DNA fingerprinting methods used for identification of yeasts isolated from sicilian sourdoughs

The nature of sourdough yeast microflora was investigated. Samples were collected from different bakeries that do not use starter cultures, but rely on the traditional art of bread making. Pulsed field gel electrophoresis (PFGE), PCR/RFLP of the Non-Transcribed Spacer 2 (NTS2), the inter δ regions and the Internal Transcribed Spacer (ITS) of the ribosomal DNA (rDNA) and partial sequencing of the 26S rDNA were used to identify and differentiate the yeast cultures isolated. In particular, PCR/RFLP of the ITS region, with restriction enzyme Hae III made it possible to differentiate Candida milleri from Candida humilis. A high degree of polymorphism was observed in the inter-δ regions of the strains belonging to the S. cerevisiae, species; contrary to what has been mentioned in literature, strains with the same profile are not necessarily identical. Saccharymyces cerevisiae, Saccharomyces cerevisiae old type anamensis, Issatchenkia orientalis, Candida milleri and Candida humilis were found to be the predominant species in Sicilian sourdough.