凝结芽孢杆菌RY237 β-半乳糖苷酶酶学性质研究

Characterization of β-galactosidase from Bacillus coagulans RY237

摘要: 为研究乳品中具有应用价值的乳糖酶,以乳糖为唯一碳源,用邻硝基苯酚-β-D-半乳糖苷（ONPG）法,从产乳酸的细菌中筛选出了产乳糖酶活力高的菌株RY237,其活性达4.98 U/m L,鉴定为凝结芽孢杆菌。研究了乳糖酶的酶学性质,该酶最适反应温度和最适p H分别为50℃和6.0。该酶在温度40⁵0℃具有良好的稳定性;p H5.5⁸.0表现稳定,p H7.0出现酶活峰值。金属离子Ca²⁺、K+、Zn²⁺、Mn²⁺、Na+、Mg²⁺对酶活具有抑制作用,Cu²⁺对酶活具有完全抑制作用,EDTA对酶活具有激活作用。凝结芽孢杆菌RY237乳糖酶活性高、性能优良,具有应用价值。

Abstract: A novel lactase-producing bacterium RY237 was selected based on β-galactosidase activity using lactose as sole carbon media, and was identified as Bacillus coagulans RY327. The activity of lactase reached 4.98 U/m L. The optimum temperature and optimum p H of β-galactosidase were 50 ℃ and 6.0, respectively. The enzyme was stable at p H5.5 ~ 8.0, with peak activity at p H7.0, and it was also stable at 40⁵0 ℃. The activity of β-galactosidase was inhibited by Ca²⁺, K+, Zn²⁺, Mn²⁺, Na+, Mg²⁺and completely inhibited by Cu²⁺. Its activity was promoted by ethylene diamine tetraacetic acid ( EDTA) .The high activity, thermostability and p H-stability make this enzyme potentially useful in dairy industry.