Identification of yeasts from sourdoughs


TITOLO: Comparison of cultural methods for the identification and molecular investigation on yeasts from sourdoughs for Italian sweet baked products

RIVISTA: FEMS Yeast Research

NUMERO RIVISTA: n. 4, p. 609-618

Twenty five yeast strains isolated from sourdough samples for Panettone, Pandoro and Cornetto brioche manufactured by eight different bakeries in northern Italy were characterised. Classification was performed by the Simplified Identification Method (SIM), Kurtzman and Fell’s identification protocol, API system from BioMérieux (France) and MicroLog™ system from Biolog (U.S.A). Genetic diversity was investigated by Randomly Amplified Polymorphic DNA fingerprinting and mitochondrial DNA restriction enzyme analysis. Sequences of the internal transcribed spacers between 18S and 26S rDNA genes were analysed. Candida humilis was the predominant species (56% of isolates), whereas the remaining strains (44%) were related to the Saccharomyces cerevisiae sensu stricto group. Identification systems based on phenotypic analysis proved to be unreliable to identify yeasts from sourdough. Either RAPD PCR or mt DNA restriction analysis showed to be suitable for the identification of species, but could not be used to differentiate among the isolates at strain level. Sequencing of the ITS region permitted a consistent classification of the sourdough yeasts.

AUTORI: Foschino R., Gallina S., Andrighetto C., Rossetti L., Galli A.