The selection of sequences of DNA that is intended to amplify by PCR is a critical point of this technique. The
specificity of PCR derives from the precision, with which the initiators perform this task, i.e., hybridize with the
target DNA. For detection of yeast Saccharomyces sensustricto group, the region chosen to be common to most
strains encodes for proteins which are important for this group and has no homology with other micro-organisms.
In Saccharomyces sensu stricto, HO genes have been cloned and sequenced (Kodama et al. 2003). The action
of HO leads to high-efficiency switching between a and a cell types, which occurs by transposition of a block of
information from a genomic storage position to the mating type locus, where this information is expressed and
determines cell type (Russell et al. 1986). In this study, we have developed two new species-specific PCR primer pairs homologous to the HO genes from S. bayanus, S. cerevisiae and S. pastorianus species. Using
these primers, a method is proposed that could quickly and unambiguously identify these species by a simple and
rapid PCR amplification.