Isolation of Cellulolytic Clostridia and their Performance for One-Step Butanol Production from Sugarcane Bagasse

The objective of this study was to screen cellulolytic clostridia from soil, compost, cow dung, buffalo dung and elephant dung in Thailand for one-step butanol production from cellulosic materials. Cellulolytic activity and butanol tolerance were used as criteria to isolate cellulolytic and butanol-tolerant bacteria using mineral salt medium supplemented with 20 g/L Avicel and 5 g/L butanol. It was found that two isolates from each source were obtained according to the isolation criteria. These isolates were gram positive, rod-shaped, endospore forming and sulfite-reducing, which corresponded to the Clostridia class. Then, a one-step butanol production from sugarcane bagasse by these isolates was investigated. Butanol production in a 5-L fermenter showed that the isolate E11-KKU from elephant dung exhibited the highest potential and achieved the highest butanol concentration of 3.17 g/L. Phylogenetic analysis of the 16S rDNA sequence showed that the isolate E11-KKU was identified as Clostridium beijerinckii with 99.99% identity.