1 材料与方法
1.1 试验材料
表1 牦牛酸奶营养成分Table 1 Nutrient composition in yak yoghurt |
| 项目 Items | 每100 g含量 Content per 100 g | 营养 参考值 NRV/% |
|---|---|---|
| 能量Energy | 2 110 kJ | 25 |
| 蛋白质Protein | 25.8 g | 43 |
| 脂肪Fat | 29 g | 48 |
| 多不饱和脂肪酸PUFA | 0.7 g | |
| 碳水化合物Carbohydrate | 35.2 g | 12 |
| 钠Sodium | 350 mg | 18 |
| 维生素A Vitamin A | 150 mg | 19 |
| 维生素E Vitamin E | 0.3 μg | 2 |
| 维生素B1 Vitamin B1 | 0.1 mg | 7 |
| 维生素B2 Vitamin B2 | 0.7 mg | 50 |
| 维生素B6 Vitamin B6 | 0.13 mg | 9 |
| 烟酸Niacin | 0.34 mg | 2 |
| 泛酸Pantothenic acid | 1.1 mg | 22 |
| 胆碱Choline | 50 mg | 11 |
| 磷Phosphorus | 600 mg | 86 |
| 钾Potassium | 700 mg | 35 |
| 镁Magensium | 55 mg | 18 |
| 钙Calcium | 900 mg | 113 |
| 锌Zinc | 3 mg | 20 |
| 碘Iodine | 50 μg | 33 |
| 硒Selenium | 5 μg | 10 |
| 左旋肉碱L-carnitine | 10 mg |
1.2 主要试剂与仪器设备
1.3 菌株的分离纯化
表2 引物序列Table 2 Primer sequences |
| 引物Primers | 序列Sequences(5'—3') | 位点Position |
|---|---|---|
| 27F | AGAGTTTGATCCTGGCTCAG | 7 |
| 1492R | GGTTACCTTGTTACGACTT | 1 159 |
| rpoA 21F | ATGATYGARTTTGAAAAACC | 1 |
| rpoA 23R | ACHGTRTTRATDCCDGCRCG | 802 |
1.4 菌株生长曲线测定
1.5 菌株耐酸和耐胆盐能力测定
1.6 菌株自动聚集能力测定
1.7 菌株疏水性测定
1.8 菌株抑菌能力测定
1.9 菌株抗生素耐药性测定
1.10 菌株对结肠细胞的黏附能力测定
1.11 菌株抗氧化能力测定
1.11.1 样品的制备
1.11.2 2,2-二苯基-1-苦基肼(2,2-diphenyl-1-picrylhydrazyl,DPPH)自由基清除率、羟自由基清除率及还原能力测定
1.12 RAW264.7细胞活力的测定
1.13 一氧化氮(NO)生成的测定
1.14 数据统计分析
2 结果与分析
2.1 分离菌株的形态和镜检
表3 牦牛源样品部分菌株的鉴定结果Table 3 Identification results of some strains of yak source samples |
| 菌株 Strains | 菌株编号 Strain number | GenBank登录号 GenBank accession No. | 相似性 Similarity/% |
|---|---|---|---|
| 罗伊氏黏液乳杆菌Limosilactobacillus reuteri | QM11 | MF461465.1 | 99.86 |
| 植物乳植杆菌Lactiplantibacillus plantarum | ML01 | KC836663.1 | 99.56 |
| 植物乳植杆菌Lactiplantibacillus plantarum | MT08 | MT544918.1 | 98.90 |
| 植物乳植杆菌Lactiplantibacillus plantarum | MD05 | JQ801725.1 | 99.44 |
| 屎肠球菌Enterococcus faecium | QL05 | CP034949.1 | 99.74 |
| 屎肠球菌Enterococcus faecium | QL08 | CP034949.1 | 99.48 |
| 屎肠球菌Enterococcus faecium | QL10 | CP034949.1 | 99.61 |
| 屎肠球菌Enterococcus faecium | QL16 | CP034949.1 | 99.48 |
2.2 菌株生长曲线
2.3 菌株耐酸和耐胆盐能力
2.4 菌株自动聚集能力和疏水性
2.5 菌株抑菌能力
表4 不同菌株的抑菌能力Table 4 Bacteriostatic capacity of different strains % |
| 菌株编号 Strain number | 抑菌率Inhibition rate | 菌株编号 Strain number | 抑菌率Inhibition rate | |||
|---|---|---|---|---|---|---|
| 大肠杆菌QH01 Escherichia coli QH01 | 金黄色葡萄球菌 Staphylococcus aureus | 大肠杆菌QH01 Escherichia coli QH01 | 金黄色葡萄球菌 Staphylococcus aureus | |||
| QM11 | 86.46±1.13 | 85.77±1.35 | QL05 | 80.52±0.36 | 85.34±1.55 | |
| ML01 | 71.34±0.94 | 87.74±0.45 | QL08 | 71.11±1.42 | 81.35±1.65 | |
| MT08 | 74.53±0.93 | 77.14±1.37 | QL10 | 71.23±0.90 | 82.14±0.82 | |
| MD05 | 83.46±1.12 | 75.32±0.94 | QL16 | 60.92±1.29 | 77.24±0.94 | |
表5 罗伊氏黏液乳杆菌QM11的抑菌能力Table 5 Bacteriostatic capacity of Limosilactobacillus reuteri QM11 % |
| 指示菌 Indicator bacteria | 抑菌率 Inhibition rate | 指示菌 Indicator bacteria | 抑菌率 Inhibition rate | |
