1 材料与方法
1.1 试验材料
1.2 试验方法
1.2.1 乳酸菌的初筛
1.2.2 乳酸菌的复筛
1.2.3 乳酸菌的鉴定
1.2.3.1 形态学鉴定
1.2.3.2 生理生化鉴定
1.2.3.3 分子生物学鉴定
1.2.4 乳酸菌益生特性的测定
1.2.4.1 生长能力和产酸能力测定
1.2.4.2 酸和胆盐耐受性
1.2.4.3 耐渗透压性
1.2.4.4 自凝集率和表面疏水率测定
1.2.5 安全性检验
1.2.5.1 乳酸菌溶血试验
1.2.5.2 乳酸菌抗生素敏感性试验
1.2.5.3 乳酸菌抑菌性试验
1.3 数据统计分析
2 结果与分析
2.1 乳酸菌初筛结果
表1 乳酸菌对4种毒素的降解率Table 1 Degradation rates of 4 kinds of toxins by LBA% |
| 菌株编号 Strain numbers | 黄曲霉毒B1 AFB1 | 呕吐毒素 DON | 玉米赤霉烯酮 ZEA | 硫代葡萄糖苷 GLUS |
|---|---|---|---|---|
| B1 | 64.13±3.12bcd | 60.11±1.15a | 36.02±2.82cde | 42.07±2.11cde |
| B8 | 64.43±2.44bcd | 25.91±0.79ef | 40.14±3.30bc | 40.31±3.56def |
| A7 | 41.30±4.54f | 47.39±0.57b | 61.31±4.22a | 28.24±4.69gh |
| C24 | 62.69±2.56cd | 27.69±2.78ef | 21.69±3.70gh | 50.06±4.25b |
| D4 | 41.54±2.52f | 29.47±2.25de | 26.82±3.04fg | 34.71±1.68fg |
| C2 | 70.95±1.85a | 13.50±3.20j | 31.44±5.99def | 48.44±3.52bc |
| C16 | 69.10±3.04ab | 45.01±2.35b | 38.54±4.26bcd | 58.91±2.54a |
| D3 | 45.08±1.08f | 48.92±3.93b | 64.00±5.57a | 51.62±1.78b |
| A16 | 41.47±2.81f | 38.83±3.25c | 45.07±4.67b | 22.36±3.51hi |
| C1 | 66.24±1.38abc | 33.69±3.10cd | 60.64±2.31a | 59.19±4.14a |
| D17 | 45.19±5.52f | 23.10±0.82f | 28.67±3.36efg | 45.65±1.31bcd |
| E12 | 59.01±2.80d | 36.54±1.82c | 16.28±0.75h | 36.61±2.28ef |
| E11 | 59.09±1.89d | 35.72±3.14c | 33.59±4.85cdef | 51.40±3.59b |
| E28 | 60.47±1.27d | 48.34±2.27b | 32.31±1.80def | 18.46±4.29i |
| A17 | 53.23±0.72e | 44.27±3.68b | 56.90±1.38a | 47.13±2.14bc |
同列数据肩标相同字母表示差异不显著(P>0.05),不同字母表示差异显著(P<0.05)。 | |
In the same column, values with the same letter superscripts mean no significant difference (P>0.05), while with different letter superscripts mean significant difference (P<0.05). |
2.2 乳酸菌脱毒曲线
2.3 乳酸菌鉴定结果
2.3.1 形态学鉴定结果
图2 部分菌株菌落形态及革兰氏染色A为不同菌株菌落形态,B为对应菌株革兰氏染色。 Fig.2 Colony morphology and Gram staining of some strains (63×) A showed colony morphology of different strains, and B showed Gram staining of corresponding strains. |
表2 乳酸菌形态特征Table 2 Morphological characteristics of LAB |
| 菌株编号 Strain numbers | 平板观察 Plate observation | 显微镜观察 Microscopic examination | 液体培养 Fluid culture | |||||
|---|---|---|---|---|---|---|---|---|
| 颜色 Colour | 形状 Shape | 表面 Surface | 边缘 Edge | 透明度 Transparency | 清浊 Pure and turbid | 浮膜 Pellicle | ||
| B1 | 乳白色 | 圆形微隆 | 光滑、湿润 | 整齐 | 透明 | 球状 | + | - |
| B8 | 白色 | 圆形微隆 | 光滑、湿润 | 整齐 | 不透明 | 杆状 | + | - |
| A7 | 乳白色 | 圆形液滴状 | 光滑、湿润 | 整齐 | 透明 | 球状 | + | - |
| C24 | 淡黄色 | 圆形微隆 | 光滑、湿润 | 整齐 | 不透明 | 球状 | + | - |
| D4 | 白色 | 圆形微隆 | 光滑、湿润 | 整齐 | 不透明 | 杆状 | + | - |
| C2 | 白色 | 圆形微隆 | 光滑、湿润 | 整齐 | 不透明 | 球状 | + | - |
| C16 | 白色 | 圆形、中央凸起 | 光滑、湿润 | 整齐 | 不透明 | 杆状 | + | - |
| D3 | 白色 | 圆形微隆 | 光滑、湿润 | 整齐 | 不透明 | 杆状 | + | - |
| A16 | 白色 | 圆形微隆 | 光滑、湿润 | 整齐 | 不透明 | 球状 | + | - |
| C1 | 白色 | 圆形微隆 | 光滑、湿润 | 整齐 | 不透明 | 球菌 | + | - |
| D17 | 白色 | 圆形微隆 | 光滑、湿润 | 整齐 | 不透明 | 杆状 | + | - |
| E12 | 乳白色 | 圆形微隆 | 光滑、湿润 | 整齐 | 不透明 | 球状 | + | - |
| E11 | 乳白色 | 圆形微隆 | 光滑、湿润 | 整齐 | 不透明 | 球状 | + | - |
