Classic techniques for improvement of industrial yeast strains. Part II ? Transmission of killer activity into laboratory and industrial strains of Saccharomyces cerevisiae by electrotransformation
Killer-sensitive strains of Saccharamocyces cerevisiae and Saccharomyces uvarum var. carlsbergensis were transformed by electroinjection using dsRNA isolated from a superkiller strain. Various recipient strains were used: both thermo-resistant and thermo-sensitive as well as mutants of industrial strains. Conversion of respiratory competent (rho+) into respiratory deficient (rho-) strains (mutants) resulted in a significant increase in the yield of electrotransformants and/or of long-term killer stability. Electrotransformation of rho- mutants of distillery and brewery strains resulted in more than 100 clones, which exhibited weak or strong killer activity over some or all of the experimental period of 10 months.