Differentiation
of yeast isolates from Polish brewery by PCR-RFLP of rDNA.
Wojciech Barszczewski (1), Malgorzata Robak (2)
(1) Kat. Biotechnologii i Mikrobiologii Zywnosci, AR Wroclaw, Norwida 25,
50-375 Wroclaw, Poland (barszcz3@wp.pl); (2) (mrob@ozi.ar.wroc.pl)
The application of yeast starters became essential in the production of fermented foods and beverages since 1883, when Emil Christian Hansen first used a pure culture of brewer's yeast on a large scale. Unfortunately, yeasts are invading microorganisms also, and the growth of wild strains could lead to many failures in the fermentation processes or in final product. For these reasons the detection of contaminating yeast became a necessity of guaranty of high beer quality. The aim of this work was to differentiate and identified wild yeast isolates during the beer production process in Polish lager breweries by the application of PCR-RFLP of rDNA with NS3 and ITS4 as primers and MspI, HaeIII and ScrFI as restriction enzymes. Nineteen yeast strains isolated from pitching yeast, tanks or from non-pasteurised final beer and thirty type strains were studied. Digestion of amplified region with MspI, HaeIII and ScrFI allowed the separation of nineteen wild isolates into 10, 12 and 11 groups respectively and three of isolates were identified as the starter strain. However, in our study three endonucleases commonly used in restriction analysis of fungal rDNA did not allow the differentiation between all tested strains, the differentiation between production strain and other isolated yeasts were evident. Hence, the chosen PCR-RFLP of rDNA methodology could be directly applied in this brewing company.