[The protective role of pigments against UV rays in fungi isolated from the mesosphere].

Five among six species of microorganisms isolated from the mesosphere contained pigments which made them more resistant to the action of UV as compared to pigmentless microorganisms in the atmosphere of Earth. UV irradiation in the atmosphere is supposed to select resistant pigmented forms, so that they predominate in the mesosphere. To confirm this assumption, mutants of Aspergillus niger, Penicillium notatum and Circinella muscae were sported by irradiating them four times and then subjecting to stepwise selection. These mutants either synthesized pigments at a very low rate or did not produce them at all. No significant differences were found by studying the biomass, mycelium and sporeforming organs of the parent cultures and their mutants. However, their resistance to UV was not the same. Addition of the pigment apsergillin, isolated from the conidia of Aspergillus niger, to a suspension of the pigmentless (mutant) conidia of Penicillium notatum, the spores of Circinella muscae, and the vegetative cells of Micrococcus albus, before their irradiation with UV, considerably increased their resistance to this factor.