新疆传统乳制品中产蛋白酶乳酸菌的筛选及产酶条件优化

以新疆传统发酵乳制品为分离源，分离筛选产蛋白酶的乳酸菌，并通过形态学观察及16S rDNA序列比对鉴定菌株。以碳源、氮源、金属盐、磷酸盐的种类和添加量为影响因素，以蛋白酶活作为评价指标，通过单因素试验和正交试验优化乳酸菌产蛋白酶的产酶条件。结果表明，从样品中分离筛选出乳酸菌16株，产蛋白酶的乳酸菌4株（编号为A1～A4），分别被鉴定为戊糖片球菌（Peciococcus pentosaceus）、发酵乳杆菌（Lactobacillus fermentum）、短乳杆菌（Lactobacillxus brevis）、乳酸明串珠菌（Leuconostoc lactis）。在以4.0%葡萄糖为碳源、4.0%牛肉膏为氮源、0.02%的镁离子为金属盐、0.7%的K2HPO4为磷酸盐的条件下，菌株A2产蛋白酶活最高为65.92 U/mL。

Screening of protease-producing lactic acid bacteria from Xinjiang traditional dairy products and optimization of enzymatic production conditions

Taking Xinjiang traditional fermented dairy products as the separation source, the protease-producing lactic acid bacteria were isolated and screened, and the strains were identified by morphological observation and 16S rDNA sequence comparison. Taking the types and addition of carbon source, nitrogen source, metal salt and phosphate as influencing factors, and protease activity as evaluation index, the protease production conditions of lactic acid bacteria were optimized by single factor tests and orthogonal tests. The results showed that 16 strains of lactic acid bacteria and 4 strains of protease-producing lactic acid bacteria were isolated and screened from the samples, (numbered A1-A4), and they were identified as Pureococcus pentosaceus, Lactobacillus fermentum, Lactobacillxus brevis and Leuconostoc lactis. Under the conditions of glucose 4.0% as carbon source, beef extract 4.0% as nitrogen source, magnesium ion 0.02% as metal salt, K2HPO4 0.7% as phosphate, the strain A2 could produce the highest protease activity of 65.92 U/ml.