CONICET | Buscador de Institutos y Recursos Humanos

Lactic acid bacteria are part of the human diet for millennia through fermented foods. They have the GRAS character (generally regarded as safe) and they are used to improve the technological and nutritional properties of several food products. The aim of this study was to conduct enrichment, isolation and selection of potential lactic acid bacteria from different seeds and grains and to evaluate some technological properties. This will allow the construction of an ICYTAC bacteria strains bank. We worked with the following raw material: wheat (varieties: Klein Taurus, Klein Tiger, 3004, Esmeralda), Oats, Rye, Triticale, Barley, Chia, Sesame, Sorghum (varieties White Argensor, High Tannin Malon, Low Tannin Paisano). Enrichment was performed in appropriate media (MRS modified (MRS + maltose 1%) and LAPTg for 48 h at 30 ° C, pH of enrichment culture was determined and colonies were counted in agarized media. Colonies with different morphotypes were selected and are propagated in the corresponding medium. Gram staining and catalase test was performed. Acidification activity was further determined in sterile flour extract liquid broth. Inhibitory activity was assayed by the agar diffusion method using as indicator, among others, strains Staphylococcus aureus, Escherichia coli, Listeria innocua and Lactobacillus sp. Counts from 6.6 to 9 log CFU (colony forming units) from the different samples were obtained. There were 200 strains isolated and conserved. A group of 50 strains was selected by Gram positive staining, catalase negative and morphology of cocci or bacilli. Most acidifying ability was observed with ES124, ES142 and ES148 strains that reduce the pH of the medium (initial pH: 6) to 3.3, 3.26 and 3.27 respectively. 6 strains present antimicrobial activity against Listeria innocua. Next steps are identification by molecular techniques of the selected strains and further search for technological properties or beneficial effects on human health