Award: OCE-1737237

Viruses of microbes are pervasive across all ecosystems, including the worlds oceans, where the interactions they have with their hosts are of global significance (e.g., modulation of community structure and function and the release of organic matter and nutrients back into the environment). Historically, efforts to characterize the system-level influence of viruses focused principally on lytic infections, despite the predicted prevalence of lysogenic infections. This project brought together marine microbiologists and chemists to better characterize the complexities of these understudied lysogenic infections. An environmentally relevant model system was further developed and used to dissect these multifactorial relationships. Intellectual Merit: Our work revealed that genetically similar phages can have divergent influence on the competitiveness of their shared host in distinct environmental niches (planktonic vs biofilm lifestyles), possibly due to a complex form of phage-mediated allelopathy in which host-phage pairs form coalitions to challenge one another. Moreover, we identified a novel interaction between bacterial extrachromosomal elements (plasmids) and prophages. By demonstrating that loss of one or more distinct plasmids destabilizes the lysogenic-lytic switch, we uncovered a unique form of crosstalk between different mobile genetic elements. Additionally, we provide detailed and quantitative evidence for the malleable nature of bacterial metabolomes and lipidomes which has important implications for interpretation of omics data from field samples. Broader Impacts: Our work has implications for enhanced understanding of the eco-evolutionary dynamics of host-phage interactions that are pervasive in all ecosystems, including those with agricultural, industrial and medical relevance. Additionally, high-temporal resolution, coupled metabolome and lipidome results provide methodological considerations for future studies that seek to relate cellular composition with function in complex natural communities. The project directly supported the interdisciplinary training of 8 graduate students and many undergraduate students, including Research Experiences for Undergraduates (REU) students from the University of Tennessee Knoxville. The scientific advances made have been, or continue to be, presented to scientific communities through conferences, workshops, scientific meetings and peer-reviewed publications. Last Modified: 01/12/2024 Submitted by: AlisonBuchan