“Phage-host dynamics in the ocean: untangling a complex network of interactions”
Nathan Ahlgren, BBT Faculty Candidate
Associate Professor, Clark University
Monday, February 24th, 10:00 AM
Gateway 1002
(Pastries and coffee will be served)
Phages (viruses that infect bacteria) are the most abundant biological entity on our planet and are important agents of mortality and evolutionary change. Characterizing the interactions phages have with their hosts is critical to understanding their influence on community diversity, structure, and functioning of microbial systems. Using marine cyanobacteria and their phages (cyanophages), this work seeks to tease apart the complex network of phage-host interactions to identify emergent patterns of these co-evolving communities. Using DNA sequencing with time-series studies in the Pacific and Atlantic, we find a common pattern of seasonality in phage-host networks, reflecting how cyanophages are likely following the cyclical patterns of their hosts. Individual phage ‘species’ however can have more varied dynamics, including those with persistent or stochastic patterns. By investigating infection patterns of >100 host and phage isolates, we find a wide range of infection patterns. Furthermore, these infection patterns appear to relate to variation in genomic islands of host genomes, notably the presence of phage defense genes. Together we are combining classic culture-base infection assays, genomic analyses, and high-throughput sequencing of natural communities over time to unveil how diverse phage and host communities are structured and intertwined with each other.