Effect of temperature on growth and activity of a methanogenic culture utilising acetate

Studies with a methanogenic culture enriched for use of acetic acid showed that this culture had an optimum growth temperature of 35 degrees C, with only small differences for other temperatures between 30 and 40 degrees C. The optimum temperature was the same when determined on the basis of biomass production rate during the exponential (log) phase of growth (0.08-0.09 day-1, at 35 degrees C), amount of biomass present at the end of the log phase (100 mg/l), activity of the biomass (rate of conversion in millimoles per day per milligram (dry wt.) biomass present, 0.08 at end of log phase), or biomass yield (mg (dry wt.) biomass produced per millimole acetic acid converted, 1.0-1.1). Temperatures outside the range 30 to 40 degrees C caused marked reductions in the above parameters. The maximum temperature for growth was 42-44 degrees C; the minimum, below 15 degrees C, the lowest temperature studied. Acetic acid conversion to methane was 0.8-1.0 mol/mol, and was independent of temperature.