1株产丝氨酸羟甲基转移酶菌株的分离鉴定及其培养条件优化

Isolation,Identification and Optimizing Conditions of a Newly SHMT Producing Bacterium

从甲醇污染土壤中分离得到1株能在含2%甲醇的培养基上生长且产丝氨酸羟甲基转移酶(SHMT)的菌株,ML206,酶活达到0.030 U/mL。将ML206菌株的16S rDNA序列(No.EF612770)和GenBank数据库中已报道的16S rDNA序列进行Blast比对和系统发育分析,结合形态学和生理生化鉴定结果,确定ML206为嗜胺甲基杆菌(M.aniovorans)。经过对产酶条件的优化确定最佳氮源、碳源及培养件为:(NH_4)_2 HPO_4 0.8%,CH_3OH 2%,pH 7.0,温度30℃;采用分批的方式添加甲醇,培养时间由72 h缩短至48 h,节省了33%的培养时间。在优化的培养条件基础上进行实验,菌体浓度比原来提高了50%,SHMT活力提高了20%。经过对该菌的各种特性的研究确定了其为1株良好的产SHMT的新型出发菌。

The serine hydroxymethyltransferase（SHMT） was produced under the conditions of 2% methanol by a newly isolated facultative methylotrophic bacterium, strain ML206, which was isolated from methanol-polluted soil, the SHMT activity attained to 0. 030U/mL. Based on the analysis of morphology and some biochemical and physiological characteristics, strain ML206 was identified as Methylobacterium aminovorans combined with the analysis of 16S rDNA gene sequence and phylogenetic tree. According to optimization condition of cell growth and enzyme production,the initial pH is 7.0 and temperature is 30℃. The medium showed efficient activity of SHMT with addition of （NH4）2HPO4 （0.8%） and CH3OH （20%） as nitrogen and carbon sources respectively. When changed the manner of adding CH3 OH, the bacterium concentration and SHMT activity were increased by 50%, 20% respectively. This paper supplement some characteristic introductions and the production characteristic of the newly SHMT producing strain.