新疆传统奶酪中抗氧化乳酸菌筛选及培养条件优化

Screening and optimization of culture conditions for antioxidant lactic acid bacteria in Xinjiang traditional cheese

新疆传统奶酪中富含大量乳酸菌,为了得到具有抗氧化活性的乳酸菌,该文以新疆传统奶酪中筛选出的161株乳酸菌为研究对象,通过测试过氧化氢耐受性、羟自由基清除能力、超氧阴离子自由基清除能力、还原能力、金属离子螯合能力、DPPH自由基清除能力,综合评估菌株的抗氧化性。结果表明,有12株乳酸菌具有较高抗氧化活性,其中菌株S2-7发酵上清液对羟自由基、超氧阴离子自由基、DPPH自由基清除能力较好,分别为95.28%、90.17%、88.22%;菌株B6-4、S4-14菌悬液具有较好的还原能力及亚铁离子螯合能力,分别为92.75%、95.85%。将这12株乳酸菌经过模拟人工胃肠液及胆盐耐受测定,8株展现出良好的耐受性。经16S rDNA鉴定,7株为乳酸片球菌;1株为干酪乳杆菌。优化其培养条件,得到培养基初始pH(6.5~7.5)、培养时间(18~28 h)、培养温度(37~42℃)、接种量(2%~3%),研究结果将对优质菌种的开发提供数据支持。

Xinjiang traditional cheese is rich in lactic acid bacteria.In order to obtain lactic acid bacteria with antioxidant activity,161 strains of lactic acid bacteria were selected from Xinjiang traditional cheese for this study.The antioxidant activity of the strains was evaluated by testing the hydrogen peroxide tolerance,·OH scavenging ability,·O-2 scavenging ability,reducing ability,metal ion chelating ability,and DPPH free radical scavenging ability.The results showed that 12 strains of lactic acid bacteria had high antioxidant activity,among which the fermentation supernatant of strain S2-7 had better scavenging ability of·OH,·O-2,and DPPH free radical,95.28%,90.17%,and 88.22%,respectively;strains B6-4 and S4-14 suspensions had better reducing ability and ferrous ion chelating ability,92.75%,and 95.85%,respectively.The 12 strains were subjected to a simulated artificial gastrointestinal fluid and bile salt tolerance assay,and eight strains showed good tolerance.Seven strains were identified by 16S rDNA as Lactococcus lactis and one strain of Lactobacillus casei.Their culture conditions were optimized,with the initial pH of 6.5-7.5,incubation time of 18-28 h,37-42℃,and inoculum of 2%-3%.The findings of this study will provide data to support the development of high-quality strains.