ISOLATION, SCREENING AND IDENTIFICATION OF LACTIC-ACID BACTERIA FROM TRADITIONAL FOOD FERMENTATION PROCESSES AND CULTURE COLLECTIONS

This study describes a search for lactic acid bacteria capable of exo-polysaccharide production or exhibiting antimicrobial or proteolytic activities. About 400 lactic acid bacteria were isolated from traditional fermented foods (sour dough, sausages, table olives, cheese and other dairy products). Together with almost 200 lactic acid bacterial strains obtained from culture collections, these strains were screened for exo-polysaccharide production, bacteriocin production and proteolytic activity. Thirty strains producing exopolysaccharide (EPS) and 8 Lactococcus lactis strains producing a nisin-like bacteriocin were selected. The proteolytic activities of all strains were determined, using a test based on the degradation of casein. As a result a division was made into 4 groups with increasing proteolytic activities. Among the EPS-producing strains, 14 were isolated from various olives fermentations, all identified as Lactobacillus paracasei. EPS-producing strains isolated from Belgian salami were characterized as being closely related to Lactobacillus sake and were therefore referred to as Lactobacillus sake-like. Another 10 EPS-producing strains were obtained from culture collections.