High yield bio-butanol production by solvent-producing bacterial microflora

摘要

Highly efficient butanol-producing bacterial microflora were isolated from hydrogen-producing sludge of a sewage treatment plant. Based on denaturing gradient gel electrophoresis (DGGE) analysis and 16s rDNA comparison, four strains from the butanol-producing microflora were identified as Clostridium saccharoperbutylacetonicum, Clostridium butylicum, Clostridium beijernckii, and Clostridium acetobutylicum. The effects of glucose, FeSO _4·7H _2O and yeast extract concentrations on the butanol production by the mixture culture were investigated on batch mode. The medium composition for bio-butanol production was optimized using the Box-Behnken design and response surface methodology (RSM). The maximum butanol production rate (0.25±0.02g/L-h) and concentration (12.4g/L) were obtained under the condition of glucose concentration, 60g/L; FeSO _4·7H _2O, 0.516g/L; yeast extract concentration, 5.13g/L. Addition of 6.0g/L butyric acid significantly increased the butanol titer to 17.51±0.49g/L. Pressurized fermentation strategy (employed with a 5L fermentor) further enhanced the butanol concentration to 21.35g/L, along with a maximum butanol rate of 1.25g/L-h.