| Abstract [eng] |
Saccharomyces paradoxus yeast is the philogenetically clossest species for S. cerevisiae. S. cerevisiae and S. paradoxus yeasts both possess LA and M dsRNA viruses. These viruses work as a killer system encoding killer toxins and determining immunity to their own toxins. Mechanisms of action and optimum operating conditions for most of the viruses encoded by S. paradoxus dsRNA are unknown. S. paradoxus yeast cultures (BCR-17-18, CKB-17-33, PR-17-59 and PR-17-63) found on fruits and berries in Lithuania bear dsRNA viruses. S. paradoxus CKB-17-33 yeast culture has a strong killer phenotype. Cultivation in various temperatures (15 °C, 25 °C, 30 °C, 37 °C and 40 °C) and medium pH (pH 3, pH 4, pH 5, pH 6, pH 7, pH 8) showed that killer phenotype and dsRNA maintenance in S. paradoxus CKB-17-33 was unstable. In most cases, upon the loss of the killer phenotype M dsRNA was lost, while LA dsRNA was maintained. However, in some cases, both LA and M dsRNA were maintained, while only rarely they were both lost. M virus was less stable than LA. |
