Abundance and distribution of actively respiring bacteria in a coastal-offshore transect of the Tyrrhenian Sea (April 2007)

The abundance and distribution of actively respiring bacteria within the total prokaryotic community were estimated along the water column in a coastal-offshore transect crossing the Tyrrhenian Sea during spring 2007. Specific fluorochromes (SyBr Green and 3,5-cyano-dytolyl-tetrazolium chloride, CTC) were used to detect by flow cytometry the total prokaryotic community and the fraction of actively respiring bacteria, respectively. Bacterial numbers were compared to those determined by epifluorescence microscopy. Respiratory activity rates, leucine aminopeptidase and beta-glucosidase activity rates were also analysed, in order to relate the abundance of living cells to their functional role in the ecosystem functioning.