Researches On The Technology Of Butanol Fermentation From Fiber And Screening Of Butanol Biofuel Producing Strains

The acetone-butanol fermentation was ranked second only to ethanol fermentation in its scale of production,and was one of the largest biotechnological processes ever known. However, since the 1950’s industrial ABE fermentation has declined continuously. Currently ABE fermentation is becoming more and more attractive for butanol has excellent fuel performance due to the exhaustion of energy sources.However, being low in solvent concentration,low in production efficiency and high in raw material cost makes acetone-butanol fermentation uneconomical. Therefore,study on optimization of fermentation technology using the lignocellulose as raw material and selecting and breeding of high yield strain is absolutely theoretical significance and applicable value.With butanol and total solvent production as the main index,fermentation conditions using corn as raw material were optimized for Clostridium acetobutylicum 8016.The results indicated that the optimal fermentation conditions were as follows: seed age 24h, inoculum volume 10%(v/v),100mL medium in 100mL flask, initial pH 6,the concentration of yeast extract 0.01%(w/v),C/N(nitrogen source is bran) ratio 10:1,fermentation time 60h.At this conditions, total solvent yield was 6.23g/L, butanol yield reached 4.08g/L and was 65.5% for the total solvent yield.Screen of high solvent producing strains were also studied and strain C2 with high-ratio butanol producing character was obtained.C2 were identified according to the morphology and 16S rDNA sequence, and was identified as gram positive bacillus sp. strain. C2 was most related to B. vallismortis DSM111031T, B. atrophaeus JCM9070T and B. mojavensis IFO1571T and 16S rDNA similarity between them was 99%.C2 and Clostridium acetobutylicum 8016 both have extensive range of sugar utilization.At the same condition,solvent yield of C2 was 17.17 g/L and 4% higher than 8016 when fermented corn liquor and butanol ratio was more than 66%.Solvent yield of C2 was 3.64 g/L and 12.29% lower than 8016 when fermented corn fibre saccharified liquid, while butanol ratio was more than 72%.It was shown that the ability of utilizing corn fibre saccharified liquid of C2 should be improved.