Theoretical and experimental evidence of extinction and coexistence of killer and sensitive strains of yeast grown as a mixed culture in water.

Theoretical and experimental evidences of extinction and coexistence during batch interaction of killer and sensitive strains of Saccharomyces cerevisiae grown as a mixed culture in pure water are provided. The experimental results show that in the limited nutrient conditions of growth in pure water, the killer yeast is subject to extinction when the initial concentration ratio of killer to sensitive yeast is 1:100. However, if the initial concentration ratio of killer to sensitive yeast is 1:1, both strains coexist.

Recovery of an oscillatory mode of batch yeast growth in water for a pure culture.

New experiments that we conducted show an oscillatory mode of batch yeast growth in water, for a pure culture of the T206 strain of Saccharomyces cerevisiae. The oscillations are damped over time, allowing the cell concentration to stabilize at the stationary equilibrium. A new proposed model that includes the complete cell growth dynamics is introduced and showed to recover the experimental oscillatory results.

Electron microscopy of the K2 killer effect of Saccharomyces cerevisiae T206 on a mesophilic wine yeast.

A mesophilic wine yeast, Saccharomyces cerevisiae CSIR Y217 K-R- was subjected to the K2 killer effect of Saccharomyces cerevisiae T206 K+R+ in a liquid grape medium. The lethal effect of the K2 mycoviral toxin was confirmed by methylene blue staining. Scanning electron microscopy of cells from challenge experiments revealed rippled cell surfaces, accompanied by cracks and pores, while those unaffected by the toxin, as in the control experiments, showed a smooth surface.

Genetic and fermentation properties of the K2 killer yeast, Saccharomyces cerevisiae T206.

Saccharomyces cerevisiae T206 K+R+, a K2 killer yeast, was differentiated from other NCYC killer strains of S. cerevisiae on the basis of CHEF-karyotyping and mycoviral RNA separations. Genomic DNA of strain T206 was resolved into 13 chromosome bands, ranging from approximately 0.

Genomic comparisons among parental and fusant strains of Candida shehatae and Pichia stipitis.

DNA-DNA binding experiments on selected fusants of Candida shehatae and Pichia stipitis showed that the nucleus of these strains was composed predominantly of Pichia DNA. Electrophoretic karyotyping revealed that the fusants contained four chromosomes, similar to those found in the Pichia parental strain. In addition, the fusants showed only marginal increases in cell DNA content when compared with the parents.