UC Santa Cruz

Bacteria-bacteria interactions are critically important to fundamental biological processes in the ocean such as nutrient cycling and the carbon pump. These interactions are often governed by physical and chemical effectors that are poorly understood. The presence and relative abundance of bacterial predators utilizing the type VI secretion system (T6SS) were examined at local and global scales to better understand local bacterial community dynamics, through the use of a two-year time series of weekly samples from Monterey Bay and metagenome data from the TARA Oceans project. We found that relative abundance of bacterial predators in both datasets is negatively correlated with availability of essential nutrients. Statistical analyses suggest that, when abundant, these bacterial predators reduce the abundance of other bacterial species thereby influencing bacterial community composition. Taken together, these data show that predatory bacteria play a role in determining bacterial community structure under given environmental conditions and may influence ecosystem functions performed by the bacterial community.