Antagonism of Lactic Acid Bacteria Against
Selected Pathogenic Bacteria and Spoilage Fungi
Khandakar Md. Rayhanu Kabir, Md. Rafiqul Islam,
Md. Sabir Hossain, Sudip Paul and Md. Ibrahim Khali
Department of Biotechnology and Genetic Engineering,
Islamic University, Kushtia 7003, Bangladesh.
Lactic acid bacteria (LAB) have been studied for many years to be used as biopreservative due to
production of various antimicrobial compounds. This study was carried out for the determination of natural
antimicrobial activity of LAB isolated from curd samples. LAB were screened for antagonistic activity
against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus and Bacillus subtilis.
The inhibitory activity was determined by a disc diffusion method. Strong (+++) and moderate (++) inhibition
were found for E. coli and weak (+) inhibition was found for S. aureus. No zone of inhibition was found for
B. subtilis. Studies were made to compare the production of antibiotic components by LAB in different nutrient
media (LAPT broth with different supplements). The media LAPT with riboflavin (1.5 mg/l) and LAPT with
vitamin B mixture (1.5 mg/l) showed the positive result. LAB were also screened for antagonism against spoilage
fungi isolated from potato samples and showed antifungal activity against Aspergillus niger. This study led
to suggest that food-derived LAB strains could be selected for biotechnological application to control
pathogenic bacteria and spoilage fungi.