Antibacterial activities of the surface microflora of Kefalograviera cheese

The microflora developed on the surface of Kefalograviera, a hard cheese, during ripening in the warm room was studied. The microbial total counts and yeasts decreased (P < 0.05) and the same was observed with the pH on ripening for 15 days. Bacilli dominated at day 4 while at 15 days Micrococcaceae and enterococci occurred frequently. A great number (38 out of 56) of the isolates exhibited narrow spectrum of antibacterial activities against Gram-positive indicator strains, while ten of the Bacillus isolates (Bacillus pumilus) inhibited the growth of Listeria monocytogenes. The extracellular antilisterial substances were sensitive to proteinase K and heat labile (at 100 °C).