合成气发酵生产乙醇菌株的筛选

Screening of a Microbial Strain Capable of Producing Ethanol from Syngas Fermentation

[目的]从动物粪便样品中分离能利用合成气生产乙醇的菌株，并对其进行鉴定及初步发酵实验，为工业利用合成气生产乙醇奠定理论基础。[方法]利用富集驯化培养技术，以合成气为唯一碳源，分离筛选合成气利用菌，通过形态观察、生理生化实验及16S rRNA 序列分析鉴定菌株，并利用菌株进行初步发酵实验。[结果]分离到1株可以发酵合成气生产乙醇的菌株，分子鉴定结果表明，该菌株为 Clostridium ljungdahlii 。生理生化分析结果显示：该菌是严格厌氧型革兰氏阳性菌，短杆状，有运动性，芽孢很少见，生长必须因子包括酵母粉和维生素 B 族；最适碳源为果糖，最适生长温度35～37℃，最适 pH 值为6．0～7．0。合成气发酵实验结果显示：37℃，厌氧静止发酵30d，乙醇最高产量达到2．58g/L，添加 BESA、莫能菌素、丁基橡胶颗粒可以使乙醇产量分别提高49％、70％、4．3％，最大产量达到4．31g/L。[结论]从动物粪便中分离到1株 Clostridium ljungdahlii ，该菌能够利用合成气生产乙醇，为进一步研究和开发新型生物质材料提供了基础资料。

[Objective]To isolate and identify a microbial strain capable of producing ethanol from syngas fermentation from animal waste.[Methods]The enrichment culture using syngas as the sole carbon source was utilized to isolate the strain,which was identified according to the ob-servation of morphology,physiological and biochemical tests,and analysis of 16S rRNA gene sequences.The isolated strain was utilized for preliminary fermentation.[Results]A strain ca-pable of fermenting syngas into ethanol was isolated successfully.The strain was identified as Clostridium ljungdahlii ,which is a strict anaerobe and gram-positive.The cells are rod-shaped and show motility;spores are formed in-frequently;the strain requires a minimum level of yeast extract （0.1%） and B-vitamins for growth;substrate optimum is fructose;temper-ature optimum range is 35 ~37℃;pH optimum range is 6.0 ~ 7.0;batch fermentation reveals that under anaerobic conditions the highest yield of ethanol in serum bottles at 37℃ was 2.58g/L after 30d;by addition of BESA,monensin and butyl rubber particles yields of ethanol can in-crease 49%,70% and 4.3%,respectively,with the highest yield of ethanol at 4.31g/L.[Con-clusion]Clostridium ljungdahlii was capable of producing ethanol from syngas fermentation.