Screening and identification of extracellular polysaccharides-producing probiotic lactic acid bacteria from Bama region
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 an-tibiotics and had no hemolytic activity.The strain R6 was identified as Lactiplantibacillus plantarum,which could serve as a potential probiotic strain.
extracellular polysaccharideslactic acid bacteriaisolation and identificationsafety
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