Evaluation of probiotic properties and the antibacterial activity of lactic acid bacteria isolated from Rutilus kutum intestine

Lactic acid bacteria are the most common bacteria which have been introduced as probiotic. This study aimed to investigate the impacts of isolated lactic acid bacteria from the Rutilus kutum gut   on Escherichia coli and Pseudomonas aeruginosa. Lactic acid bacteria were isolated from the intestine of 100 fish which are randomly collected from the Caspian Sea and their primary probiotic properties were evaluated based on resistance to acid, bile salts and antibiotics. The inhibitory effect of the bacteria was evaluated on Escherichia coli and Pseudomonas aeruginosa, using the agar disk diffusion method. The specific band was triggered using PCR primers for 16S rRNA gene and validated via sequencing and comparing its sequence with those of gene bank databases. In this case, Lactobacillus acidophilus (54.79%), Lactobacillus plantarum (24.65%), and Lactobacillus brevis (20.54%) were detected. The isolated bacteria were resistant to vancomycin. The most inhibitory effect belonged to Lactobacillus acidophilus sp. on E. coli and P. aeruginosa; with the inhibition zone of 12 and 14 mm, respectively. Lactobacillus plantarum had moderate inhibitory effect on P. aeruginosa while Lactobacillus brevis had neither effect on E. coli nor P. aeruginosa.