The groove assay for quantitative estimating the killer toxin activity or susceptibility of S-cerevisiae strains to killer toxins

The sensitivity of commonly used well assay for estimating the killer toxin activity or susceptibility of sensitive yeast strains to the killer toxin treatment was markedly increased by growth retardation of sensitive cells i n the initial phase of the assay by using a high osmolarity medium and/or l ow temperature. Further improvement can be reached by channeling the diffus ion of the toxin molecules from the well to the groove filled with agar med ium that contains sensitive cells.