Ability of Chosen Lactic Acid Bacteria to Produce Antibacterial Substances

Blaženka Brkić, Jagoda Šušković, S. Matošić and Krešimir Gjuračić*

Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottiieva 6, 10000 Zagreb, Croatia
*Pliva Research Institute, Laboratory or Molecular Biology, Prilaz baruna Filipovića 89,10000 Zagreb, Croatia

Article history:
Received October 11, 1995 
Accepted December 6, 1995

Summary:
Six strains of lactic acid bacteria isolated from silage, fermented milk and vegetables, were examined for antagonistic activities against entheropathogenic microorganisms and lactic acid bacteria. The two screening methods used were the agar spot test and the disc assay method. Cell-free supernatants of lactic acid bacteria inhibited the growth of Staphylococcus aureus 3048, Staphylococcus aureus K-144, Salmonella mumum, Escherichia coli, Bacillus cereus and Bacillus subtilis. However, concentrated and neutralized supernatants from four of the six strains (Lactobacillus acidophilus, Lactobacillus plantarum L4, Lactobacillus plantarum Z88, Enterococcus faecium) showed antibacterial activity against Gram-negative and Gram-positive target strains, as well as same strains of lactic acid bacteria. These results confirmed the presence of antibacterial substances other than lactic acid. Furthermore, plasmids had been isolated front these four lactic acid bacteria which exhibited higher antibacterial activity.