Award: OCE-1829905

Drifting photosynthetic microbes in surface ocean waters carry out nearly half of global net primary production, both supporting the marine food web and modulating atmospheric carbon dioxide levels. The fate of carbon and nutrients in ocean ecosystems is controlled by myriad individual interactions within a highly interconnected planktonic food web. These planktonic organisms, largely microbial in nature, interact via the release and sensing of chemical cues. Viruses are both highly abundant and active in marine ecosystems, but their role in oceanic carbon and nutrient cycling has been difficult to quantify. During infection, viruses alter host cellular metabolism, stimulating the release of chemical compounds from intact cells that likely serve as cues to other organisms, potentially altering marine microbial community composition and spatial structure, increasing organism encounter rates, and subsequently, carbon and nutrient flux among trophic levels. This project aimed to identify the chemicals released by virus-infected cyanobacteria, quantify the response of heterotrophic bacteria to such chemical cues, and determine if virus infection enhanced interactions between marine cyanobacteria and other microbial community members. In doing so, the project addressed critical gaps in our understanding of how living organisms in the ocean interact with one another and contribute to ocean ecosystem health and productivity. Through a collaborative effort among viral ecologists, environmental chemists, and engineers this project determined the impact of viral infection on dissolved chemical compounds released from the marine cyanobacteriumSynechococcusand the subsequent chemotactic (motility in response to chemical cues) responses of heterotrophic bacteria using time-resolved metabolomics and microfluidics. Metabolites released from intact, virus infectedSynechococcusduring early stages of infection strongly attracted heterotrophic bacteria. Our findings establish that prior to cell lysis, virus infected picocyanobacteria release compounds that attract heterotrophic bacteria and infected cells may serve as long lasting (time scales of hours) and detectable nutrient point sources in surface ocean waters. The work has implications for our understanding of how marine viruses influence ecosystem scale carbon and nutrient flux. In addition, through the award, a widely accessible and high-throughput microfluidic chemotaxis screening device was developed that will accelerate knowledge generation in the field of marine chemical ecology and beyond. The project supported the scientific training of four graduate students and ten undergraduate students through direct mentored research. In addition, through the award, a one-day workshop titled Advancing microfluidics and metabolomics in microbial ecology was organized in conjunction with the ASLO Ocean Sciences Meeting and was held on February 24, 2022. The workshop included three keynote presentations and fostered discussion among leaders and early career researchers in the fields of microfluidics, metabolomics, and microbial ecology. Last, the award supported development of two course based undergraduate research experiences (CUREs): one phage biology module for introductory level biology undergraduate students and one microbiome sequencing module for upper-level microbiology undergraduate students. Last Modified: 12/29/2023 Submitted by: SheriAFloge