ACID-BILE TOLERANCE AND ANTIMICROBIAL PROPERTIES OF SOME LACTOBACILLUS SPECIES ISOLATED FROM FERMENTED MILK PRODUCTS

ABTSRACT

Acid-bile tolerance and antibacterial properties of some Lactobacillus species were studied. Milk products (Nunu, Fan milk and Yoghurt) were plated on De-Mann Rogosa Sharpe (MRS) agar and incubated for 24 hours. The Lactobacillus species isolated were L. acidophilus, L. bulgaricus, L. casei and L. plantarum with the occurrence range of (100%), (66%), (33%) and (33.3%) respectively. The Lactobacillus isolates were analyzed for their antimicrobial activity against some test pathogenic organisms such as Staphylococcus sp, Pseudomonas sp, Escherichia coli, Candida sp and Aspergillus sp. Antimicrobial activity of Lactobacillus isolates against the test organisms mentioned earlier ranged from 12.33 ± 1.15mm to 21.00 ± 2.00mm for Lactobacillus acidophilus, 11.69 ± 1.15mm to 12.67 ± 0.58mm for L. bulgaricus, 10.67 ± 1.15mm to 22.67 ± 1.15mm for L. casei and 9.67 ± 1.15mm to 15.67 ± 1.15mm for L. plantarum. This result showed L. bulgaricus to be least active against Pseudomonas sp with inhibition zone of 8.67 ± 0.58mm while L. casei showed the highest activity against Aspergillus sp. The acid-bile tolerance ability of the different Lactobacillus isolates was tested and the results show varying levels of the ability of the isolates to thrive in acid and bile environment.