Evaluation of antimicrobial properties and their substances against pathogenic bacteria in-vitro by probiotic Lactobacilli strains isolated from commercial yoghurt

Abstract

Milk and milk products have been used by human population since ancient ages and have been a well known source of Lactobacilli. The beneficial effects of viable probiotic bacteria as dietary supplements have gained huge research interest, Lactobacillus spp. with probiotic characteristics are widely used to prepare fermented dairy products such as yoghurts, milk-shakes etc. The goal of the present study was to examine Lactobacillus species with potential activities, total four different companies of Yoghurt samples were collected from City market of Gulbarga region for isolation of probiotic Lactobacillus species. Among the samples, 32 lactic acid bacteria strains were isolated, thirteen (13/32) best Lactobacillus isolates were selected by preliminary screening as potential probiotics with antimicrobial activity against pathogenic bacteria. All the Lactobacillus isolates were then characterized in vitro for their probiotic characteristics and antimicrobial activities against pathogens. The isolates were resistant to NaCl (1–6%), bile salt (0.5–3%) and showed good growth in the acidic condition, while maximum growth was observed at pH around 6.0. All the isolates were susceptible to clinical antibiotics; also the isolates were exhibited effective aggregation and hydrophobicity studies. Based on the results, selected Lactobacillus isolates were considered as novel and potential probiotic bacteria. Thus, further extensive research on isolation and characterization of probiotic bacteria from local dairy products and their growth optimization might be necessity for development of probiotic enriched food supplement and human health benefits through prevention and controlling of bacterial infections. Keywords: Lactic acid bacteria, Lactobacilli, Yoghurt, Antimicrobial activity and dairy products, Bacteriocin