Microbial-mediated soil dissolved organic nitrogen transformation pathways: Implications for groundwater nitrogen
Leyun Wang1, Miao Li1, Xiang Liu1
1School of Environment, Tsinghua University, Beijing 100084, China.
Journal of Environmental Sciences (China)
|July 2, 2025
Summary
Soil dissolved organic nitrogen (DON) transformation is key to groundwater quality. Microbes drive DON changes, converting complex molecules into simpler forms that can leach, highlighting the need for careful land and water management.
Area of Science:
- Environmental Science
- Soil Science
- Microbiology
Background:
- Soil dissolved organic nitrogen (DON) impacts groundwater quality, but its molecular transformation pathways are poorly understood.
- Understanding microbial roles in DON transformation is crucial for predicting nitrogen cycling and groundwater contamination.
Purpose of the Study:
- To investigate microbial-mediated DON transformation pathways in diverse land use soils.
- To identify key microbial players and their functions in DON decomposition and mineralization.
Main Methods:
- Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) for DON component analysis.
- 16S rRNA sequencing for microbial community profiling.
- Integration with FAPROTAX database and network analysis for functional insights.
Main Results:
- DON is the dominant nitrogen fraction, with composition varying by land use.
- Lignin-like and condensed aromatic compounds were major DON constituents.
- Key microbial genera (Solirubrobacter, 67-14, Bacillus) and functions (aromatic compound breakdown, cellulose hydrolysis) were identified.
- Network analysis revealed microbial cooperation in DON transformation, linked to N respiration.
Conclusions:
- Microbial communities significantly influence DON molecular composition and transformation.
- The conversion of high- to low-molecular-weight DON by microbes facilitates leaching.
- Managing microbial processes is essential to mitigate groundwater contamination from DON.
Related Concept Videos
01:30Environmental Applications of Microorganisms
283
Microorganisms play a pivotal role in maintaining ecosystem balance by recycling essential elements such as carbon, nitrogen, and phosphorus, as well as supporting processes like bioremediation, wastewater treatment, and biofuel production.Microbes in Elemental CyclesIn the carbon cycle, microorganisms decompose organic matter, releasing carbon dioxide via aerobic respiration. This carbon dioxide is subsequently used by photosynthetic organisms to synthesize organic compounds, closing the...
283
01:20Overview of Nitrogen Metabolism
8.6K
Nitrogen is a very important element for life because it is a major constituent of proteins and nucleic acids. It is a macronutrient, and in nature, it is recycled from organic compounds and stored in the form of ammonia, ammonium ions, nitrate, nitrite, or nitrogen gas by many metabolic processes. Many of these metabolic processes are carried out only by prokaryotes.
The largest pool of nitrogen available in the terrestrial ecosystem is gaseous nitrogen (N2) from the air, but this...
The largest pool of nitrogen available in the terrestrial ecosystem is gaseous nitrogen (N2) from the air, but this...
8.6K
01:22Inorganic Nitrogen Assimilation
116
Nitrogen is an essential element in biological systems, forming a crucial component of proteins, nucleic acids, and other cellular constituents. Many bacteria and archaea acquire nitrogen in the form of nitrate (NO₃⁻) or ammonia (NH₃), which are then assimilated into biomolecules through specific enzymatic pathways.Assimilatory Nitrate ReductionWhen nitrate enters the cell, it undergoes a two-step reduction process known as assimilatory nitrate reduction. Initially, the enzyme...
116
01:49The Nitrogen Cycle
54.4K
Nitrogen atoms, present in all proteins and DNA, are recycled between abiotic and biotic components of the ecosystem. However, the primary form of nitrogen on Earth is nitrogen gas, which cannot be used by most animals and plants. Thus, nitrogen gas must first be converted into a usable form by nitrogen-fixing bacteria before it can be cycled through other living organisms. The use of nitrogen-containing fertilizers and animal waste products in human agriculture has greatly influenced the...
54.4K
01:15Metabolism of Chemolithotrophs
185
Chemolithotrophs are microorganisms that obtain energy by oxidizing inorganic molecules such as hydrogen gas (H₂), ammonia (NH₃), reduced sulfur compounds (H₂S, S²⁻), and ferrous iron (Fe²⁺). Unlike heterotrophic organisms that rely on organic carbon, chemolithotrophs transfer electrons from these inorganic donors to the electron transport chain (ETC), generating a proton motive force (PMF) that drives ATP synthesis through oxidative phosphorylation.
185
00:46Bioremediation
20.2K
Bioremediation is the use of prokaryotes, fungi, or plants to remove pollutants from the environment. This process has been used to remove harmful toxins in groundwater as a byproduct of agricultural run-off and also to clean up oil spills.
20.2K