INCREASED ETHANOL-PRODUCTION BY METABOLIC MODULATION OF CELLULOSE FERMENTATION IN CLOSTRIDIUM-THERMOCELLUM

Significant quantitative differences in ethanol yields along with repr ession in acetic acid production were observed in Clostridium thermoce llum strains SS21 and SS22 in the presence of H-2, acetone and sodium azide. Exogenous H-2 addition (1.0 atm) increased the ethanol yields t o 0.40 g/g and ethanol to acetate ratio to 5.75 in strain SS21 but was inhibitory in strain SS22. Addition of acetone reversed the inhibitio n caused by H-2 and increased the ethanol yields and ethanol to acetat e ratio of strain SS22 up to 0.40 g/g and 7.9, respectively. Enhanceme nt in ethanol yields up to 0.40 g/g and 0.41 g/g and ethanol to acetat e ratio up to 3.63 and 8.1 were observed in the presence of 0.2 mM and 0.15 mM concentration of sodium azide by strains SS21 and SS22, respe ctively.