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. Intellectual Merit: 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. Broader Impacts: The project will provide training for 15 undergraduate students (including students from the California Alliance for Minority Participation in Science, Engineering, and Mathematics), 2 graduate students and a postdoc. The project will also build on a science-education internship program that was developed with Crystal Cove State Park in California. The Park is host to more than 1.2 million visitors and 10,000 K-12 students each year. The outcome of this program will be topical science teaching kits that reside in the Marine Research Facility of the Park to be used by middle and high school teachers and students. These kits will connect marine microbiological research to the standards-based curricula of California and National Science Standards, educate the public on this NSF research and assist in the training of Science, Technology, Engineering, and Math (STEM) K-12 teachers. The results will be disseminated at national conferences, including American Educational Researchers Association (AERA) and National Association of Research on Science Teaching (NARST), while the curriculum and video productions will be hosted on the website of the UCI Center for Learning in the Arts Sciences and Sustainability.
