Certain yeast strains have been reported to produce a novel toxin with a power to kill pathogenic organisms.Presence of double stranded linear plasmids have been shown to be the genetic basis for killer toxin production.In the present study search for such a novel killer toxin have been done in linear double strandedplasmid containing yeasts Kluveromyces lactis, Pichia acaciae and Pichia pastoris. Research have been conducted on their ability to produce toxin and the effects of this toxin on pathogenic organism like Candida albicans.