Abstract: Fermentation processes for production of ethanol include supplying a thermophilic microorganism lacking lactate dehydrogenase activity with sugars under conditions in which they metabolise them predominantly by the pyruvate-formate lyase pathway. Importantly, the processes also include supplying sufficient glycerol to convert all of the sugars to ethanol. A further embodiment of the invention includes supplying additional glycerol sufficient to convert the exogenous acetate present in biomass hydrolysates into ethanol. Any type of fermentation system can be used for these processes, but a preferred embodiment includes continuous cultures at high temperatures in which ethanol is removed continuously by vacuum evaporation.

Abstract: Production of ethanol by a process in which a strain of Bacillus stearothermophilus or other thermophilic, facultatively anaerrobic bacterium is selected for the characteristics of fermenting sugars both aerobically and anaerobically and of being active in anaerobic fermentation at 70.degree. C. or above and (i) anaerobic fermentation is carried out with continuing removal of ethanol at 70.degree. C. or above; (ii) the fermentative activity of the bacterium is maintained by withdrawing a proportion of the anaerobic fermentation medium on a continuing basis preferably with removal of ethanol and allowing the bacteria therein to multiply aerobically, using residual sugars or metabolites thereof present in the medium, before being returned to the anaerobic fermentation.