Abstract
In this study, characteristics of bacteriocin like inhibitory substances (BLIS) produced by three strains of Lactobacillus acidophilus (BDLA-1, 2409 and MOLA-2), Lactobacillus fermentum (5174) and Lactobacillus plantarum (2903) were studied. The production of BLIS and its stability during 48 hr of growth was monitored in MRS broth adjusted to pH 5.0, pH 6.0 and in MRS broth supplemented with 1.9% sodium-β-glycerophosphate. The BLIS produced by L. acidophilus (BDLA-1, 2409 and MOLA-2), L. fermentum (5174) and L. plantarum (2903) were active against Lactobacillus delbrueckii ssp. bulgaricus (2519), L. casei (2603), L. helveticus (2700), L. jugurti (2819) and L. acidophilus (MJLA-1). The production of BLIS was greatly affected by the pH of MRS broth and the effect was variable for different bacteria. The BLIS produced by all the bacteria showed activity over a wide range of temperature and pH and were sensitive to proteolytic enzymes, but resistant to lipase, phospholipases and amylases. The activity of BLIS in retentates and permeates of cell free MRS-broth was variable with different bacteria during molecular sieving by ultrafiltration. Two stage fractionation with ammonium sulfate was successful in purifying the BLIS and resulted in a single band on silver staining of SDSPAGE gel for two L. acidophilus strains (BDLA-1 and 2409) and L. fermentum (5174) of the 5 bacteria studied. A band of -54 kDa was common for all of the lactobacilli studied which was in line with the acidophilicin LA-1 reported earlier.
