Effect of temperature and pH on ethanol production by a Blastomyces species isolated from the intestine of oil palm weevil (Rhynchophorus palmarum, coleoptera)

Abstract

The effects of pH (4.5, 5.0, 5.5, 6.0, 6.5 and 7.0), temperature (20, 25, 30, 35, 40 and 45°C) and combinations of the two (pH 4.5, 20°C; pH 5.0, 25°C; pH 5.5, 30°C; pH 6.0, 35°C; pH 6.5, 40°C; pH 7.0, 45°C) on ethanol production by a putative Blastomyces species isolated from the intestine of oil palm weevil larva were studied. Peptone water was used as the growth medium and granulated sugar (sucrose) was used as the fermentation substrate. Ethanol contents were determined gravimetrically and the percentage of ethanol was determined as volume estimated from an alcoholometry table. Results show that the highest amount of ethanol (10.50%) was produced at a temperature of 35°C and the lowest (3.15%), at 20°C. Similarly, the highest amount (4.95%) was produced at a pH of 5.0 while the lowest (3.03%) was at pH 7.0. When pH and temperature were taken together, the highest amount of ethanol (6.0%) was produced at temperature 30°C and pH 5.5. Appropriate adjustments in pH and temperature of the fermenting medium are, therefore, necessary for maximum ethanol production by the organism.