The factors that control the occurrence of lysogeny in the marine environment are poorly understood. To study which factors might influence the lysogenic switch in natural populations, we have performed a seasonal study of lysogeny in Tampa Bay. Biweekly sampling included analysis for inducible prophage (detection of lysogens) in both heterotrophic bacteria and marine Synechococcus, primary production, bacterial production, nutrients, chlorophyll a, and bacterial and viral direct counts.
Temperature ranged from 15 to 20°C over the project period, and the major input of nutrients coincided with the rainfall that occurred between June and October.
The greatest occurrence of lysogeny coincided with the winter months, December through February (bottom panel in the figure above). This also coincided with the times of lowest water temperature, primary production, bacterial production, and bacterial direct counts.
A similar observation was obtained for lysogeny in Synechococcus.
This figure shows a spring bloom in Synechococcus counts and cyanophages, followed by a fall bloom in both. However, detectable Synechococcus lysogens were found only in the winter months (bottom panel). We interpret this to mean that lysogeny is favored during times of low resources, low host abundance and growth rate, as occurred in the winter months.
McDaniel, L., L.A. Houchin, S.J. Williamson, and J.H. Paul. 2002. Lysogeny in marine Synechococcus populations. Nature 415:496
Williamson, S., L. McDaniel, L. Houchin, and J.H. Paul. 2002. Seasonal variation in lysogeny as depicted by prophage induction in Tampa Bay, Florida. Applied and Environmental Microbiology. 68:4307-4314