Killer yeast
A killer yeast is a yeast, such as Saccharomyces cerevisiae, which is able to secrete one of a number of toxic proteins which are lethal to receptive cells. The phenomenon was first observed by Louis Pasteur, as noted in 1877. These yeast cells are immune to the toxic effects of the protein due to an intrinsic immunity. Killer yeast strains can be a problem in commercial processing because they can kill desirable strains. The killer yeast system was first described in 1963. Study of killer toxins helped to better understand the secretion pathway of yeast, which is similar to those of higher eukaryotes. It also can be used in treatment of some diseases, mainly those caused by fungi.