No abstract

Rationale Mycosporine‐like amino acids (MAAs) are UV‐absorbing compounds produced by fungi, algae, lichens, and cyanobacteria when exposed to UV radiation. These compounds have photoprotective and antioxidant functions and have been widely studied for possible use in sunscreens and anti‐aging products. This study aims to identify MAA‐producing cyanobacteria with potential application in cosmetics. Methods A method for the identification of MAAs was developed using ultrahigh‐performance liquid chromatography with diode array detection coupled to quadrupole time‐of‐flight mass spectrometry (UHPLC‐DAD/QTOFMS). Chromatographic separation was carried out using a Synergi 4 μ Hydro‐RP 80A column (150 × 2,0 mm) at 30°C with 0.1% formic acid aqueous solution + 2 mM ammonium formate and acetonitrile/water (8:2) + 0.1% formic acid as a mobile phase. Results Out of the 69 cyanobacteria studied, 26 strains (37%) synthesized MAAs. Nine different MAAs were identified using UHPLC‐DAD/QTOFMS. Iminomycosporines were the major group detected (7 in 9 MAAs). In terms of abundance, the most representative genera for MAA production were heterocyte‐forming groups. Oscilatoria sp. CMMA 1600, of homocyte type, produced the greatest diversity of MAAs. Conclusions The UHPLC‐DAD/QTOFMS method is a powerful tool for identification and screening of MAAs in cyanobacterial strains as well as in other organisms such as dinoflagellates, macroalgae, and microalgae. The different cyanobacterial genera isolated from diverse Brazilian biomes and environments are prolific sources of MAAs.

No abstract

Anabaenopsis elenkiniiMiller forms bloom in the alkaline shallow lakes of the Brazilian Pantanal. The A. elenkinii CCIBT1059 strain was isolated from one of these alkaline lakes and the experiments were made in growth chamber during 30 days, under modified medium BG-11 (3 % NaNO 3 ), temperature 25 ºC, photoperiod 12-12 light-dark cycle and irradiance of 80-100 µmol photons m -2 s -1 at three different pH values: 7.0, 9.5 and 10.5. In relation to growth rate and cell yield the higher values were observed at pH 10.5. Morphologically, the longest trichomes were found at pH 7 (maximum 45 cells) in comparison with pH 9.5 (maximum 32 cells) and pH 10.5 (maximum 23 cells). The occurrence of heterocytes was observed in all treatments, but akinetes were never formed. The morphometric variability within each treatment between exponential and stationary growth was clearly higher than the variability among different treatments in most cases. Our results indicate that A. elenkinii is typical of alkaline systems and also that in lower pH values the growth limitation can occur in terms of number of cells and biomass. This study represents the first experimental evidence of the effects of pH on growth rate, cell yield and morphometric variability of A. elenkinii.