Methane dependent denitrification- from ecosystem to laboratory-scale enrichment for engineering applications

Area of Science:

• Environmental microbiology
• Biogeochemical cycles
• Wastewater treatment technologies

Background:

• Managing nitrogen and carbon cycles is crucial for ecosystems.
• Connecting these cycles offers ecological and engineering benefits.
• Methane oxidation coupled to denitrification is a key process.

Purpose of the Study:

• To investigate methane-dependent denitrification coupled to anaerobic methane oxidation (n-DAMO).
• To explore the potential of n-DAMO for wastewater treatment.
• To identify the microorganisms and genes involved in this process.

Main Methods:

• Laboratory-scale reactor setup using river sediments.
• Cultivation and enrichment of n-DAMO prokaryotes.
• 16S rRNA gene analysis and functional gene (nod) targeting.
• Measurement of methane oxidation and nitrite removal rates.

Main Results:

• Established a functional n-DAMO reactor with significant nitrite removal rates (2.88 mmol L⁻¹ d⁻¹).
• Observed enrichment of NC10 phylum bacteria and increased methane oxidation rates.
• Identified novel n-DAMO organisms distinct from previously studied species.
• Successfully targeted the nitric oxide dismutase (nod) gene in enrichment cultures.

Conclusions:

• The study successfully demonstrated and characterized a novel n-DAMO process.
• n-DAMO organisms show significant potential for treating wastewater with dissolved methane.
• Further research into the nod gene and n-DAMO organisms can optimize wastewater treatment strategies.