| E28 | 乳白色 | 圆形微隆 | 光滑、湿润 | 整齐 | 不透明 | 杆状 | + | - |
| A17 | 白色 | 圆形微隆 | 光滑、湿润 | 整齐 | 不透明 | 球状 | + | - |
2.3.2 生理生化鉴定结果
表3 乳酸菌生理生化特性Table 3 Physiological and biochemical characteristics of LAB |
| 菌株编号 Strain numbers | 产酸 Acid production | 产气 Gas production | 七叶苷 Aesculin | 甘露醇 Mannitol | 蔗糖 Sucrose | 麦芽糖 Maltose | 纤维 二糖 Cellobiose | 水杨苷 Salicin | 山梨醇 Sorbitol | 棉子糖 Raffinose | 吲哚 Indol | 明胶 Gelatin | 过氧化氢 Hydrogen peroxide | 硫化氢 Hydrogen sulfide |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| B1 | + | - | + | + | + | + | + | + | + | + | - | - | - | - |
| B8 | + | - | + | + | + | + | + | + | - | + | - | - | - | - |
| A7 | + | - | + | + | + | + | + | + | - | + | - | - | - | - |
| C24 | + | - | + | + | + | + | + | + | + | - | - | - | - | - |
| D4 | + | - | + | + | + | + | + | + | + | + | - | - | - | - |
| C2 | + | - | - | - | + | - | + | - | - | - | - | - | - | - |
| C16 | + | - | + | + | + | + | + | + | - | - | - | - | - | - |
| D3 | + | - | + | + | + | + | + | + | + | - | - | - | - | - |
| A16 | + | - | + | + | + | + | + | + | - | - | - | - | - | - |
| C1 | + | - | + | - | + | + | + | - | + | - | - | - | - | - |
| D17 | + | - | + | - | + | + | + | - | + | - | - | - | - | - |
| E12 | + | - | + | + | + | + | + | + | + | - | - | - | - | - |
| E11 | + | - | + | - | + | + | + | - | + | - | - | - | - | - |
| E28 | + | - | + | + | + | + | + | + | + | - | - | - | - | - |
| A17 | + | - | + | + | + | + | + | + | + | - | - | - | - | - |
2.3.3 分子生物学鉴定结果
图4 基因组DNA扩增前后的琼脂糖凝胶电泳A为基因组DNA的琼脂糖凝胶电泳图,B为PCR扩增后产物电泳图。M代表DL 2000 marker;1~15分别代表菌株B1、B8、A7、C24、D4、C2、C16、D3、A16、C1、D17、E12、E11、E28和A17。 Fig.4 Agarose gel electrophoresis before and after amplification of genomic DNA A showed agarose gel electrophoresis of genomic DNA, and B showed electrophoregram of products after PCR amplification. M represented DL 2000 marker; and 1 to 15 represented strains of B1, B8, A7, C24, D4, C2, C16, D3, A16, C1, D17, E12, E11, E28 and A17, respectively. |
表4 15株乳酸菌16S rRNA序列同源性比对结果Table 4 16S rRNA sequence homology comparison results of 15 strains of LAB |
| 菌株编号 Strain numbers | 菌种中文名称 Chinese name of strains | 菌株拉丁名称 Latin name of strains | 同源性 Homology/% | 登录号 Access number |
|---|---|---|---|---|
| B1 | 耐久肠球菌 | Enterococcus durans | 99.86 | MF077130.1 |
| B8 | 屎肠球菌 | Enterococcus faecium | 99.79 | JX317638.1 |
| A7 | 海氏肠球菌 | Enterococcus hirae | 99.86 | MF326336.1 |
| C24 | 蒙氏肠球菌 | Enterococcus mundtii | 99.93 | MZ869126.1 |
| D4 | 鼠李糖乳杆菌 | Lacticaseibacillus rhamnosus | 100.00 | MT613492.1 |
| C2 | 乳酸片球菌 | Pediococcus acidilactici | 99.93 | MT463569.1 |
| C16 | 乳肠球菌 | Enterococcus lactis | 100.00 | OM570328.1 |
| D3 | 鼠李糖杆菌 | Lacticaseibacillus rhamnosus | 99.93 | MT318646.1 |
| A16 | 戊糖片球菌 | Pediococcus pentosaceus | 100.00 | MT604839.1 |
| C1 | 短乳杆菌 | Levilactobacillus brevis | 100.00 | MT613460.1 |
| D17 | 短乳杆菌 | Levilactobacillus brevis | 100.00 | OR150693.1 |
| E12 | 戊糖片球菌 | Pediococcus pentosaceus | 100.00 | MT604839.1 |
