Non starter lactobacilli in Argentinean cheeses

BUDE UGARTE, M.; GUGLIELMOTTI, D.; REINHEIMER, J.; GIRAFFA, G.; HYNES, E.

Nantes, Francia

Congreso; 13th World Congress of Food Science & Technology (IUFoST); 2006

Non-starter lactic acid bacteria isolated from Argentinean cheeses were identified and characterised by focusing on their resistance to biological barriers and their potential as probiotic organisms. Lactobacilli were enumerated and isolated from semi-hard and soft cheeses made with multistrain Streptococcus thermophilus starters. Lactobacilli counts in one week-old cheeses were between 105 – 107 CFU g-1 in all one-month samples, while streptococci were always above 109 CFU g-1. A final number of 22 lactobacilli isolates were retained, identified and their biological and probiotic characteristics were assessed by in vitro tests. Species identity was determined by carbohydrate metabolism and species-specific PCR assays. Genetic diversity was explored by RAPD-PCR analysis. The strains were assigned to the species Lactobacillus casei, L. plantarum, L. rhamnosus, L. curvatus, L. fermentum and L. perolens. All the studied strains tolerated 25 ppm of lysozyme, and most of them showed resistance to 0.3% bile. After incubation in gastric solution (pH 2.0), counts decreased in several log orders, ranging from 3.2 to 7.0. The strains were able to grow in the presence of bile salts, but only three strains were capable of deconjugation. The assayed non-starter lactobacilli fermented prebiotics substrates (specially lactulose and inuline). Some strains showed high cell hydrophobicity and ß-galactosidase activity, as well as inhibitory activity against pathogenic bacteria. We conclude that an importan proportion of the strains presented interesting biological features, which uphold new studies of these organisms as potential probiotics.