Isolation and Characterization of Lactobacillus bulgaricus and Lactobacillus casei from Various Foods

摘要

The aim of this study was to determine Lactobacillus bulgaricus and Lactobacillus casei isolated from yoghurt, different kinds of cheese and a traditional food named 'tarhana' (a fermented food made of a mixture of cereal, yoghurt and thyme), and to determine the antimicrobial activity and antibiotic resistance of these isolates. The identity of the culture was based on characteristics of the strains of Lactobacillus spp. as presented in Bergey's Manual of Determinative Bacteriology, carrying out microscopy (morphology), Gram straining, growth at 15 and 45 °C, and fermentation of different carbon sources and growth in 7.5% NaCl. On the basis of all of the identification tests one strain isolated from the cheese was identified as Lactobacillus casei, and the other strain isolated from the probiotic dairy product was identified as L. bulgaricus. The L. casei isolate was resistant to all of the antibiotic discs used in this study. Culture supernatants obtained from the 2 isolates of Lactobacillus spp. exhibited varying degrees of inhibitory activity against strains of Escherichia coli, Staphylococcus aureus, Pseudomonas aeroginosa, Bacillus subtilis, Klebsiella pneumonia, Salmonella typhimurium, and Enterobacter cloacae.