Phages infect bacteria and can influence bacterial infection dynamics
Tripartite species interaction: infection dynamics of pipefish infecting vibrios and their temperate phages
Research project at the GEOMAR | Helmholtz Centre for Ocean Research Kiel, Pipefish group (Dr. Olivia Roth)
Bacteriophages (viruses that infect bacteria) play a significant role in host-parasite interactions: with up to 108 particles per mL in marine waters, viruses are the most abundant biological entity on earth and have supposedly profound effects on ecosystem composition and dynamics (Fuhrmann, 1999; Wilhelm and Suttle, 1999; Brockhurst et al., 2006; Vos at al., 2009; Stern and Sorek, 2011; ).
One type of bacteriophages are so-called temperate phages that have two different reproductive strategies. They either lyse the infected cell and disperse horizontally through burst of their host cell or they integrate into the bacterial chromosome and are vertically transmitted to the bacterial daughter cells (lysogenic cycle). Whether a temperate phage enters the lytic or the lysogenic cycle depends on environmental factors, e.g. temperature, nutrients, salinity, (UV) radiation and/or oxygen conditions (Kokjohn and Sayler, 1991; Jiang and Paul, 1994, 1996; Weinbauer et al., 2003).
We hypothesized a link between bacterial resistance to phages and bacterial harm to eukaryotic hosts (in this case pipefish Syngnathus typhle). We sampled Vibrio bacteria from pipefish, isolated vibriophages from the bacteria and constructed a replicated, fully reciprocal 75 × 75 phage-bacteria infection matrix. The phage-bacteria infection network showed a nested structure with some highly susceptible bacteria and some resistant bacteria, whereas most bacteria were susceptible to a small subset of phages (intermediate susceptible).
Our results further showed that phage-susceptible Vibrios were more harmful to the pipefish. We conclude that research across more than two species levels is needed for a thorough understanding of infection patterns and host-parasite evolution.
The corresponding publication can be found here