一株高效降解木糖的耐酸、嗜热厌氧杆菌的生理特性及产物分析

Characterization of an acidotolerant，thermophilic Thermoanaerobacter sp．xyl-d with a high xylose conversion

摘要:

摘要:【目的】分离高效降解木糖的嗜热厌氧杆菌菌株，用于发酵生产生物燃料乙醇，为后继的构建基因工程菌株及联合生物工艺提供材料。【方法】运用亨盖特厌氧操作技术从胜利油田油层采出液两年的富集样中分离到一株嗜热厌氧杆菌xyl-d。采用形态学观察、生理生化指标鉴定及基于16S rRNA 的系统发育学分析确定其分类地位。【结果】菌株xyl-d 为革兰氏阴性厌氧杆菌，菌体大小为(1.35－5.08)μm×(0.27－0.40)μm，单生、成对或成簇生长，芽胞圆形，端生。温度生长范围30－85℃(最适温度65℃);pH

Abstract:

Abstract:［Objective］We screened a thermophilic xylolytic bacterium that produced fuel ethanol from a high-temperature oil reservoir，and provided microbial resources to genetic engineering strains construction and consolidated bioprocessing．［Methods］We adopted Hungate anaerobic technique to isolate strain xyl-d from oil reservoir water sample enriched for two years from Shengli Oilfield in China，and we identified strain xyl-d with morphological，physiological，biochemical and phylogenetic analysis．［Results］ Strain xyl-d was gram-negative，rod-shaped，spore-forming and strictly anaerobic．The growth temperature ranged from 30℃ to 85℃ (optimum 65℃) and the pH ranged from 3.0 to 10.0 (optimum 7.5) and salt concentration was 0%－4%(optimum at 2.0%)．It converted D-xylose into ethanol，acetate，CO2，trace amount of iso-butanol and propionate． The genomic DNA G + C contents of strain xyl-d was 45. 6 mol% ． Based on 16S rRNA gene sequence，strain xyl-d was most close to Thermoanaerobacter wiegelii DSM10319T and Thermoanaerobacter ethanolicus DSM 2246T both with the 99. 3% similarity． It produced more ethanol and less acetate at initial pH 8. 5 than other pH． Ethanol yield was increased significantly with yeast extract，and ethanol became the main end product． In addition，growth of strain xyl-d was inhibited obviously with ethanol concentration more than 7% (V/V)．In the optimum growth conditions，xylose degradation rates reached to 91.37%．［Conclusion］ Strain xyl-d was thermophilic，high xylose conversion rate，acidotolerant anaerobe． It was a potential bacterium that can be used for consolidated bioprocessing．