VIROMES BEYOND PATHOGENS: ROLE OF VIRUSES IN ECOSYSTEM FUNCTIONING

Among all biological entities in the biosphere, viruses are the most abundant, outnumbering cellular organisms by an order of magnitude.They have been studied mainly as agents of disease with a focus on human, animal, and plant pathogenic viruses; research has predominantly emphasized pathogenic viruses in humans, animals, and plants.Recent advances in sequencing technologies and metagenOMIC approaches have found that the majority viral diversity occurs outside of pathogenic-related ecologies and play important roles as regulators of ecosystem processes.For example, viruses can be mediators of microbial diversity and evolution, drivers of global biogeochemical cycles, and vehicles of horizontal gene transfer and can shape community dynamics in marine, freshwater, soil, extreme, and host-associated environments.Viruses can function as ecosystem engineers by liberating organic matter through lysis of host cells (viral shunt), by reprogramming host metabolism using auxiliary metabolic genes (AMGs), and stabilizing ecosystems through kill the winner dynamics.They are also important in stimulating microbial adaptation and resilience to environmental stress.This review synthesizes the findings from several studies to distill our current understanding of the functional roles viruses play in ecosystems, beyond their pathogenic perception.We will also discuss methodological advances, gaps in knowledge, and future research directions that will be important to include viruses in models of ecosystem functioning, global nutrient flow, and sustainability.