Phylogenetic distribution in yeasts of the capacities for photoreactivation and for temperature-sensitive dark recovery following inactivation by ultraviolet radiation.

Abstract

Eighty-three species of yeasts representing 12 perfect and 10 imperfect genera were tested for temperature-sensitive dark recovery and for direct photoreactivation after inactivation by ultraviolet radiation (uv). With the single exception of Torulopsis inconspicua, all species exhibit temperature-sensitive dark recovery. In contrast, the ability to photoreactivate appears to be a genus-delimited characteristic. All test organisms unequivocally assignable to the genera Cryptococcus, Debaryomyces, Endomycopsis, Hansenula, Nadsonia, Rhodotorula, Saccharomyces, Sporobolomyces, Sporotrichum, and Trigonopsis photoreactivate. Photoreactivation was not observed among representatives of the genera Brettanomyces, Hanseniaspora, Kloeckera, Lipomyces, Nematospora, Pichia, Saccharomycodes, Schizosaccharomyces, or Schwanniomyces. The systematically heterogeneous genera Candida, Torulopsis, and Trichosporon include both photoreactivating and non-photoreactivating species. The evolutionary, radiobiological, and taxonomic significances of genus-independent temperature-sensitive dark recovery and of genus-dependent photoreactivation are discussed.