青海牧区产凝乳酶细菌多样性分析

为发掘性能优良的产凝乳酶细菌菌株,开发新型细菌凝乳酶。本文采用酪蛋白培养基从采自青海牧区土壤样品分离筛选产凝乳酶细菌,利用菌株16S rDNA基因序列对菌株进行鉴定并分析其多样性。结果表明,36个样品中分离得到21株产凝乳酶细菌,沉淀圈与菌落直径比值为1.41~5.5;分离菌株在不同培养基上凝乳酶和蛋白水解活性有明显差异,麸皮汁培养基中凝乳酶活性为11.3~1215.6 SU/mL,蛋白水解活力为14.6~59.5U/mL;21株菌中有14株菌属芽孢杆菌属(Bacillus),是产凝乳酶细菌的优势属;多样性指数分析表明,该地区产凝乳酶细菌具有丰富多样性。

Diversity of Bacteria Producing Milk-clotting Enzymes in Qinghai Pastoral Area

To excavate fine milk-clothing enzyme producing strains and develop new type of milk-clothing enzyme from bacterial sources. Microorganisms with high milk-clotting activity from soil samples collecting form Qinhai pastoral area in Tibetan Plateau of China was isolated and screened. Strains isolated were identified by the 16S rRNA sequence similarity and the diversity was analyzed by the phyologentic tree. Results showed that a total of 21 bacterial strains producing milk-clotting enzymes were isolated from 36 soil samples. The ratio of deposition zone to the colony diameter among the isolated strains in the casein plate medium ranged from 1.41 to 5.5.Media affected the milk-clotting activity and proteolysis activitiy of bacteria obviously. Milk-clotting activity among the isolated strains ranged from 11.3 to 1215.6 SU/mL in wheat bran juice medium,and proteolysis activitiy was between 14.6 and 59.5 SU/mL. Out of 21 strains,there were 14 strains found to be in the genus of Bacillus,implying that Bacillus was the most dominant genus of bacteria producing milk-clotting enzymes. The analysis indicated that the diversity of bacteria producing milk-clotting enzymes in Qinhai pastoral area was high.