Antibacterial activity of lactobacilli strains isolated from Laban Rayeb “Egyptian traditional fermented milk” against Pseudomonas fluorescens and Escherichia coli in vitro

Document Type : Original Article

Authors

1 Department of Food Hygiene and Control, Faculty of Veterinary Medicine, University of Sadat City, Menoufia, Egypt.

2 Industrial Biotechnology Dept., Genetic Engineering and Biotechnology Research Institute, University of Sadat City, Egypt

3 Department of Food Hygiene & Control, Faculty of Veterinary Medicine, University of Sadat City, Egypt

Abstract

Lactobacilli are significant to dairy industry due to their involvement in the production of several fermented dairy products. The present study was conducted to assess the antibacterial activity of the of lactobacilli strains (Lactobacillus pentosus RMLB1, Lactobacillus acidophilus RMLB9, Lactobacillus plantarum RMLB20, Lactobacillus pentosus RMLB22 and Lactobacillus salivarius RMLB32) isolated from the Egyptian traditional fermented milk “Laban Rayeb”. The lactobacilli strains were evaluated using the agar-well diffusion assay against pathogenic strains of Pseudomonas fluorescens and Escherichia coli. Furthermore, the ability of these strains to adhere to human intestinal mucous was examined. The results indicated that all the LAB strains showed a variable antibacterial activity against P. fluorescens and E. coli. L. acidophilus RMLB9 and L. salivarius RMLB32 showed the highest inhibitory effect against both pathogens. Moreover, all strains adhered in vitro to intestinal mucous with variable extents. The highest adhesive level, compared to the reference strain of Bifidobacterium bifidum, was showed by L. plantarum RMLB20 followed by L. salivarius RMLB32 and L. acidophilus RMLB9. The obtained results highlight that the Egyptian traditional fermented milk “Laban Rayeb” could be a source for potential probiotic bacteria possessing good inhibitory activity against P. fluorescens and E. coli.

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