Phenotypic and molecular identification and clustering of lactic acid bacteria and yeasts from wheat (species Triticum durum and Triticum aestivum) sourdoughs of Southern Italy

The microflora of 25 wheat sourdoughs from the Apulia region. Southern Ital y, was characterized. The sourdoughs were mainly produced from Triticum dur um wheat. The number of lactic acid bacteria and yeasts ranged from ca. log 7.5 to log 9.3 colony forming units (cfu)/g and from lot: 5.5 to log 8.4 c fu/g, respectively. About 38% of the 317 isolates of lactic acid bacteria w ere identified by conventional physiological and biochemical tests. Phenoty pic identification was confirmed by 16S rDNA acid 16S/23S rRNA spacer regio n PCR. Overall, 30% of the isolates were identified as Lactobacillus sanfra nciscensis, 20% as Lb. alimentatius 14% as Lb. brevis, 12% as Leuconostoc c itreum, 7% as Lb. plantarum, 6% as Lactococcus lactis subsp. lactis, 4% as Lb. fermentum and Lb. acidophilus, 2% as Weissella confusa and 1% as Lb. de lbrueckii subsp, delbrueckii. Some of these species have not been previousl y isolated from sourdoughs. Since bakers yeast is widely used in sourdough production, Saccharomyces cerevisiae was largely found. The phenotypical re lationships within the main lactic acid bacteria identified were establishe d by using cluster analysis. A microbial map of the 25 sourdoughs was plott ed showing characteristic associations among lactic acid bacteria and diffe rences in the lactic acid bacteria species which were mainly due to the spe cies of wheat flour, use of bakers yeast and type of bread. (C) 2001 Elsevi er Science B.V. All rights reserved.