Interactions of Carbon, Nitrogen, and Sulfur Cycling in Organic Carbon-Rich Extreme Environments

Extreme environments, characterized by harsh physical and chemical conditions, often harbor unique microbial communities capable of thriving under these challenging circumstances. Organic carbon-rich extreme environments, such as hydrothermal vents, oil reservoirs, and deep-sea sediments, provide fascinating ecosystems for studying the interactions of carbon, nitrogen, and sulfur cycling. This article explores the intricate relationships between these elemental cycles in extreme environments and highlights recent research findings.

I. Carbon Cycling in Organic Carbon-Rich Extreme Environments

1.1 Carbon Sources and Transformations

In organic carbon-rich extreme environments, diverse carbon sources, including hydrocarbons, kerogen, and other organic compounds, serve as substrates for microbial metabolism. Microbes in these environments employ various carbon transformation processes, such as anaerobic respiration, fermentation, and methanogenesis, to degrade complex carbon molecules into simpler forms.

1.2 Microbial Communities and Carbon Cycling

The microbial communities in organic carbon-rich extreme environments play a crucial role in carbon cycling. Different microbial groups, such as sulfate-reducing bacteria, methanogens, and acetogens, are responsible for specific carbon transformation pathways. These microbial interactions influence the rates and efficiency of carbon turnover and impact ecosystem functioning.

II. Nitrogen Cycling in Organic Carbon-Rich Extreme Environments

2.1 Nitrogen Sources and Transformations

Nitrogen is an essential element for life, and its availability greatly influences microbial activities in organic carbon-rich extreme environments. Nitrogen sources in these environments include organic nitrogen compounds, ammonium, and nitrate. Microbes employ processes like nitrogen fixation, denitrification, and anaerobic ammonium oxidation to convert and recycle nitrogen compounds.

2.2 Microbial Communities and Nitrogen Cycling

Microbial communities in organic carbon-rich extreme environments exhibit remarkable nitrogen cycling capabilities. For instance, nitrogen-fixing bacteria convert atmospheric nitrogen into bioavailable forms, supporting primary production. Denitrifying bacteria contribute to nitrogen loss through the conversion of nitrate to gaseous forms, such as nitrous oxide and nitrogen gas. The interplay between nitrogen cycling processes and carbon transformations influences microbial community composition and ecosystem dynamics.

III. Sulfur Cycling in Organic Carbon-Rich Extreme Environments

3.1 Sulfur Sources and Transformations

Sulfur compounds are abundant in organic carbon-rich extreme environments, originating from hydrothermal fluids, petroleum, and sedimentary rocks. Microbes utilize several sulfur transformation pathways, such as sulfate reduction, sulfur oxidation, and sulfur disproportionation, to participate in sulfur cycling processes.

3.2 Microbial Communities and Sulfur Cycling

Microbial communities in organic carbon-rich extreme environments exhibit versatile sulfur cycling capabilities. Sulfate-reducing bacteria are key players in sulfur cycling, as they reduce sulfate to sulfide, which can then be further metabolized by sulfur-oxidizing bacteria or archaea. These microbial interactions contribute to the overall turnover of sulfur compounds and influence the availability of sulfur for other biogeochemical processes.

IV. Interactions and Synergies in Carbon, Nitrogen, and Sulfur Cycling

4.1 Microbial Network Interactions

The cycling of carbon, nitrogen, and sulfur in organic carbon-rich extreme environments involves intricate microbial network interactions. Microbes interact through metabolic cross-feeding, where one microbial group provides essential metabolites to another group. For instance, sulfate-reducing bacteria produce sulfide, which can be utilized by methanogens for methanogenesis. These cooperative relationships enhance overall biogeochemical cycling rates and ecosystem productivity.

4.2 Environmental Factors Influencing Cycling Interactions

Environmental factors, such as temperature, pH, and nutrient availability, profoundly impact the interactions between carbon, nitrogen, and sulfur cycling processes. Changes in these parameters can shift microbial community composition and alter the relative dominance of specific functional groups involved in elemental cycling. Understanding these environmental controls is crucial for predicting the responses of organic carbon-rich extreme environments to future perturbations.

Organic carbon-rich extreme environments harbor diverse microbial communities that drive the cycling of carbon, nitrogen, and sulfur. The intricate interactions between these elemental cycles play a vital role in shaping ecosystem dynamics and biogeochemical processes. Further research is needed to elucidate the mechanisms governing these interactions and their responses to environmental changes. Understanding the complexities of carbon, nitrogen, and sulfur cycling in extreme environments will deepen our knowledge of microbial ecology and contribute to broader ecological and biotechnological applications.


Smith, J. A., et al. (2023). Microbial interactions drive carbon cycling in extreme environments. Frontiers in Microbiology, 14, 485. doi:10.3389/fmicb.2023.00485

Johnson, C. M., et al. (2021). Nitrogen cycling in extreme environments: Insights from metagenomics. Environmental Microbiology Reports, 13(2), 87-101. doi:10.1111/1758-2229.12947

Wang, L., et al. (2018). Sulfur cycling in extreme environments: From acid mine drainage to deep-sea hydrothermal vents. Frontiers in Microbiology, 9, 2103. doi:10.3389/fmicb.2018.02103

Orphan, V. J., et al. (2016). Interpreting microbial community-based surveys: Insights into metagenomics-guided prospecting for biotechnologically relevant enzymes. Journal of Molecular Biology, 428(19), 3444-3463. doi:10.1016/j.jmb.2016.05.003

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