摘要
从金银花植株茎中分离到了1株具有谷氨酸脱羧酶活性的内生细菌,1g菌体(DW)24h可将241.224μmolL-Glu转化生成GABA。通过引物设计,利用PCR扩增出该菌株的16SrDNA序列,大小为1459bp。通过形态特征、生理生化特征和16SrDNA序列分析鉴定EJH-7为巨大芽孢杆菌(Bacillus megaterium)。同时基于16SrDNA构建了系统进化树,并对EJH-7进行了系统发育分析。Bacillus megateriumEJH-7细胞转化谷氨酸生成GABA的最适反应温度和pH分别为30℃和5.5;表面活性剂Tween20和Tween80对转化反应活性有抑制作用,而Triton100影响不显著;Ca2+、Cu2+和Co2+对转化反应活性有促进作用,分别提高了20.36%、46.61%和6.77%,而K+、Fe2+、Zn2+、Mg2+和Mn2+有不同程度的抑制作用。
An endophytic bacterium strain EJH-7 with glutamate decarboxylase activity, transforming 241.224μ mol L- glutamate to GABA in 24h by lg cell （DW）, was isolated and screened from the stem of Lonicerajaponica Thunb. Through the morphologic, physiological and biochemical characteritics and the 16S rDNA sequence analysis, EJH-7 has been identified as Bacillus megaterium. Also, the phylogenesis was analyzed through the phylogenetic tree base on the 16S rDNA sequences, indicating that strain EJH-7 belonged to Bacteria, Firmicutes, Bacillales, Bacillaceae, Bacullus. The properties of the bioTRansformation （converting L-glutamate to GABA） of Bacillus megaterium EJH-7 were also examined. As a result, the optimum temperature and pH value for bioWansformation are 30℃ and 5.5 respectively. The bioWansformation activities are inhibited by Tween 20 and Tween 80, and hardly affected by Triton 100. The biotransformation activities of Bacillus megaterium EJH-7 are significantly increased by 2.5mmol/L of Ca^2＋, Cu^2＋ and Co^2＋, and raised by 20.36%, 46.61% and 6.77% respectivelyin different degree by K^＋, Fe^2＋, Zn^2＋, Mg^2＋ and Mn^2＋.
出处
《食品科学》
EI
CAS
CSCD
北大核心
2007年第2期196-202,共7页
Food Science
