[Isolation and properties of merodiploid strains with F-factor including the pts-region of the Escherichia coli K-12 chromosome]

Abstract

A technique of hybridization of haploid methanol-utilizing yeast Pichia pinus MH4 is worked out using UV- and N-nitrosoguanidine-induced auxotrophic mutants. Vegetative diploid cultures are isolated. Tetrad analysis and random spore analysis have revealed a meiotic nature of spores, recombination of genetic material in the process of sporulation and the chromosomal nature of some mutations. A possibility to construct a genetic map of the yeast Pichia pinus MH4 is demonstrated on the basis of tetrad analysis. Three linkage groups are revealed. The life cycle in a homothalic haploid yeast, Pichia pinus, was demonstrated. They are capable to form zygotes and meiotic spores under conditions preventing vegetative growth.