METHANOTROPH AND METHANOGEN COUPLING IN GRANULAR BIOFILM UNDER O-2-LIMITED CONDITIONS

The co-culture between Methylosinus sporium, a strictly aerobic methan otroph, and strictly anaerobic methanogens was studied in 5 L aerobic/ anaerobic coupled granular sludge reactors under O-2-limited condition s. The methanogenic bacteria maintained very good metabolic activities and were able to produce sufficient methane which serviced as substra te for methanotrophic growth. Although other strictly aerobic populati on proliferated by two orders of magnitude after the granular sludge h ad been operated under O-2-limited conditions for one month, only a li mited amount of the added methanotroph remained in the sludge. This re sult may indicate that M. sporium lacks sufficient O-2 affinity to com pete with facultative bacteria for the dissolved O-2 for their growth.