- Bacteriophages play an important role in plankton population dynamics and biogeochemical cycling, but their community dynamics and diversity are still poorly known, especially in fresh waters.
- We conducted a 1-year investigation of the T4-like bacteriophages in the surface waters of two Western European peri-alpine lakes (lakes Annecy and Bourget), using fingerprinting and cloning-sequencing approaches targeting the major capsid protein g23 gene.
- Our results suggest that T4-like bacteriophages are diverse (we found several new sequences) and differed substantially between the two lakes. Further, these phages displayed seasonal patterns with marked shifts in community composition.
- Examining the dynamics of some individual constituents (e.g. DGGE bands), we found that (i) the majority of these myoviruses were rare (mean relative abundance <1%) and only a few were abundant (mean relative abundance >5%); (ii) the dominance of the most abundant DGGE bands changed throughout the year and their dynamics were very different between the two lakes; (iii) only a few bands (e.g. <20%) were detectable throughout the year and their proportion was higher in the oligomesotrophic Lake Bourget.
- Our results suggest a highly dynamic T4-like myoviral assemblage. T4-like-viruses seem to conform to a standard model of community organisation and a common type of species abundance curve, with mainly rare organisms that occasionally may become abundant (termed a ‘seed bank’ for virus assemblages).