Effect of solar radiation on two Antarctic marine bacterial strains

• Language: unknown
• Published: 2002
• Subjects: bacterium; photosynthetically active radiation; regression analysis; solar radiation; ultraviolet radiation; Antarctica; Bacteria (microorganisms); Rickettsia sp. PAR; Antarctic; King George Island; Potter Cove; South Shetland Islands; Antarc*
• Online Access: https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_07224060_v25_n6_p453_Hernandez; https://hdl.handle.net/20.500.12110/paper_07224060_v25_n6_p453_Hernandez

Two Antarctic marine bacterial strains were isolated, characterised and exposed to solar radiation during summer at Potter Cove (King George Island, South Shetland Islands, Antarctica). The effect of photosynthetically available radiation (PAR), ultraviolet-A (UV-A) and ultraviolet-B radiation (UV-B) on viability was studied using petri dishes covered with cut-off filters and providing the following treatments: dark, PAR, PAR + UV-A, PAR + UV-A + UV-B. UV-A and UV-B radiation have similar negative effects on the viability of the two studied strains under high UV irradiance but different sensitivities were observed under low UV irradiance. The regression analysis showed a logarithmic relationship between loss of viability and UV-B dose, with a threshold effect at 4.2 kJ m-2 (unweighted integrated dose) beyond which there was a > 90% mortality. Hydrogen peroxide in Antarctic seawater under ambient UV radiation reached concentrations up to 1.45 μM. However, assays with one of the bacterial strains showed that there was no detectable effect of hydrogen peroxide over the range 0.5-50 μM, indicating that production of this reactive oxygen species was not directly involved in the observed loss of viability.