Under anaerobic conditions at temperatures below 30°C, the attack on bagasse fiber by cellulolytic microorganisms is insignificant and only fermentation of sugars by yeasts occurs. The anaerobic fermentation of the sugars and water solubles at low temperatures by the yeasts produces primarily, alcohol, carbon dioxide and heat; though some organic acids are produced as well. As the temperature rises above 30°C due to the anaerobic fermentation of the sugars, the activity of the yeasts declines and the activity of thermophylic cellulolytic microorganisms increases but still remains relatively insignificant up to about 40°C.