Phenotypic characterisation and assessment of the inhibitory potential of Lactobacillus isolates from different sources

Six strains of Lactobacillus spp. were isolated from fermenting corn slurry, fresh cow milk, and the faeces of pig, albino rat, and human infant. Their inhibitory action was tested against some spoilage and pathogenic bacteria. Lactobacillus acidophilus isolated from milk was found to display a higher antagonistic effect with zones of inhibition of 6 and 15 mm against E. coli and Pseudomonas aeruginosa respectively. This isolate was incapable of inhibiting the other indicator bacteria. The other isolates have zones of inhibition ranging between 1 to 4 mm. Characterisation of the microbial metabolic product for antimicrobial agents reveals that lactic acid may be responsible for the inhibition of the indicator organisms.