Analysis Of Biosynthesis 2,3-Butanediol Production With Klebsiella Pneumoniae

2,3-butanediol was an important chemical because it has a large number of industrial applications. Comparing with the chemical process, the biological process was safe, environmental friendly, mild reaction condition and could use renewable resources. So it has been paid more and more attentions. Nowadays, many research efforts have focused on using low price substrates lignocellulosic hydrolysate to produce the 2,3-butanediol. However, both the 2,3-butanediol concentration and the productivity were lower than those of glucose. This paper investigated the screening of producing strains, the sugars fermented and operating conditions applied on 2,3-butanediol fermentation by Klebsiella pneumoniae with synthetic medium of rice straw hydrolysate.In order to improve strain to produce 2,3-butanediol with high yield, UV mutagenesis with acid-producing and product tolerance capability was established to select positive mutant bacteria. A strain named Klebsiella pneumoniae UV-86 (K.pneumoniae UV-86) with the highest 2,3-butanediol production capability and heritage stability was chosen as the target strain for the following investigations. The yield of 2,3-butanediol by K.pneumoniae UV-86 was 0.438g/g, which was 1.22 times to that of the original strain. The specific activity of 2, 3-butanediol dehydrogenase was increased by 38.6%. The results demonstrated the effective and efficient high throughput screening technique.The sugars fementated, temperature and pH were investigated for the bio-production of 2, 3-butanediol. It was found that the order of the preferential sugar utilization was glucose>xylose. The optimal temperature and pH for bacterial fermentation with glucose and xylose were 30℃and 6.0, respectively. The cell growth was improved by adding acetate and the maximum 2,3-butanediol concentration was obtained by acetate adding concentration 1g/L.In order to investigate the influence of dissolved oxygen concentration on 2, 3-butanediol bioproduction process, the cofermentation of glucose and xylose was investigated. It was found that high oxygen supply favoured cell mass formation. The influence of oxygen on glucose consumption was not significant. But it had a significant impact on xylose consumption and the average specific xylose consumption rate was improved with the oxygen supply. The micro-aerobic condition favoured formation of 2, 3-butanediol. The maximum 2,3-butanediol concentration 30.1g/L and productivity 0.485g/ (L h) were both obtained at 1.5vvm. The accumulation of acetate was enhanced during the xylose metabolism process. According to these results, the oxygen supply control strategy was proposed.