Butanol production by Clostridium pasteurianum NRRL B-598 in continuous culture compared to batch and fed-batch systems

Abstract Butanol production by acetone–butanol–ethanol (ABE) fermentation is usually associated with Clostridium acetobutylicum . In this report, ABE fermentation using the little known, oxygen tolerant solventogenic strain, Clostridium pasteurianum NRRL B-598, in packed-bed continuous cultures is described and compared with suspended cells in continuous, batch and fed-batch processes. While the highest butanol and total ABE concentrations (8.3 and 12.3 g/L respectively), were obtained in fed-batch fermentation, the highest solvent yield and productivity (32% and 0.73 g/L/h), were achieved in packed-bed continuous fermentation at a dilution rate of 0.12 1/h. In these processes, the strain showed exceptional stability, as demonstrated not only by low deviations in process parameters in batch and fed-batch experiments but also long-term stability (over 700 h, or more than 35 bioreactor residence times) in continuous fermentations.