Microbial Drivers of Aquatic Organic Matter Degradation and Carbon Cycling

Microbial communities are central to the degradation and transformation of organic matter in marine as well as in freshwater ecosystems. Through their metabolic activities, they regulate nutrient regeneration, carbon fluxes, and the fate of organic carbon from surface waters to the deep ocean. Advances in molecular, isotopic, and -omics approaches have revealed remarkable diversity and functional potential among marine microbes. However, important gaps remain in our ability to link specific taxa, consortia, and pathways to measured rates and modes of organic matter breakdown across different marine environments. In addition, the impacts of environmental variability, such as temperature shifts, nutrient limitation, oxygen gradients, and changing ocean water chemistry, on these microbial processes are still not fully resolved, limiting our capacity to predict ecosystem responses to ongoing global change.This Research Topic aims to advance our mechanistic understanding of how marine microbial communities mediate organic matter degradation and, in turn, influence marine and freshwater carbon cycling. We seek contributions that go beyond purely descriptive community surveys and instead connect microbial composition, function, and activity to specific decomposition processes and biogeochemical outcomes. Key questions include: Which microbial populations and consortia are the principal drivers of organic matter breakdown in different environmental settings? How do their metabolic pathways and interactions determine the fate of dissolved and particulate organic matter? How do physical and chemical drivers—such as temperature, nutrient availability, oxygen, and pH—modulate these processes on temporal and spatial scales? We particularly welcome studies that integrate field observations, experimental manipulations, and modeling, as well as methodological innovations that improve our ability to trace, quantify, or predict microbial contributions to organic matter degradation under present and future ocean scenarios.This Research Topic welcomes original research, reviews, mini reviews, perspectives, methods, and hypothesis/theory papers that address microbial mediation of organic matter degradation in marine and freshwater environments. Suitable contributions may include, but are not limited to:o Identification and characterization of key microbial taxa and consortia involved in organic matter decompositiono Mechanistic studies of metabolic pathways and microbe–microbe or microbe–particle interactionso Environmental controls (e.g., temperature, nutrients, oxygen, pH) on microbial decomposition processeso Comparative studies across water masses, depth gradients, coastal–offshore systems, or distinct biogeochemical regimeso Innovative approaches for monitoring, tracing, or modeling microbial activity and organic matter transformation in situ or in experimental systems.o Impacts of climate change and anthropogenic pressures (e.g., warming, deoxygenation, acidification, pollution, atmospheric deposition) on microbially driven organic matter degradation and carbon cycling Topic editors: Elisabeth Bondar-Kunze, Royston Uning Source: https://www.frontiersin.org/research-topics/77155/microbial-drivers-of-aquatic-organic-matter-degradation-and-carbon-cycling