USE OF A 3-STAGE LABORATORY MODEL TO DETERMINE THE EFFECTS OF TEMPERATURE ON INDIVIDUAL TROPHIC GROUPS OF METHANOGENIC ASSOCIATIONS ISOLATED FROM ANOXIC LANDFILL

A three-stage continuous culture model system was used to determine th e effects of temperature on methanogenic associations enriched and iso lated from landfill sites. This system allowed spatial segregation of the trophic groups of the associations without disruption of the integ rity of the associations. Three intermediates of anoxic catabolism in landfill sites were selected as the carbon sources for the study: cell obiose, butyrate and valerate. No evidence of thermophilic methanogeni c activity was found in any of the systems. However, some thermophilic sulphate-reducing activity was detected. No inhibition of the cellobi ose-degrading bacteria was evident over the range 20-55 degrees C. The optimum temperature range for methanogenesis was generally 30-35 degr ees C, although there were apparently two methanogenic populations, on e of which maintained methane release rates over the range 20-35 degre es C.