宫廷奶酪中优良乳酸菌菌株的分离与鉴定

利用梯度稀释法和划线纯化法对4种宫廷奶酪中的乳酸菌进行初筛,再通过产酸实验和过氧化氢酶实验进行复筛,得到4株乳酸菌。通过形态学特征观察和16S rDNA序列分子鉴定,确定2株为屎肠球菌(MRSA1、MRSB1),2株为乳明串珠菌(MRSA2、MRSD3)。抑菌实验表明乳明串珠菌MRSA2对大肠杆菌、志贺氏菌、沙门氏菌具有良好的抑菌特性；4株菌均有抗氧化活性,菌悬液的DPPH自由基清除能力和羟自由基清除能力均高于无细胞提取物,其中菌株MRSA2菌悬液DPPH自由基和羟自由基清除能力分别高达60.67%和31.86%。研究筛选出的具有良好抑菌特性和抗氧化活性的乳明串珠菌MRSA2在功能性食品研发中具有潜在的应用价值。

Isolation and Identification of Lactic Acid Bacteria from Traditional Royal Cheese

In this study, four strains of lactic acid bacteria were obtained from four kinds of traditional royal cheese using gradient dilution method and scribing purification method, and then rescreened by acid production experiment and catalase experiment. Through morphological observation and molecular identification of 16S rDNA sequence, two strains were identified as Enterococcus faecium (MRSA1 and MRSB1), and the other two strains were identified as Leuconostoc lactis (MRSA2 and MRSD3). The bacteriostatic test showed that Leuconostoc lactis(MRSA2) had good antibacterial properties against Escherichia coli, Shigella and Salmonella. All four strains had antioxidant activities, and the DPPH radical scavenging ability and hydroxyl radical scavenging ability of the bacterial suspension were higher than those of cell-free extracts. The DPPH and hydroxyl radical scavenging ability of MRSA2 suspension were 60.67% and 31.86%. The strains of lactic acid bacteria (MRSA2) with antibacterial and antioxidative activities obtained in this study provided a foundation for their application in functional dairy foods.