Antimicrobial activity of lactic acid bacteria isolated from locally fermented cow milk products sold in Keffi, Nigeria on clinical bacteria

Lactic acid bacteria (LAB) are renowned for the potential of producing antimicrobial compounds. This study focuses on isolation and antimicrobial effect of lactic acid bacteria isolated from locally fermented cow milk products (Nono, Kindirmo and Maishanu). The antimicrobial effect of the LAB isolates against clinical test isolates was also investigated. Fifty (50) samples each of Nono and Kindirmo, and twenty-five (25) of Maishanu were collected from cow milk products sellers in Keffi, Nasarawa State Nigeria. Standard microbiological methods were used for the isolation and identification of Lactic acid bacteria from fermented cow milk products. The percentage isolation rate of Lactobacillus species from Nono and Kindirmo showed that 52.0% were isolated from Nono and 58.0% from kindirmo. The highest percentage occurring Lactobacillus species from Nono was Lactobacillus plantarum (14.0%) and the highest percentage occurring Lactobacillus species from kindirmo was Lactobacillus delbrueckii (16.0%). The Lactobacillus species isolated were screened for antibacterial activity and it was observed that seven (7) were able to show inhibition zones. The antimicrobial effect of the LAB culture supernatant against clinical isolates of Staphylococcus aureus, Escherichia coli and Shigella dysenteriae was investigated using agar diffusion technique. The highest 22.00mm was observed by Lactobacillus delbrueckii and Lactobacillus delbrueckii against Shigella dysenteriae, while the least inhibition zone of 15.00mm was observed by Lactobacillus delbrueckii and Lactobacillus acidophilus against E. coli. In conclusion, the zones of inhibition observed in this research strongly suggest that various antimicrobial compounds (lactic acid, acetic acid, propionic acid and bacteriocins) produced during the fermentation process are potent in the control of growth of the test bacteria.