Molecular Microbiology Research 2024, Vol.14, No.4, 198-207 http://microbescipublisher.com/index.php/mmr 198 Feature Review Open Access Roles of Marine Microorganisms in the Carbon, Nitrogen, and Sulfur Cycles Bing Wang, Hongwei Liu Aquatic Biology Research Center of Cuixi Academy of Biotechology, Zhuji, 311800, Zhejiang, China Corresponding author: hongwei.liu@cuixi.org Molecular Microbiology Research, 2024, Vol.14, No.4 doi: 10.5376/mmr.2024.14.0022 Received: 06 Jul., 2024 Accepted: 16 Aug., 2024 Published: 30 Aug., 2024 Copyright © 2024 Wang and Liu, This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Wang B., and Liu H.W., 2024, Roles of marine microorganisms in the carbon, nitrogen, and sulfur cycles, Molecular Microbiology Research, 14(4): 198-207 (doi: 10.5376/mmr.2024.14.0022) Abstract Marine ecosystems play a crucial role in global biogeochemical cycles, particularly through their microbial components. These microorganisms significantly impact the carbon, nitrogen, and sulfur cycles through their complex physiological and metabolic mechanisms, thus profoundly influencing global climate. This study focuses on analyzing the roles of marine microorganisms in carbon sequestration, microbial degradation of organic carbon, and the production and oxidation of methane in the carbon cycle; nitrogen fixation, nitrification, and denitrification in the nitrogen cycle; and sulfate reduction and sulfur oxidation in the sulfur cycle. By delving into the interactions and environmental feedbacks of these biogeochemical processes, this research provides a comprehensive perspective on the role of marine microorganisms in these key elemental cycles, offering scientific bases and strategic recommendations for future research on marine microorganisms and the management of global climate change. Keywords Marine ecosystems; Biogeochemical cycles; Microorganisms; Carbon cycle; Nitrogen cycle 1 Introduction Marine ecosystems are dynamic environments where the cycling of essential elements such as carbon, nitrogen, and sulfur is driven by complex biogeochemical processes. These cycles are fundamental to the functioning of marine ecosystems and are tightly interwoven with energy fluxes across the biosphere. The transformation and mobilization of these bioessential elements are primarily mediated by microorganisms through their diverse metabolic activities (Dang and Chen, 2017; Wasmund et al., 2017; Hu et al., 2018). The marine nitrogen cycle, for instance, involves multiple biogeochemical transformations such as nitrogen fixation, nitrification, and denitrification, which are crucial for maintaining the productivity and ecological balance of marine environments5. Similarly, sulfur cycling in marine sediments, driven by sulfate-reducing and sulfur-oxidizing bacteria, plays a significant role in linking sulfur transformations to the cycling of carbon and nitrogen (Pajares and Ramos, 2019). Marine microorganisms, including bacteria, archaea, and protists, are pivotal in driving the biogeochemical cycles of carbon, nitrogen, and sulfur. These microorganisms exhibit a wide range of metabolic capabilities that enable them to thrive in diverse marine habitats, from surface waters to deep-sea sediments (Liao et al., 2021). For example, chemolithoautotrophic microorganisms contribute to the marine carbon and nitrogen cycles by harvesting energy from inorganic chemical bonds and fixing inorganic carbon (Dang and Chen, 2017). Sulfur-oxidizing bacteria protect marine ecosystems from sulfide toxicity and link sulfur transformations to carbon and nitrogen cycling. The metabolic activities of these microorganisms not only sustain marine ecosystems but also have profound implications for global biogeochemical cycles and climate change (Hutchins and Fu, 2017; Plominsky et al., 2018). In this study，we seek to highlight the diverse metabolic pathways and eco-energy strategies of marine microbes and their contributions to biogeochemical processes，to address the impact of human activities and environmental changes on these microbial processes, and identify knowledge gaps that require further investigation to comprehensively understand how marine microorganisms affect global element cycling and the functioning of marine ecosystems.
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