Presence and Abundance of the Type VI Secretion System in a Coastal Ocean Environment

Bacteria-bacteria interactions in the ocean are critically important to fundamental biological processes such as nutrient cycling. These interactions are governed by systems of communication and physical and chemical effectors that are often poorly understood. Here, we examine the presence and abundance of bacterial predators with access to the type VI secretion system (T6SS) in both a local dataset from Monterey Bay and worldwide datasets produced by the TARA oceans project. This community was tracked using a two-year time series of weekly water samples. We found that these predators vary through time in relative abundance with physical and biological habitat conditions. Our statistical analyses suggest that these bacteria may play a role in structuring the bacterial community when they are abundant by reducing the abundance of other bacterial species. Data from the TARA Oceans project confirms that the genes for T6SS predation are present in samples from around the world and are not anomalous to the samples obtained by our lab. Taken together, these data show that predatory bacteria may play a role in determining bacterial community structure under given environmental conditions and may influence ecosystem functions performed by the bacterial community.