巴马地区产胞外多糖益生乳酸菌的筛选及鉴定

Screening and identification of extracellular polysaccharides-producing probiotic lactic acid bacteria from Bama region

采用含碳酸钙的快速初筛培养基,结合形态学观察、革兰氏染色、过氧化氢酶接触实验、菌落拉丝法和硫酸-苯酚法,从巴马自然发酵食品中筛选产胞外多糖乳酸菌,对其耐酸、耐胆盐、细胞表面疏水性和生物安全性进行研究,并采用分子生物学技术对筛选益生菌株进行鉴定。结果表明,从巴马自然发酵食品中筛选到6株产胞外多糖乳酸菌,编号分别为R2、R3、R4、R5、R6和R9;其中菌株R6多糖产量最高(106.73 mg/L),p H 3时耐酸性最佳,0.05%胆盐时延滞期最短(1.50 h),细胞表面疏水性最突出(在十六烷中的细胞表面疏水性达到了93.28%),对沙门氏菌、大肠杆菌和金黄色葡萄球菌的抑制作用最显著,且对多种常见抗生素敏感和不具有溶血活性,菌株R6被鉴定为植物乳杆菌(Lactiplantibacillus plantarum),可作为潜在益生菌株。

Using a rapid initial screening medium containing calcium carbonate,combined with morphological observation,Gram staining,catalase contact experiment,colony drawing method,and sulfuric acid phenol method,the extracellular polysaccharide-producing lactic acid bacteria were screened from Bama natural fermented food,and the acid and bile salt resistance,cell surface hydrophobicity,and biological safety were studied,and the screened probiotic was identified by molecular biological technique.The results showed that 6 strains of extracellular polysaccharide-producing lactic acid bacteria were screened from Bama naturally fermented food,and numbered as R2,R3,R4,R5,R6 and R9,respectively.Among them,the strain R6 had the highest polysaccharide production(106.73 mg/L),the acid resistance was optimal at pH 3,the shortest delay time(1.50 h)at bile salt concentration of 0.05%,and the most prominent cell surface hydrophobicity(cell surface hydrophobicity in hexadecane reached 93.28%).The strain R6 had the most significant inhibitory effect on Salmonella,Escherichia coli,and Staphylococcus aureus,which was sensitive to various common antibiotics and had no hemolytic activity.The strain R6 was identified as Lactiplantibacillus plantarum,which could serve as a potential probiotic strain.