Identification of lactic acid bacteria isolated from Genestoso cheese throughout ripening and study of their antimicrobial activity

The aim of this work was to study the antimicrobial activity of 395 strains of lactic acid bacteria isolated from Genestoso cheese throughout manufacture and ripening. These were: Lactobacillus (137 strains), Lactococcus (125 strains), Leuconostoc (58 strains) and Enterococcus (75 strains). After the extract had been neutralized and treated with catalase to exclude the action of hydrogen peroxide, 13 lactococci, three lactobacilli, three leuconostocs and five enterococci continued to show antimicrobial activity against one or more of the reference varieties used as indicator strains (Enterococcus faecalis CECT 481, Staphylococcus aureus CECT 240, Lactobacillus plantarum CECT 748, Clostridium tyrobutyricum CECT 4011 and Listeria monocytogenes CECT 4031). The 24 strains of lactic acid bacteria showing antimicrobial activity after excluding the action of hydrogen peroxide were identified at species level by genetic methods. The majority of these strains were isolated from the batch ripened in autumn (37.5% of strains) and the batch ripened in spring (29.2% of 15 strains) manufactured by the same cheesemaker and mainly during manufacture and the first days of ripening.