Production of Butanol From Glycerol Using a Newly Isolated Clostridium Sp

Glycerol is a byproduct from various industrial processes such as biodiesel manufacture and can be converted to other valuable products such as ethanol, butanol, 1,3-propanediol, and 2,3-butanediol by various anaerobic bacteria. In this study, a butanol-producing microorganism utilizing glycerol was isolated from a forest soil sample and butanol production of the isolate was compared with that of Clostridium pasteurianum DSM525 which is a known butanol-producing microorganism from glycerol. By adding acetic and butyric acids into the mineral medium containing glycerol and a forest soil sample, we could enrich butanol-producing bacteria. One of the butanol-producing isolates was identified to belong to C. arbusti according to 16s rDNA analysis. The isolate produced up to 12.5 g/L of butanol when 60 g/L of glycerol was initially added, whereas C. pasteurianum DSM525 produced 10.0 g/L of butanol at most. Unlike C. pasteurianum DSM525, the isolate produced butanol more effectively at low pH (i.e., initial pH 5.3) than at higher pH (i.e., initial pH 5.9 and 6.5). Besides the butanol-producing isolate, a 1,3-propanediol-producing isolate (17.1 g/L of 1,3-propanediol from 30 g/L of glycerol) was also isolated, demonstrating the diversity of glycerol-utilizing bacteria and their potential for industrial application.