一株嗜碱产甲烷八叠球菌的分离鉴定与系统发育分析

在15℃条件下用产甲烷菌培养基对采自四川省红原县的牦牛粪进行富集培养,采用Hungate厌氧操作技术从富集培养物中分离得到一株在8~45℃范围生长、最适生长pH为8.5的嗜碱产甲烷菌T13.该菌株革兰氏染色阳性,细胞聚集体,在液体培养基中为肉眼可见的颗粒状物,在固体培养基上菌落为淡黄色桑葚状;可利用甲醇、乙酸盐和甲胺作为唯一碳源生长;对氯霉素和庆大霉素敏感;生长pH范围为6.5~9.5;最适NaCl浓度为0~0.15 mol L-1;最适生长温度为30℃.形态和生理生化特征以及16S rDNA序列分析表明菌株T13为梅氏产甲烷八叠球菌(Methanosarcina mazei).由于该菌最适生长pH为8.5,所以初步认为菌株T13是一株梅氏产甲烷八叠球菌的新菌株.

Isolation, Identification and Phylogenetic Analysis of an Alkalophilic Methanosarcina

An alkalophilic methanogen T13 was isolated by anaerobic techniques of Hungate from cow muck in Hongyuan county,Sichuan,China enriched in culture for methanogen at 15 ℃.Its optimum pH for producing methane was 8.5,and the temperature for growth was observed at the range of 8~45 ℃.The culture was visible particulate.Cells were aggregated and gram-positive.The colony was pale yellow,mulberry-like and fluoresced.T13 could grow using acetate,methanol or methylamine as sole carbon source,and it was sensitive to chloramphenicol and gentamicin.The optimum temperature and NaCl concentration for its growth were 30 ℃ and 0~0.15 mol L-1,respectively.It grew at the pH range between 6.5 and 9.5.The morphological and physio-biochemical characteristics combined with 16S rDNA sequence analysis of strain T13 demonstrated that it was a strain of Methanosarcina mazei.Since its optimum pH for growth was 8.5,strain T13 therefore was considered preliminarily as a new strain of M.mazei.