Study On Butanol-producing From Steam Blasting Of Populus By Mixed Bacteria

Butanol, as a second generation of biofuels, has been drawn widely attention to all over the world. By means of microbial fermentation, production of butanol from renewable feedstocks has become a focus of this matter. However, low production of butanol is a limit factor to biobutanol producing at present. In order to enhance the yield of butanol production, Breeding high yield strain and optimizating the fermentation technology is absolutely necessary. In this paper, Clostridium Beijerinckii U-57 and Clostridium saccharobutylicum A-18 was acclimatized in butanol breeding respectively, the effect of different additives on production of butanol fermentation and 3-L fermentor enlarge test were discussed. The main results were as follows:(1) The high concentration butanol tolerance of C. Beijerinckii U-57 and C. Saccharobutylicum A-18 was 14g/L and 16g/L. By butanol screening and subculturing, C. Beijerinckii B5-15 and C. saccharobutylicum B7-36 were obtained. The production of butanol by mixed bacteria fermentation was higher than single one. After detoxification, the yield from populus steam blasting slag of butanol and total solvent were 5.44g/L and 8.45g/L, which were improved 5.22% and 10.31% than undetoxfication.(2) In order to discuss the effect of different additives on butanol production, the results of orthogonal experiment by using SPSS program were as follow:4g/L CaCO3 had a significant effect on butanol production. Under this circumstance, the yield of butanol and total solvent were 6.83g/L and 10.18g/L, respectively.0.6g/L tween-80, 0.6% SDS and 0.8g/L butyric acid had no significant influence on ABE (acetone-butanol-ethanol) fermentation, and the influence went down in turns.(3) The mixed bacteria composition was an influence factor in fermentation of populus steam-blasting slag. The best proportion of C. Beijerinckii U-57 and C. Saccharobutylicum A-18 was 1:1. Temperature, pH and inoculation quantities were also important. Through single factor and orthogonal experiments, the best conditions of butanol fermentation were:fermetation temperature 39℃, pH 6.1 and inoculums volume 6%. After optimizing the fermentation conditions of SSF (Simultaneous saccharification and fermentation), the yield of butanol and total solvent produced by mixed bacteria were 7.12g/L and 11.67g/L, which was lower than 7.34g/L and 12.19 g/L in SHF (Separate hydrolysis and fermentation). Though the yeild of SSF was not high, it could enhance the production efficiency tremendously, which provided some references for intensive study.