Microbial communities in pyrene amended soil-compost mixture and fertilized soil

Area of Science:

• Environmental microbiology
• Bioremediation science

Background:

• Polycyclic aromatic hydrocarbons (PAHs) are persistent environmental pollutants with toxic metabolites.
• Organic amendment of contaminated soil using compost or farmyard manure aids PAH bioremediation by native microorganisms.
• Understanding the specific microbial degraders in these amended soils remains limited.

Purpose of the Study:

• To provide molecular insights into bacterial communities involved in pyrene degradation in organic-amended soils.
• To identify bacterial genera capable of degrading pyrene, a model PAH.
• To compare microbial communities in soil amended with compost versus farmyard manure.

Main Methods:

• Statistical analysis of bacterial genera abundance using DNA and RNA extracted from soil samples.
• Analysis of pyrene degradation mass balances using 13C-labeled pyrene.
• Enrichment culture experiments and near-complete genome reconstruction.

Main Results:

• Pyrene-degrading communities are complex, characterized by low abundance of individual degraders rather than dominant key players.
• Bacterial degrader communities differed significantly between compost-amended and farmyard manure-amended soils, despite similar degradation rates.
• Enriched pyrene-mineralizing bacteria did not dominate degradation in the actual soil environments.

Conclusions:

• PAH bioremediation in organic-amended soils involves diverse microbial communities with low abundance of specific degraders.
• Focusing on abundant key degrading species may be insufficient for evaluating PAH-degrading microorganisms in complex, high-organic matter soils.
• Future assessments should consider the high diversity and low abundance of specific PAH degraders.