Project: Cyanophage-Synechococcus interactions in complex communities

Description from NSF award abstract:
Viral-induced mortality of marine microorganisms alters the quantity and quality of pools of dissolved organic matter in the oceans, shuttling organic matter back into the microbial loop and away from the larger marine food web. A major hindrance to understanding the role of viruses in biogeochemical cycling is that we know surprisingly little about which viruses infect which bacteria in the marine environment. In this project, a network-based framework will be used to investigate marine phage-bacteria interactions in complex, multispecies communities. The research focuses on cyanophages, viruses that infect Synechococcus, an ecologically important cyanobacterium in the oceans. There are three parts of the project. The first part will identify genetic signatures of cyanophage-Synechococcus interactions by using laboratory evolution experiments and genomic sequencing. The second part will examine the temporal and spatial diversity of these candidate interaction genes in natural cyanophage populations, by comparing the full genome sequences of hundreds of isolates previously collected over many years. The third part will adapt the new method of viral-tagging to natural host populations to characterize cyanophage-Synechococcus interaction networks in the environment.

The role of viruses in global marine biogeochemical cycles depends on viral-induced mortality rates, which have been estimated to vary widely. The pattern and dynamics of who infects whom are central to our understanding of these rates as well as the role viruses play in marine nutrient cycling. This project will also contribute generally to our knowledge about viral diversity. The vast majority of marine viral sequences are not similar to any known diversity, and it is reasonable to conclude that many of these genes have to do with host recognition and infection. Finally, this project will develop a method of characterizing phage-bacteria interactions in natural, diverse microbial communities, thereby opening avenues for similar studies of viruses in other environments.

Note: This is an NSF Collaborative Research Project supported by OCE-1332740 (Lead PI Jennifer Martiny) and OCE-1332782 (Lead PI Marica Marston).