In Vitro Evaluation of the Broad-Spectrum Antimicrobial Potential of Lactic Acid Bacteria Isolated from Milk Whey and Nunu for Veterinary Applications

Abstract

Background Information One of the characteristic of bacteria zoonoses diseases is their tendency to re-emerge, as such they said to be responsible for a very high proportion of morbidity and mortality. Many documented zoonotic diseases and reported to be resistant to some conventional antibiotics. Similarly challenging is the fact that most of the antibiotics currently being used against these diseases are reported not to be completely metabolized and are often released in unmetabolized forms which when they find their ways into the food chain becomes health issue. Metabolites from some Lactic Acid Bacteria are being harnessed as a bio-active compounds for the novel unconventional control of these diseases which this research seeks to make contribution. Abstract Zoonoses incidences continue to play significant roles in both human and veterinary medicine and their eradication especially in the developing country like Nigeria, is difficult. Zoonotic food-borne infections caused by Gram-positive and Gram-negative bacteria are re-emerging. Several findings indicated that the cell-free supernatant derived from some Lactic Acid Bacteria have some antibacterial effects when applied directly or added to food during packaging. The aim of this study was to investigate the in vitro antagonistic effect of cell-free supernatant derived from some LAB species isolated from whey and Nunu (obtained from a locally fermented milk product) against some zoonotic bacteria pathogens (Escherichia coli, Salmonella sp. and Staphylococcus aureus. Streptococcus sp. and Salmonella sp. Four (4) LAB isolates were isolated, identified using basic morphological and biochemical characterization and screened on the basis of functional and technological characterization. The Cell-free supernatant from these strains, Lactobacillus casei LB01, Lactobacillus sp. LB02, Lactobacillus acidophilus LB03 and Lactobacillus plantarum LB04 were prepared by centrifugation at 10,000 rpm for 5 minutes and used against the indicator organisms at 107 CFU/ml using agar well diffusion method. The cell-free supernatant inhibited the growth of both Gram- positive and Gram-negative bacteria strains of veterinary origins. Our findings suggest that the LAB strains have the potential for antibiotic alternatives for the control of several zoonotic diseases. This holds a great advantage in the current efforts to tackling and reducing the prevalence and spread of zoonotic diseases which are re-emerging in Nigeria