Photoprotective compounds (carotenoids and mycosporines) in freshwater Patagonian yeasts

LIBKIND FRATI, D; PÈREZ, P; SOMMARUGA, R; DIÉGUEZ, MC; FERRARO, M; BRIZZIO, S; ZAGARESE, H; VAN BROOCK, MR

Bariloche, Arg

Congreso; XXXIX Reunión Anual de SAIB; 2003

The synthesis of carotenoids and/or mycosporines (MYC) which have respectively antioxidant and UVR sunscreen properties is a common strategy in the photoprotection of microorganisms. The production of these compounds by freshwater yeast strains grown under PAR and UVR was assessed. In most red species, caretonoid synthesis was stimulated under PAR or UVR+PAR irradiation. This response was higher when constitutive levels of pigments (in the dark) were lower. This suggests that cells with higher constitutive levels of carotenoids are less responsive to induction by UVR-PAR. Four yeast strains were able to produce a UV-absorbing compound (309-310 nm) when exposed to PAR or UV-PAR identified as mycosporine-glutaminol-glucoside. This is the first time that the production of MYCs by yeasts is reported.  All strains that developed under UVR-PAR were able to synthesize carotenoids either constitutively or in response to PAR exposure, and a few of them also produced MYCs. Collectively, our results suggest that the presence of carotenoids, either alone or in combination with MYCs, are required for sustaining yeast growth under exposure to UVR-PAR.