Diversity and technological potential of lactic acid bacteria of wheat flours

Lactic acid bacteria (LAB) were analysed from wheat flours used in traditional bread making throughoutSicily (southern Italy). Plate counts, carried out in three different media commonly used to detect foodand sourdough LAB, revealed a maximal LAB concentration of approximately 4.75 Log CFU g 1. Coloniesrepresenting various morphological appearances were isolated and differentiated based on phenotypiccharacteristics and genetic analysis by randomly amplified polymorphic DNA (RAPD)-PCR. Fifty uniquestrains were identified. Analysis by 16S rRNA gene sequencing grouped the strains into 11 LAB species,which belonged to six genera: Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Pediococcus andWeissella. Weissella cibaria, Lactobacillus plantarum, Leuconostoc pseudomesenteroides and Leuconostoccitreum were the most prevalent species. The strains were not geographically related. Denaturinggradient gel electrophoresis (DGGE) analysis of total DNA of flour was used to provide a more completeunderstanding of the LAB population; it confirmed the presence of species identified with the culturedependentapproach, but did not reveal the presence of any additional LAB species. Finally, the technologicalcharacteristics (acidifying capacity, antimicrobial production, proteolytic activity, organic acid,and volatile organic compound generation) of the 50 LAB strains were investigated. Eleven strains wereselected for future in situ applications.