ENHANCED BUTANOL PRODUCTION BY CLOSTRIDIUM-BEIJERINCKII-BA101 GROWN IN SEMIDEFINED P2-MEDIUM CONTAINING 6-PERCENT MALTODEXTRIN OR GLUCOSE

Dramatically elevated levels of butanol and acetone resulted in higher butanol and total solvent yields for hyperamylolytic Clostridium beij erinckii BA101 relative to the NCIMB 8052 parent strain grown in semid efined P2 medium containing either 6% glucose or STAR-DRT 5 maltodextr in. C. beijerinckii BA101 consistently produced on the order of 19 g o f butanol per liter in 20-liter batch fermentations. This represents a greater than 100% increase in butanol concentration by the BA101 stra in compared to the parent NCIMB 8052 strain. The kinetics of butanol p roduction over time also indicate a more rapid rate of butanol product ion by BA101 in semidefined P2 medium containing glucose or maltodextr in. The lower levels of butyric and acetic acids produced over the cou rse of the fermentation carried out by BA101 are consistent with an en hanced capacity for uptake and recycling of these acids. C. beijerinck ii BA101 appears to more completely utilize carbohydrate compared to t he 8052 strain. Carbon balance following fermentation by C. beijerinck ii 8052 and BA101 indicates that sufficient carbon is available for th e twofold increase in butanol concentration observed during BA101 ferm entations. C. beijerinckii BA101 also has superior solvent production capacity during continuous culture fermentation in P2 medium containin g 6% glucose. Volumetric solvent yields of 0.78 and 1.74 g/liter/h for BA101 and 0.34 and 1.17 g/liter/h for NCIMB 8052 were obtained at dil ution rates of 0.05 and 0.20 h(-1), respectively. No drift towards aci d synthesis (strain degeneration) was observed for up to 200 h (d = 0. 05 h(-1)) and 100 h (d = 0.20 h(-1)).