清香酒醅来源Lactobacillus plantarum SL32-2自溶酶的酶学性质及其底物特异性初探

Enzymatic properties and substrate specificity of autolysin from Lactobacillus plantarum SL32-2 derived from fermented grains of light-flavor Baijiu

为研究Lactobacillus plantarum SL32-2自溶酶的酶学性质及底物特异性,以该细菌细胞为底物分析其自溶酶的最适温度及最适pH,结合该菌株在有无外加自溶酶、自溶前后还原糖和氨基酸的变化以及对4种底物的敏感性,分析其自溶酶的底物特异性。结果表明,L.plantarum SL32-2在对数早期培养4 h时,自溶度最高;其自溶酶的最适pH为7.5,最适温度为37℃;添加自溶酶后,L.plantarum SL32-2的自溶度增加了12.04%、还原糖和氨基酸分别增加了1.05和42.83倍;底物特异性分析发现,L.plantarum SL32-2自溶酶中β-N-乙酰葡萄糖胺酶、酰胺酶、羧肽酶、内肽酶的活性分别为0.0036、0.0027、1.1267和2.0987 U,表明作用于肽链的酶活性远高于作用于糖链的酶。因此,有望通过添加自溶酶的方式,控制酒醅中乳酸菌的过量生长。

In order to study the enzymatic properties and substrate specificity of autolysin from Lactobacillus plantarum SL32-2,the optimal temperature and pH of the autolysin were analyzed with its bacterial cell as substrate;substrate specificity were analyzed with the concentration changes of reducing sugar and amino acids before and after autolysis with or without the addition the autolysin,as well as the sensitivity of four different substrates.The results showed that the autolysis rate of L.plantarum SL32-2 reached the highest when it was cultured for 4 h at the beginning of logarithmic growth stage.The optimal pH and temperature of its autolysin were 7.5 and 37℃,respectively.After adding autolysins,the autolysis rate of L.plantarum SL32-2 increased by 12.04%,and the concentration of reducing sugar and amino acids in buffers increased by 1.05 times and 42.83 times,respectively.For substrate-specific analysis,the activity ofβ-N-acetylglucamase,aminase,carboxyl peptidase and endopeptidase was 0.0036,0.0027,1.1267 and 2.0987 U,respectively,indicating that the enzyme activities acting on the peptide chain were higher than that on sugar chain.