ABSTRACT

The most common fate of microbes in aquatic environments is to become a meal for a protest grazer. A major flux of carbon in aquatic environments is thus mediated through microbe-protist interactions. The mechanisms by which microbes attempt to avoid grazers likely include morphological, behavioral, and chemical resistance strategies, yet our knowledge of these is primitive and most progress is currently being made on harmful algal bloom species. One of the insights from the availability of multiple cyanobacterial genomes is that different cyanobacteria have very different cell surface structures as well as potentially different modifications of common structures. In addition, potential chemical resistance strategies have been detected in several available genomes. This project will address protest-cyanobacterial interactions with the collaboration of researchers with expertise in protist biology, cyanobacterial ecology, molecular genetics and genomics to examine the range of interactions between protists and cyanobacteria of the genus Synechococcus.

The investigators propose to use the recent availability of complete genomes and molecular genetics tools to determine the key cell structures under selection by diverse protist grazers. They will use "shot-gun" approaches (transposon mutagenesis and selection) to identify these structures and use available mutants to investigate specific known cell surface structures. They will also examine the role of some potential chemical defense enzymes, found through whole genome comparisons, in deterring grazing. The proposed research will provide qualitative and quantitative information on the role of various grazer deterrence strategies and new paradigms for understanding grazer-prey interactions.

Broader Impacts of the Proposed Research

The broader impacts of this work will include the training of undergraduate and graduate students, including those from under-represented groups. Scientific findings will be disseminated broadly though participation in national meetings and publication in peer-review journals. The findings may indicate a mechanistic basis for understanding microbe-grazer interactions, one of the major processes determining carbon cycling in the oceans. The investigators expect to define one or more model but ecologically relevant grazer-cyanobacteria pairs that could be used by the community for future studies. In addition, novel marine natural products that affect eukaryotic cells, with possible biotechnological applications, may be found through these activities.

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