FORMATION OF RESPIRATORY ACTIVITY-STIMULA TING FACTOR BY YEAST OZONIZATION

Low doses of ozone were shown to stimulate the respiratory activity of yeasts at the stationary growth phase. This is caused by the accumula tion in the medium of low molecular thermostable factor(s) capable of biological activity. No formation of substances with similar physico-c hemical properties and biological activity was observed under other co nditions of incubation, without O-3 treatment. This indicates an impor tant role of oxidative stress in the induction of the factor. A cooper ative decrease in the plasma membrane permeability for endogenous meta bolites of low molecular mass (nucleotides) as well as a rise in the c ell sedimentation rate were observed at the concentrations of the fact or stimulating bioenergetic processes. Therefore, the biological effec t of the factor is probably mediated by its membrane-modifying action. This effect is not species-specific because the stimulation of respir ation by the yeast factor was discovered in other cells (bacteria).