Characteristics and Antibacterial Activity of Metabolites from Lactobacillus acidophilus Strains Produced from Novel Culture Media

The search for new culture media that will encourage the growth and production of active antimicrobial metabolites by probiotics has become of utmost importance in the light of increasing bacterial resistance and the high costs of commercial media to cultivate the probiotics. Hence, the study was aimed at characterizing and determining the activity of metabolites obtained from Lactobacillus acidophilus strains cultivated in two novel media against pathogenic bacteria. Eight strains of L. acidophilus were cultivated in Morinda citrifolia juice and Glycine max extract. Bacterial metabolites were harvested and evaluated for antibacterial activity against two human pathogens, Staphylococcus aureus and Escherichia coli. All tested metabolites of L. acidophilus strains showed significant bactericidal activity, as indicated by zone of inhibition in the culture plates compared with control. There was a statistically significant difference in the activity of the metabolites against S. aureus and E. coli. Metabolites of L. acidophilus FTDC-4462 strain exhibited the highest zone of inhibition against S. aureus and E. coli in both growth media. Metabolites of L. acidophilus strains were more effective against S. aureus than E. coli. There were no significant differences in the growth media on antimicrobial effect of the metabolites of L. acidophilus against E. coli and S. aureus. Metabolites of L. acidophilus significantly inhibited the growth of both pathogenic bacteria used and can be used as potential antibiotic or probiotic agents. M. citrifolia juice and G. max extract could be used as novel and cheap culture media for L. acidophilus to produce antibacterial metabolites.