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

关键词:  合成气  厌氧发酵  梭状芽孢杆菌  乙醇

Key words:  syngas  anaerobic fermentation  Clostridium ljungdahlii  ethanol

摘要:

[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。

Abstract:

[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 observation of morphology, physiological and biochemical tests, and analysis of 16S rRNA gene sequences.The isolated strain was utilized for preliminary fermentation.[Results] A strain capable 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 infrequently; the strain requires a minimum level of yeast extract(0.1%) and B-vitamins for growth; substrate optimum is fructose; temperature 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 increase 49%, 70% and 4.3%, respectively, with the highest yield of ethanol at 4.31g/L.[Conclusion] Clostridium ljungdahlii was capable of producing ethanol from syngas fermentation.