Isolation and characterization of Lactobacillus species from head Cabbage (Brassica oleracea var. capitate) and its potential application as a probiotic agent

Abstract

Lactic acid bacteria (LAB) are one of the most important groups of microorganisms used in food fermentation, contribute to extended shelf life of the fermented products, and are routinely employed as starter cultures in the manufacture of dairy, meat, vegetable and bakery products. The purpose of this study was to isolate and characterize Lactobacillus species from head cabbage (Brassica oleracea var. capitate) and to evaluate their probiotic properties under conditions simulating human gastrointestinal (GI) tract. For this purpose, a total of 15 head cabbage samples were collected randomly from Haramaya district during the period from May to August, 2014. Based on cultural and biochemical characteristics, Lactobacillus salivarius, Lactobacillus fermentum, Lactobacillus plantarum, Lactobacillus cellobiosus, and Lactobacillus brevis were isolated from the cabbage heads. The probiotic effect of each isolate was evaluated for antimicrobial activity against human pathogenic bacteria, resistance to bile acids, resistance to low pH, antibiotic resistance, and haemolytic activity. Results showed that all isolates had antagonistic effects against pathogenic bacteria (P. aeruginosa, S. aureus, E. coli, and K. pneumonia) with different degree of inhibition zone but L. brevis shown the highest inhibition zone followed by L. cellobiosus and L. plantarum. According to resistance to bile acid, L. plantarum, L. cellobiosus and L. brevis retained their viability with a negligible reduction. Regarding antibiotics resistance, L. plantarum, L. cellobiosus and L. brevis were resistant strains to Streptomycin, Gentamycin, and Tetracycline antibiotics. According to a haemolytic test, all isolates did not exhibit β–haemolytic activity. The growth of Lactobacillus species recorded under all the pH values were viable. In conclusion, the present study indicated that L. brevis and L. cellobiosus possess potential probiotic properties but further in-vivo tests are required to elucidate their particular effects on human health.

Keywords: Antimicrobial susptibility; Gastrointestinal (GI) Tract; Pathogenic Bacteria; Probiotic