Autochthonous bioaugmentation accelerates phenanthrene degradation in acclimated soil

Area of Science:

• Environmental Microbiology
• Bioremediation Science

Background:

• Polycyclic aromatic hydrocarbons (PAHs) are persistent environmental pollutants.
• Bioaugmentation using specialized microbial communities can enhance PAH remediation.
• Phenanthrene (PHE) is a model PAH for studying microbial degradation pathways.

Purpose of the Study:

• To investigate the efficacy of PHE-acclimated soil for bioaugmentation.
• To characterize PHE degradation kinetics under different conditions.
• To assess the impact of co-contaminants on PHE biodegradation.

Main Methods:

• Microbial acclimation of soil with PHE.
• Inoculation of aqueous and soil cultures with acclimated soil.
• Kinetic modeling of PHE degradation (Gompertz and first-order equations).
• Evaluation of co-contaminant effects on PHE degradation.

Main Results:

• Acclimation enriched soil with specific PAH-degrading bacteria (Actinobacteriota, Streptomyces, Rhodococcus, Nocardioides, Sphingomonas, Mycobacterium).
• High PHE degradation efficiency (ca. 50 mg L⁻¹) was achieved in inoculated cultures.
• PHE degradation followed Gompertz kinetics in aqueous and first-order kinetics in soil.
• Diesel enhanced PHE degradation, while lubricant oil, catechol, salicylic, and phthalic acid inhibited it.

Conclusions:

• Microbial adaptation to PHE significantly enhances degradation capacity.
• PHE-acclimated soil is a promising inoculum for PAH bioremediation.
• Understanding co-contaminant effects is crucial for optimizing bioremediation strategies.