Metagenetic Analysis for Microbial Characterization of Focaccia Doughs Obtained by Using Two Different Starters

Lactic acid bacteria (LAB) decisively influence the technological, nutritional, organolepticand preservation properties of bakery products. Therefore, their use has long been considered anexcellent strategy to improve the characteristics of those goods. The aim of this study was theevaluation of microbial diversity in different doughs used for the production of a typical Apulianflatbread, named focaccia. Leavening of the analyzed doughs was obtained with baker's yeast orby applying an innovative "yeast-free" protocol based on a liquid sourdough obtained by usingLeuconostoc citreum strain C2.27 as a starter. The microbial populations of the doughs were studied byboth a culture-dependent approach and metagenetic analyses. The flours used for dough preparationwere also subjected to the same analyses. The metagenetic analyses were performed by sequencing theV5-V6 hypervariable regions of the 16S rRNA gene and the V9 hypervariable region of the 18S rRNAgene. The results indicate that these hypervariable regions were suitable for studying the microbiotaof doughs, highlighting a significant difference between the microbial community of focaccia doughwith baker's yeast and that of the dough inoculated with the bacterial starter. In particular, the doughmade with baker's yeast contained a microbiota with a high abundance of Proteobacteria (82% ofthe bacterial population), known to be negatively correlated with the biochemical properties of thedoughs, while the Proteobacteria in dough produced with the L. citreum starter were about 43.5% lowerthan those in flour and dough prepared using baker's yeast. Moreover, the results show that theL. citreum C2.27 starter was able to dominate the microbial environment and also reveal the absenceof the genus Saccharomyces in the dough used for the production of the "yeast-free" focaccia. Thisresult is particularly important because it highlights the suitability of the starter strain for obtainingan innovative "yeast-free" product.