一株高产胞外多糖的乳酸芽孢杆菌的筛选及功能鉴定

Screening and functional identification of a Lactobacillus strain with high exopolysaccharide production

摘要:

为丰富可用于功能食品的微生物资源,本研究从四川怀远发酵米糕作坊环境中分离出1株高产胞外多糖和乳酸的芽孢杆菌（XQ），经分子鉴定为短小芽孢杆菌Bacillus pumilus.HPLC检测XQ产乳酸含量为8 mg/mL；苯酚硫酸法检测粗胞外多糖浓度达到7.16 mg/mL.并经滤纸片法测定出XQ产生的粗胞外多糖对常见的食源性病原菌沙门氏菌、金黄色葡萄球菌、大肠杆菌均有抑菌作用.DEAE分离粗胞外多糖为中性多糖E1和酸性多糖E2.当浓度为10 mg/mL时，E1对羟自由基清除活性为3.24%，而E2羟自由基清除活性高达84.58%；E1和E2对DPPH自由基的清除活性分别为26.07%和47.03%.E2还具有明显的抗肿瘤活性：当浓度为4 mg/mL时，E2对A549细胞的生长抑制率可达到81.30%，在浓度为6 mg/mL时，E2对HepG2细胞的生长抑制率为53.40%.在模拟胃肠道耐受性实验中发现XQ对胰蛋白酶、胃蛋白酶和胆盐均具有良好的耐受性.在安全性方面，没有发现XQ有溶血现象，对革兰氏阳性菌抗生素没有抗药性，具有良好的药物安全性.表明XQ可作为一种潜在的益生菌.

Abstract:

In order to enrich the microbial resources that can be used in functional foods, a Bacillus (XQ) strain with high production of extracellular polysaccharide and lactic acid was isolated from the fermented rice cake workshop in Huaiyuan, Sichuan，and it was identified as Bacillus pumilus. The lactic acid content detected by HPLC was 8 mg/mL and the concentration of crude exopolysaccharide detected by the phenol-sulfuric acid method was 7.16 mg/mL. It was determined by the filter paper method that the extracellular polysaccharides and fermentation broth had inhibitory effects on common foodborne pathogens Salmonella, Staphylococcus aureus, and Escherichia coli. The extracellular polysaccharide was further separated to obtain neutral polysaccharides E1 and acidic polysaccharides E2. When the concentration was 10 mg/mL, the scavenging activity of E1 on hydroxyl radicals was 3.24%, while the scavenging activity of hydroxyl radicals of E2 was as high as 84.58%; the scavenging activities of E1 and E2 on DPPH free radicals were 26.07% and 47.03%, respectively. E2 also had obvious anti-tumor activity. When the concentration was 4 mg/mL, the growth inhibition rate of E2 on A549 cells could reach 81.30%, and when the concentration was 6 mg/mL, the growth inhibition rate of E2 on HepG2 cells was 53.40%. In the simulated gastrointestinal tolerance experiments, it was found that XQ has a high tolerance to trypsin, pepsin and bile salts. In terms of safety, XQ has not been found to have hemolysis, is not resistant to Gram-positive antibiotics, and has good drug safety. In summary, this study indicated that XQ can be used as a potential probiotic.