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ANTONIO ALFONZO

Combined approach for the investigation of dominant fermenting microbiota in two traditional sourdoughs produced in sicily

  • Autori: Gaglio, R.; Alfonzo, A.; Francesca, N.
  • Anno di pubblicazione: 2017
  • Tipologia: Articolo in rivista (Articolo in rivista)
  • Parole Chiave: Lactic acid bacteria; Multiplex-PCR; Sourdough; Yeast; Food Science
  • OA Link: http://hdl.handle.net/10447/281950

Abstract

In order to explore the community of lactic acid bacteria (LAB) and yeasts present in two major typical Sicilian sourdoughs, seven mature sourdoughs for "Pane Nero di Castelvetrano" (CV1 - CV3 samples) and "Pane di Monreale" (MR1 - MR4 samples) were analysed through a culturedependent and culture-independent approach. The highest values of microbial counts were revealed in MR1 sourdough. In particular, LAB counts were at about 109 CFU/g in media specific for typical sourdough LAB, such as SDB and SFM, while levels of 106 CFU/g were registered for yeasts. The total DNA form each sourdough sample was extracted and subjected to a multiplex-PCR in order to recognize the major groups of LAB. Seventy-six LAB with a rod shape, presumptively Lactobacillus, were phenotypically grouped and subjected to a genotypic identification by sequencing of the 16S rRNA gene and further confirmed by species-specific PCRs. Yeasts were isolated and identified by a combined genotypic approach consisting of restriction fragment length polymorphism (RFLP) of 5.8S rRNA gene and sequencing of D1/D2 domain of the 26S rRNA gene. The LAB species identified were Lactobacillus sanfranciscensis, Lactobacillus paralimentarius, Lactobacillus brevis and Lactobacillus coryniformis. Among yeasts, Saccharomyces cerevisiae, Pichia guiliermondii, Pichia segobiensis, Rhodotorula acuta and Rhodotorula mucilaginosa were the species hosted in Sicilian sourdough. The multiplex PCR carried out on total DNA of sourdoughs allowed the rapid identification of the majority of sourdough lactobacilli but the culture-dependent methodology was confirmed to be necessary for the detection of the species, such as Lactobacillus coryniformis not included in the system.