Clostridium beijerinckii is an anaerobic bacterium well known for the fermentative production of solvents including acetone, butanol and ethanol which can be developed into biofuels.  To investigate the mechanism of genetic regulation in clostridial solventogenesis, gene expression over the course of batch fermentation is studied by DNA microarray analysis using the wild-type strain and a hyper-butanol producing mutant strain BA101.  The results reveal significant differences between the mutant BA101 and the wild-type in the transcription of diverse genes in multiple functional classes which are necessary for solventogenesis, sporulation, motility and sugar transport.  Taken together, these genetic variations appear to collectively contribute to improved butanol formation in the mutant.  This study points to the potential of further genetic modification in clostridia to achieve higher efficiency in sustainable biofuel production.