Corina Brussaard, Dominique Marie, Runar Thyrhaug, Daniel Vaulot, and Gunar Bratbak.
Dept. Microbiology, Univ. Bergen, N-5020 Bergen, Norway
The significance of viruses infecting phytoplankton cells has received much attention the last years. Algal viruses have been detected in different algal species and enumeration in natural waters suggests that they play an important role in phytoplankton dynamics. Causing lysis of the algal cells, viruses will also indirectly affect the carbon and nutrient flow in the pelagic systems.
However, until now not much is known on the cellular characteristics of viral infected phytoplankton cells. We have used flow cytometry to analyse changes in cellular parameters during viral infection as compared to non-infected cells of two axenic phytoplankton species (Phaeocystis pouchetii and Micromonas pusilla). Differences in forward angle, side angle scatter and autofluorescence were observed for both algal species. The use of fluorescent dyes furthermore yielded information on DNA content and viability which is not easily obtained with other methods. The use of these techniques in this field of research is new and provides detailed information for the study of the ecophysiology of viral infected phytoplankton species.