph was necessary for subsequent production of CH4 by the methanogen. The development of co-culture systems is essential for understanding the close relationship and interaction between methanogens and the methanotrophs in natural and agricultural environments.