高产谷氨酸脱羧酶的菌株筛选及鉴定

Screening and Identification of Strains with High Production of Glutamate Decarboxylase

γ-氨基丁酸作为一种新型饲料添加剂,助推畜牧养殖业绿色健康发展。谷氨酸脱羧酶利用磷酸吡哆醛为辅因子将L-谷氨酸脱羧生成γ-氨基丁酸的转化方法得到了广泛关注。本研究利用平板活性筛选结合摇瓶发酵复筛的方法,从宁夏沙漠土样中筛选获得了3株具有较高谷氨酸脱羧酶活性的菌株。通过对菌落形态、16S rDNA序列比对和系统发育树分析,3株菌初步鉴定为芽孢杆菌属(Bacillus sp.),命名为Bacillus sp.Z1、Bacillus sp.Z11和Bacillus sp.Z20,保藏于中国农业微生物菌种保存中心。通过全基因组测序分析,发现三株菌分别含有一个谷氨酸脱羧酶编码基因。三条基因序列长度均为1470 bp,序列相似性为94.5%~97.3%,编码489个氨基酸和1个终止密码子,理论分子量55 ku。

As a new type of feed additive,the γ-aminobutyric acid promotes the green and healthy development of animal husbandry.Theγ-Aminobutyric acid can be produced through the biocatalyticα-decarboxylation of L-glutamic acid using glutamate decarboxylase with pyridoxal 5'-phosphate as cofactor,which has attracted widespread attention.In this study,three strains with high glutamate decarboxylase activity were obtained from desert soil samples in Ningxia Hui Autonomous Region by using the method of plate screening combined with shake flask fermentation rescreening.After the colony morphology analysis,16S rDNA sequence alignment and phylogenetic tree analysis,the three strains were preliminarily identified as Bacillus sp.,named Bacillus sp.Z1,Bacillus sp.Z11 and Bacillus sp.Z20,respectively.The strains were preserved in the China Agricultural Microbial Species Conservation Center.A whole genome sequencing analysis revealed that each of the strains contained a gene that codes for glutamate decarboxylase.The sequence length of the three genes was 1470 bp and shared 94.5%-97.3%sequence identities.The genes encoded 489 amino acids long polypeptide with a theoretical molecular mass of 55 ku.