A Study on the Antibacterial Activity of Lactic Acid Bacteria Isolated from Traditional Iranian Milk Samples

Abstract

198 Lactic acid bacteria (LAB) were isolated from Iranian milk samples. Almost all isolated<br />LAB showed inhibitory activity towards E. coli and S. aureus as Gram negative and Gram<br />positive indicators, respectively. No role was observed for hydrogen peroxide in the activity of<br />all isolated strains while organic acids proved a prominent role in all detected inhibitory<br />activities. Within isolated LAB, four strains represented the inhibitory activity against S. aureus<br />based on the production of bacteriocin-like inhibitory substances (BLIS). Inactivation of the<br />activity by proteolytic enzymes demonstrated the proteinaceous nature of the antimicrobial<br />compounds. The selected producers were identified as L. lactis, E. faecium 1, E. hirae and E.<br />faecium 2 based on biochemical tests according to Bergy's manual of systematic bacteriology.<br />L. lactis had the highest Minimum Inhibitory Concentration (320 IU/ml) and showed<br />bacteriostatic mode of activity towards the indicator bacteria.