|---|---|---|---|---|
| 大肠杆菌O157 Escherichia coli O157 | 89.21±0.62 | 志贺氏菌Shigella castellani | 97.05±0.41 | |
| 大肠杆菌QH01 Escherichia coli QH01 | 87.29±0.98 | 鼠伤寒沙门氏菌Salmonella typhimurium | 74.29±1.88 | |
| 大肠杆菌QH02 Escherichia coli QH02 | 74.67±1.28 | 阪崎克罗诺杆菌Cronobacter sakazakii | 85.68±1.09 | |
| 大肠杆菌QH03 Escherichia coli QH03 | 86.43±0.21 | 金黄色葡萄球菌Staphylococcus aureus | 87.85±1.16 | |
| 单增李斯特菌Listeria monocytogenes | 91.95±0.50 |
2.6 菌株抗生素耐药性
表6 罗伊氏黏液乳杆菌QM11的抗生素耐药性Table 6 Antibiotic resistance of Limosilactobacillus reuteri QM11 |
| 抗生素 Antibiotics | 每片含量 Content per tablet | 抑菌圈 直径 Inhibition circle diameter/ mm | 敏感性 Sensitivity | 抗生素 Antibiotics | 每片含量 Content per tablet | 抑菌圈 直径 Inhibition circle diameter/ mm | 敏感性 Sensitivity | |
|---|---|---|---|---|---|---|---|---|
| 氨苄西林Ampicillin | 10 μg | 44.58±0.75 | S | 诺氟沙星Norfloxacin | 10 μg | 0.00±0.00 | R | |
| 苯唑西林Oxacillin | 1 μg | 0.00±0.00 | R | 头孢噻吩Cefalotin | 30 μg | 40.40±1.08 | S | |
| 青霉素Penicillin | 10 IU | 32.50±1.03 | S | 万古霉素Vancomycin | 30 μg | 35.15±1.37 | S | |
| 庆大霉素Gentamicin | 10 μg | 32.79±1.48 | S | 环丙沙星Ciprofloxacin | 5 μg | 0.00±0.00 | R | |
| 链霉素Streptomycin | 10 μg | 27.74±1.95 | S | 左氧氟沙星Levofloxacin | 5 μg | 0.00±0.00 | R | |
| 四环素Tetracycline | 30 μg | 36.85±1.27 | S | 氨曲南Aztreonam | 30 μg | 20.36±0.84 | I | |
| 氯霉素Chloramphenicol | 30 μg | 39.78±0.51 | S | 头孢他啶Ceftazidime | 30 μg | 29.82±1.09 | S | |
| 呋喃妥因Furadantin | 300 μg | 40.61±2.86 | S | 卡那霉素Kanamycin | 30 μg | 23.77±2.00 | S |
S:敏感 sensitive;I:中度敏感 moderately sensitive;R:耐药 resistant。 |
2.7 菌株对结肠细胞的黏附能力
2.8 菌株抗氧化能力
表7 菌株抗氧化能力Table 7 Antioxidant capacity of strains % |
| 菌株 Strains | 处理方式 Treatments | DPPH自由基清除率 DPPH radical scavenging rate | 羟自由基清除率 Hydroxyl radical scavenging rate | 还原能力 Reducing ability |
|---|---|---|---|---|
| 罗伊氏黏液乳杆菌QM11 Limosilactobacillus reuteri QM11 | 发酵上清液 | 89.42±0.75 | 37.97±2.28b | 16.73±1.47 |
| 菌悬液 | 4.19±1.03 | 180.29±9.28a | 6.07±0.60a | |
| 无菌体破碎物 | 38.57±8.16a | 95.57±2.91 | 3.63±1.62 | |
| 鼠李糖乳杆菌GG Lactobacillus rhamnosus GG | 发酵上清液 | 89.25±1.19 | 92.58±0.06a | 15.77±1.25 |
| 菌悬液 | 2.83±0.95 | 92.31±0.96b | 1.47±0.42b | |
| 无菌体破碎物 | 15.62±2.75b | 99.80±4.71 | — |
“—”表示清除率较低(<0.5%)。不同字母代表不同菌株相同处理方式差异显著(P<0.05)。 | |
“—”indicated low scavenging rate (<0.5%). Different letters represented significant differences between different strains of the same treatment (P<0.05). |
2.9 菌株对LPS诱导RAW264.7细胞NO生成的影响
图9 菌株对LPS诱导RAW264.7细胞活力的影响Fig.9 Effects of strains on viability of RAW264.7 cells induced by LPS |
图10 菌株对LPS诱导RAW264.7细胞NO生成的影响“#”代表LPS组与对照组相比差异显著(P<0.05),“*”代表不同浓度处理组与LPS组相比差异显著(P<0.05)。 Fig.10 Effects of strains on NO production of RAW264.7 cells induced by LPS “#” represented significant difference between LPS group and control group (P<0.05), and “*” represented significant difference between different concentration treatment groups and LPS group (P<0.05). |
