Exploring the Benefits: Lactobacilli versus pln Gene Isolated from Persian Marinated Olives

Abstract

Microbe-assisted therapy using probiotic lactic acid bacteria (LAB) is a promising field of research. This study investigated the probiotic properties of Lactobacillus plantarum strains isolated from various Persian Marinated olives. LAB strains were isolated from three Iranian olive cultivars on MRS agar plates. After biochemical and molecular identification, probiotic properties of L. plantarum isolates were evaluated, including bile and antibiotic resistance and antimicrobial activity against Escherichia coli PTCC1399, Shigella dysenteriae PTCC1188, and Salmonella typhimurium PTCC1639. Antimicrobial activity was assessed using well diffusion, disc diffusion, and spot-on-lawn assays. The mean diameter of inhibition zones was compared using one-way ANOVA. The presence of the pln gene was investigated by PCR. Out of 45 olive cultivars studied, 36 LAB species were isolated. Of these, 20 (55.5%) were L. plantarum, 9 (25%) L. casei, 5 (14%) L. brevis, and 2 (5.5%) L. acidophilus. Except for L. acidophilus, which grew at pH 3, other Lactobacillus species did not grow at pH 2 and 3. Among the isolates, 81% were resistant or highly resistant to bile salts. In PCR, eight isolates produced a specific band with L. plantarum-specific primers. The results showed the antimicrobial activity of L. plantarum isolated from Iranian olives against E. coli, S. dysenteriae, and S. typhimurium. The pln gene band was observed at 1520 bp in L. plantarum isolates. The study showed that 8 L. plantarum isolates possessed the pln gene. Bacteria with the pln gene can hydrolyze bile salts, which benefits both the bacteria and the host, such as bile detoxification against bacteria, bacterial colony formation in the intestine, and reducing serum cholesterol in the host. Considering the probiotic properties of L. plantarum strains isolated from Iranian olives, their use as a preventive and therapeutic measure against infectious bacteria.