Inactivation of Saccharomyces cells by 8-methoxypsoralen plus pulsed laser irradiation in the wavelength range 308 nm-380 nm.

Two different strains of Saccharomyces cerevisiae, one diploid wild type and one haploid mutant deficient in excision repair were irradiated with laser pulses in the range 308 nm to 380 nm after 8-MOP treatment. Both the shoulder (Dq) and the final slope (Do) of the inactivation curves were dependent on wavelength which showed a broad minimum around 355 nm. No differences in inactivation were recorded after pulsed irradiations between the repetition rates of 5 Hz and 35 Hz. Irradiations with pulses of the energy density from 0.1 mJ/cm2 up to 26 mJ/cm2 resulted in a final slope increasing with pulse energy density. This was in contrast to the effects of irradiation alone.