Polycyclic aromatic hydrocarbon (PAH) degradation coupled to methanogenesis

Area of Science:

• Environmental microbiology
• Bioremediation of polycyclic aromatic hydrocarbons (PAHs)

Background:

• Sediments from Baltimore Harbor were used to study anaerobic degradation of PAHs.
• Polycyclic aromatic hydrocarbons (PAHs) are persistent environmental pollutants.
• Previous studies have not fully elucidated the microbial pathways for PAH degradation under anaerobic conditions.

Purpose of the Study:

• To investigate the role of methanogenesis in the anaerobic degradation of PAHs.
• To identify microbial communities involved in PAH degradation in marine sediments.

Main Methods:

• Anaerobic enrichment cultures were established using Baltimore Harbor sediments and PAHs (naphthalene, phenanthrene).
• Bromoethanesulfonic acid, a methanogenesis inhibitor, was used to assess its impact on PAH degradation.
• 16S rRNA gene sequencing was performed for molecular characterization of the microbial communities.

Main Results:

• Sustained and transferable degradation of naphthalene and phenanthrene was observed in the enrichment cultures.
• Inhibition of methanogenesis by bromoethanesulfonic acid significantly reduced PAH degradation.
• Molecular analysis confirmed the elimination of methanogenic Archaea when methanogenesis was inhibited.

Conclusions:

• Methanogenesis is a key process in the anaerobic degradation pathway of PAHs like naphthalene and phenanthrene.
• Methanogenic Archaea play a significant role in the bioremediation of PAH-contaminated sediments.
• This study provides evidence for a specific microbial consortium involved in anaerobic PAH degradation.