Microbial Engines: How Bacteria and Archaea Drive Global Carbon, Nitrogen, and Sulfur Cycles

This extensive technical review provides a detailed examination of how bacteria and archaea function as the primary engines of Earth's biogeochemical cycles. Microorganisms mediate the transformation and movement of essential elements, particularly carbon, nitrogen, and sulfur, between the biosphere and abiotic compartments. The article outlines key metabolic pathways, including diverse carbon fixation mechanisms, methanogenesis, nitrification, denitrification, and complex sulfur redox reactions. A major highlight is the exploration of novel metabolisms like MISO, where microbes couple sulfide oxidation directly to iron oxide reduction, fundamentally altering our understanding of anaerobic respiration and elemental coupling. To study these complex processes, researchers employ a sophisticated toolkit of culture-independent methodologies. Techniques such as metagenomics and metatranscriptomics reveal the genetic potential and active expression of microbial communities, while stable isotope probing and nanoscale secondary ion mass spectrometry directly link specific taxa to their metabolic functions. The text also details the application of CRISPR gene editing and isotopic fingerprinting to trace methane origins and metabolic fluxes. The review critically examines the impact of anthropogenic stressors on these microbial engines. Climate change, microplastic pollution, and nutrient imbalances are shown to disrupt microbial community structure and function, leading to reduced diazotroph diversity, altered greenhouse gas emissions, and severe coastal eutrophication. In response to these challenges, the article explores the potential of microbial community engineering and synthetic microbiomes for advanced bioremediation, utilizing synergistic microbial interactions to detoxify environments. Finally, the document addresses the significant challenge of integrating immense microbial complexity into predictive biogeochemical models. Overcoming issues of scale, functional redundancy, and unculturable rare biosphere taxa requires standardized multi-omics data and mechanistic modeling. Ultimately, understanding and harnessing these microbial processes is essential for environmental management, climate change mitigation, and the development of sustainable biotechnologies. Source: https://www.microecosci.com/posts/microbial-engines-how-bacteria-and-archaea-drive-global-carbon-nitrogen-and-sulfur-cycles