Molinate biodegradation in soils: natural attenuation versus bioaugmentation

Area of Science:

• Environmental microbiology
• Bioremediation science
• Soil science

Background:

• Molinate is a herbicide commonly found in paddy field soils.
• Contamination of soil with molinate poses environmental risks.
• Bioremediation offers a sustainable approach to decontaminate soils.

Purpose of the Study:

• To evaluate natural attenuation and bioaugmentation for reducing molinate soil contamination.
• To assess the impact of these bioremediation strategies on soil indigenous microbiota.
• To compare the efficacy of bioaugmentation versus natural attenuation.

Main Methods:

• Microcosm experiments were conducted using paddy field soils.
• Bioaugmentation involved inoculation with a molinate-mineralizing mixed culture (DC).
• Molinate concentrations and microbial community structure (16S rRNA DGGE) were analyzed.

Main Results:

• Bioaugmentation achieved significantly higher molinate removal (63%) than natural attenuation (39%) after 42 days.
• The gene for molinate breakdown was detected in bioaugmented microcosms, linked to Gulosibacter molinativorax ON4(T).
• Neither bioaugmentation nor natural attenuation significantly altered the soil bacterial community structure.

Conclusions:

• Bioaugmentation with mixed culture DC is a more effective strategy for molinate removal than natural attenuation.
• Both methods can reduce molinate contamination without perturbing the indigenous microbiota.
• The study highlights the potential of targeted microbial inoculation for soil remediation.