Sourdoughs as a source of lactic acid bacteria and yeasts with technological characteristics useful for improved bakery products

In the present research, lactic acid bacteria (LAB) and yeasts which were isolated from sourdough samples were investigated for their technologically useful properties for the production of improved food products. LAB and yeast isolates were cultured and the DNA was extracted; restriction analyses were applied to obtain profile groups and representative strains were sequenced. Lactobacillus sanfranciscensis was the most isolated species followed by Lactobacillus namurensis, Lactobacillus pentosus, Lactobacillus paralimentarius, Lactobacillus sakei, Lactobacillus crustorum, Pediococcus parvulus, Leuconostoc citreum, and Weissella cibaria. Saccharomyces cerevisiae was the most frequently detected yeast species. Minor yeast species were Kazachstania humilis (Candida milleri) and Wickerhamomyces anomalus. The majority of the LAB strains produced CO2; after 4 h of fermentation, the two strains of L. citreum B435 and B521 reached pH values below 5.00, 19 strains reached values below 4.00 after 24 h of fermentation, while after 72 h of fermentation all the strains lowered their pH below 3.60. Two strains, L. citreum B435 and L. sanfranciscensis B450, produced exopolysaccharides. All the LAB strains were able to degrade gluten with different intensity; the strain of L. sakei B433 and the strains of L. pentosus B506, B508, and B512 exhibited the highest intensity of degradation. All the yeast strains were able to grow at a pH value of 2.5. S. cerevisiae L973 and W. anomalus L1081, showed amylolytic properties; excluding the C. milleri L999 all the strains were maltose-positive. According to the technological features, LAB and yeasts strains which are thus isolated are potential starters to be used for improved bakery products.