一株分离自西藏高山草甸土壤的肠球菌的分离鉴定及代谢特征

Isolation and characterization of an Enterococcus strain from Tibetan alpine meadow soil

摘要:

摘要:【目的】了解高海拔低温缺氧条件下土壤环境中微生物生理生化特性及代谢产物【方法】采用Hungate厌氧操作技术从西藏纳木措高山草甸土壤中分离到一株肠球菌CJ-1。通过生理生化特征分析和16S rRNA基因序列的系统发育学分析确定该菌株的系统发育学地位。【结果】菌株CJ-1为兼性厌氧的革兰氏阳性菌，菌体呈不规则球形，大小为直径约1μm－1.5 μm，无鞭毛，不运动，成串珠型或成对排列。生长温度范围为10℃－50℃(最适温度为25℃);pH范围为5.0－8.5(最适pH 为7.0);NaCl浓度为0%－7%(最适NaCl浓度为5%)。能够利用葡萄糖、核糖、松三糖以及纤维二糖等多种碳水化合物，发酵纤维二糖的产物是乳酸、乙酸、丙酸、CO2、H2以及少量的丁酸。菌株CJ-1 的(G+C) Mol%为39.2%。与Enterococcus aquimarinus(CCM7283)的相似性达95.9%。菌株可利用纤维二糖，其在沼气发酵过程中充当中间代谢物。【结论】菌株CJ-1为耐低温肠球菌，可以降解纤维二糖等，且适应性较强，在发酵过程中具有重要意义，将其暂定命名为Enterococcus namtsoensis，模式菌株DSM23475T(=ACCC 00521T)。

Abstract:

Abstract:［Objective］We studied the physiological，biochemical properties and metabolism of Enterococcus strain CJ-1 from high-altitude soil in Namtso，Tibet． ［Methods］Strain CJ-1T was isolated from the soil of Namtso alpine meadow soil by Hungate anaerobic technique． Through physiological，biochemical and phylogenetic analysis，we identified the strain CJ-1. ［Results］Strain CJ-1 was Gram-positive and facultative anaerobe，1－1.5μm in diameter． CJ-1T was atrichia nonmotile cocci，and always occurred in pairs． CJ-1T occurred in the presence of 0%－7% NaCl (optimum at 5%)，pH 5.0－8.5 (optimum 7.0) and temperature between 10℃ and 50℃ (optimum at 25℃)．CJ-1 could metabolize many carbon sources including cellobiose，melezitose and ribose． Metabolites of cellobiose were lactic acid，acetic acid，propionic acid，butyrate，CO2，and little H2 ． The mol% G + C content of the genomic DNA was 39.2 mol%．16S rRNA gene sequence analysis of the above strain showed the highest similarity of 95. 9% with its closest phylogenetic neighbor Enterococcus aquimarinus． The strain can degrade cellobiose which act as intermediate metabolites in the methane fermentation process． ［Conclusion］CJ-1T can degrade cellobiose． CJ-1T represents a novel species in the genus Enterococcus．