Enhanced Cellulose Fermentation by an Asporogenous and Ethanol-Tolerant Mutant of Clostridium thermocellum.

A mutant of Clostridium thermocellum isolated after UV mutagenesis and selection for resistance to fluoropyruvate was found to be asporogenous and ethanol tolerant. The mutant was also an ethanol hyperproducer, able to ferment 63 g of cellulose into 14.5 g of ethanol per liter of medium. The ratio of ethanol to total organic acids produced by the mutant was increased, and H(2) production was decreased. Culture conditions were optimized for ethanol production by the new strain.