Risk reductions during pyrene biotransformation and mobilization in a model plant-bacteria-biochar system

Area of Science:

• Environmental Science
• Microbiology
• Soil Science

Background:

• Bioremediation using microorganisms offers sustainable and cost-effective soil cleanup.
• Incomplete biodegradation and metabolite formation can increase soil toxicity during remediation.
• Motile bacteria may mobilize pollutants via biosorption, posing additional risks.

Purpose of the Study:

• To assess risks from cometabolism-based pyrene transformation by Pseudomonas putida G7.
• To identify strategies for minimizing risks during bioremediation.
• To evaluate the role of sunflower roots and biochar in pyrene mobilization and risk reduction.

Main Methods:

• Used 14C-labeled pyrene in a model soil system with Pseudomonas putida G7 and sunflower plants.
• Incorporated a biochar layer in some pots to trap mobilized pollutants and bacteria.
• Monitored pyrene biodegradation, metabolite mobilization, and bacterial movement.

Main Results:

• Sunflower plants enhanced pyrene biodegradation and metabolite mobilization through roots and percolate.
• Pots with plants showed increased bacterial mobilization towards the contamination source.
• The biochar layer effectively reduced pyrene metabolite concentrations in leachates.
• Combined application of plants, bacteria, and biochar significantly reduced overall risks.

Conclusions:

• Plant-microbe interactions can enhance bioremediation but may increase pollutant mobility.
• Biochar acts as an effective trap for pyrene metabolites and bacteria, mitigating risks.
• Integrating plants, motile bacteria, and biochar provides a safe and effective approach for soil remediation.