A polyphasic study on the taxonomic position of industrial sour dough yeasts

The sour dough bread making process is extensively used to produce wholesom e palatable rye bread. The process is traditionally done using a back-slopp ing procedure. Traditional sour doughs in Finland comprise of lactic acid b acteria and yeasts. The yeasts present in these doughs have been enriched i n the doughs due to their metabolic activities, e;g. acid tolerance. We cha racterized the yeasts in five major sour bread bakeries in Finland. We foun d that most of the commercial sour doughs contained yeasts which were simil ar to Candida milleri on the basis of 18S rDNA and EF-3 PCR-RFLP patterns a nd metabolic activities. Some of the bakery yeasts exhibited extensive kary otype polymorphism. The minimum growth temperature was 8 degrees C for C. m illeri and also for most of sour dough yeasts.