Discovery of the yeast strain secreting the factor that inhibits the action of S.cerevisiae killer toxins K1, K2 and K28

Abstract

The detailed analysis of spontaneous fermentation processes in the local fruits and berries resulted in the detection of the Saccharomyces genus wild strain Kx. The latter can secret the factor X which inhibits the action of the toxins S.cerevisiae K1, K2 and K28 and has weak killer properties against sensitive and killer-type yeast. The effect of inhibition and strain killer ability fully concurs with each other and depends on pH medium in the interval of 4.0-5.2. These properties have not observed in lower pH media. Strain Kx ability is encoded by M fraction of ds RNA with size about 2.5 kb. Elimination of M ds RNA results in the loss of the effect of killer ability and inhibition, thereto, the factor X can be assumed being the protein, coded by M ds RNA. The toxin and the inhibitor can be considered being the same protein. The inhibition could be related to the competition between the recognition receptors on the cell wall or the membrane of the cell. In order to intensify the effect of inhibition, we have modified the method of the preparation of sensitive yeast lawns. During the period of five years, there were five Saccharomyces genus strains discovered, identic to the strain Kx. It proves that the strain with antikiller properties we have detected is not a random case. Such factors are likely may be detected in other yeast genera. The data we have presented about antikiller effect can bring new insights on killer or other biocidical systems existing in nature.