The present study was aimed at isolating Lactobacillus sp. from yoghurt and to determine its bactericidal activity. The strain was identified by using morphological, physiological, staining and biochemical methods. The isolate of LAB was identified as Lactobacillus delbreukii as it showed growth at 45ºC and no growth at 15ºC, was fermentative positive, gram-positive, rod-shaped, non-spore forming, catalase negative etc. Live culture broth were screened for their antibacterial activity. Bactericidal activity was analyzed by agar well diffusion assay against the pathogenic organisms. Pathogenic bacteria such as Bacillus subtilis, Staphylococcus aureus, Klebsiella pneumoniae, Salmonella typhi and E.coli were used as targets. The live culture broth inhibited the growth of a range of gram positive and gram negative microorganisms