Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

Effects of increased UV radiation on activity and diversity of bacterioplankton in the NW Mediterranean Sea

We have measured the effect of UV radiation using a single-cell level approach on heterotrophic bacteria from a Mediterranean coastal station. We performed short-term experiments exposing samples to natural light conditions and studied the effects of PAR and UV radiation on bacterioplankton after exposure with the use of cutoff filters.

We used a combination of physiological probes and flow cytometry to assess the effects on the activity and integrity of the cells. Heterotrophic bacterial activity measured by CTC reduction decreased after sunlight exposure with a concomitant inhibition on total and cell-specific leucine incorporation. In contrast, no apparent effect was detected on cell viability as assessed by the simultaneous staining with propidium iodine and SybrGreen.

We applied the MAR-FISH technique in order to test the sensitivity of the different bacterial groups to the sunlight radiation. Bacteria labelled with the Gamma-Proteobacteria probes appeared to be resistant to the radiation, with no detectable change in their activity after the exposure.

On the contrary, the alpha-Proteobacteria bacteria exhibited a higher sensitivity to the radiation decreasing significantly their activity as measured by the cell-specific incorporation of labelled aminoacids and ATP. This trend was recurrent over two different seasonal periods. Our results suggest that UV radiation is an important modulator of short-term changes in single-cell activity of bacterioplankton, and naturally dominating phylogenetically distinct groups of bacteria have different sensitivity to radiation.

Informazioni correlate

Reported by

Institut de Ciències del Mar-CMIMA
Pg Marítim de la Barceloneta 39-47
08003 Barcelona
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