| E11 | 海氏肠球菌 | Enterococcus hirae | 99.51 | MT473347.1 |
| E28 | 乳酸片球菌 | Pediococcus acidilactici | 99.78 | MT464296.1 |
| A17 | 戊糖片球菌 | Pediococcus pentosaceus | 99.86 | MK605953.1 |
图5 乳酸菌系统发育树Pediococcus pentosaceus:戊糖片球菌;Pediococcus acidilactici:乳酸片球菌;Lacticaseibacillus rhamnosus:鼠李糖杆菌;Levilactobacillus brevis:短乳杆菌;Enterococcus hirae:海氏肠球菌;Enterococcus lactis:乳肠球菌;Enterococcus durans:耐久肠球菌;Enterococcus faecium:乳肠球菌;Enterococcus mundtii:蒙氏肠球菌。 Fig.5 LAB phylogenetic tree |
2.4 乳酸菌益生特性
2.4.1 生长曲线和产酸曲线
2.4.2 酸和胆盐耐受性
2.4.3 耐渗透压性
2.4.4 自凝集率和表面疏水率
图9 乳酸菌自凝集率和表面疏水率A为乳酸菌自凝集率,B为乳酸菌表面疏水率。 数据柱标记不同字母表示差异显著(P<0.05)。 Fig.9 Self-agglutination rate and surface hydrophobic rate of LAB A showed self-agglutination rate of LAB, and B showed surface hydrophobic rate of LAB. Data columns with different letters indicated significant difference (P<0.05). |
2.5 乳酸菌安全性
2.5.1 溶血性和抗生素敏感性
2.5.2 抑菌性
表5 乳酸菌安全性测定结果Table 5 Safety test results of LAB |
| 菌株编号 Strain numbers | 溶血性 Hemolysis | 抗生素敏感性 Antibiotics sensitivity | |||||||
|---|---|---|---|---|---|---|---|---|---|
| 红霉素 Erythromycin | 氧氟沙星 Ofloxacin | 链霉素 Streptomycin | 青霉素 Penicillin | 四环素 Tetracycline | 庆大霉素 Gentamicin | 多黏菌素B Polymycin B | 环丙沙星 Ciprofloxacin | ||
| B1 | γ | I | I | R | I | S | R | I | I |
| B8 | γ | S | I | R | I | I | R | I | R |
| A7 | γ | S | S | R | I | S | R | R | S |
| C24 | γ | S | S | R | S | S | R | I | S |
| D4 | γ | I | S | R | S | S | R | I | I |
| C2 | γ | I | R | R | I | I | R | R | R |
| C16 | γ | S | R | R | S | I | R | I | R |
| D3 | γ | S | S | R | S | S | R | I | I |
| A16 | γ | S | R | R | S | S | R | R | R |
| C1 | γ | S | R | R | S | S | R | R | R |
| D17 | γ | S | R | R | I | I | R | I | R |
| E12 | γ | S | R | R | S | I | R | I | R |
| E11 | γ | S | S | R | S | S | R | I | S |
| E28 | γ | I | R | R | S | I | R | R | R |
| D2 | γ | R | R | R | R | R | R | I | R |
| A17 | γ | I | R | R | I | R | R | I | R |
R:耐药 resistant;I:中度敏感 moderately sensitive;S:敏感 sensitive。 |
表6 乳酸菌抑菌结果Table 6 Antibacterial results of LAB |
| 菌株编号 Strain numbers | 沙门氏菌 Salmonella | 大肠杆菌 Escherichia coli | 金黄色葡萄球菌 Staphylococcus aureus |
|---|---|---|---|
| B1 | ++ | ++ | + |
| B8 | ++ | + | ++ |
| A7 | + | ++ | ++ |
| C24 | + | + | ++ |
| D4 | ++ | ++ | +++ |
| C2 | ++ | ++ | ++++ |
| C16 | + | + | ++ |
| D3 | ++ | ++ | + |
| A16 | + | ++ | ++ |
| C1 | ++ | ++ | +++ |
| D17 | + | ++ | +++ |
| E12 | + | ++ | ++ |
| E11 | + | + | ++ |
| E28 | ++ | ++ | ++++ |
| A17 | + | ++ | ++ |
“+”表示抑菌圈直径为9.00~12.99 mm,“++”表示抑菌圈直径为13.00~16.99 mm,“+++”表示抑菌圈直径为17.00~19.99 mm,“++++”表示抑菌圈直径≥20.00 mm。 | |
“+” indicated antibacterial zone diameter was 9.00 to 12.99 mm, “++” indicated antibacterial zone diameter was 13.00 to 16.99 mm, “+++” indicated antibacterial zone diameter was 17.00 to 19.99 mm, and “++++” indicated antibacterial zone diameter was ≥20.00 mm. |

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