Microbial methane emissions from the non-methanogenesis processes: A critical review

Area of Science:

• Microbiology
• Environmental Science
• Biogeochemistry

Background:

• Methane is a potent greenhouse gas, traditionally viewed as a methanogenesis end-product.
• Emerging evidence shows methane production by various microbes in oxygenated environments.
• This non-methanogenesis pathway represents a significant, understudied source of methane emissions.

Purpose of the Study:

• To systematically review microorganisms involved in non-methanogenesis methane production.
• To elucidate the potential mechanisms driving methane formation in these processes.
• To discuss the environmental significance and future research directions.

Main Methods:

• Systematic literature review of microbial methane production.
• Analysis of proposed biochemical pathways for methane formation.
• Synthesis of data on environmental distribution and flux.

Main Results:

• Cyanobacteria produce methane via methyl phosphonate demethylation or light-driven productivity.
• Algae utilize methylated sulfur compounds for methane synthesis.
• Fungi use methionine, and purple non-sulfur bacteria reduce CO2 via nitrogenase.

Conclusions:

• Microbial non-methanogenesis is a key contributor to global methane emissions.
• Further in-situ research and improved modeling are needed to quantify these fluxes.
• Investigating novel enzyme systems can enhance understanding of microbial methane production.