Gérald Grégori

Marine viruses make up an essential compartment of the marine ecosystem. They are the most abundant organisms and represent one of the biggest sources of unknown biodiversity. Viruses also have an important impact on bacterial and algal mortality in the ocean, and as such have a major influence on microbial diversity and biogeochemical cycling. However, little is known about the abundance and distribution patterns of viruses across the oceans and seas. Over the last 20 years, flow cytometry has been the technique of choice to detect and count the viral particles in natural samples. Nevertheless, due to their small size, the detection of marine viruses is still extremely challenging. In this article we describe how a new generation of flow cytometer which uses the side scatter (SSC) of violet photons from a 405 nm laser beam helps to improve the resolution for detecting marine viruses. To the best of our knowledge, this is the first report where virioplankton has been detected in aquatic samples using flow cytometry with a 405 nm violet SSC instead of a 488 nm blue SSC.