Biodegradation of aromatic hydrocarbons in an extremely acidic environment

Area of Science:

• Environmental microbiology
• Bioremediation
• Aromatic hydrocarbon degradation

Background:

• Coal pile runoff creates acidic soil environments (pH 2.0).
• Indigenous soil microbes can degrade aromatic hydrocarbons like naphthalene and toluene.
• Previous studies often focus on neutrophilic bacteria for hydrocarbon degradation.

Purpose of the Study:

• To assess the biodegradation potential of aromatic hydrocarbons in low-pH soils.
• To investigate the microbial mechanisms involved in hydrocarbon degradation under acidic conditions.
• To identify the microbial communities responsible for pollutant remediation.

Main Methods:

• Soil sampling along contaminant and pH gradients.
• Measurement of hydrocarbon mineralization to CO2.
• DNA hybridization analysis to identify microbial genes.
• Culturing and testing of isolated microbial consortia.

Main Results:

• Microbial communities at pH 2.0 actively degraded over 40% of naphthalene and toluene.
• Cycloheximide treatment inhibited this degradation, suggesting microbial involvement.
• DNA analysis revealed no common neutrophilic bacterial genes, indicating unique degradation pathways.
• An undefined mixed culture (fungi, yeast, bacteria) metabolized 27% of naphthalene in one week.

Conclusions:

• Biodegradation of aromatic hydrocarbons is feasible in extremely acidic environments.
• Microbial consortia, including fungi and yeast, play a significant role in low-pH hydrocarbon remediation.
• This finding expands our understanding of microbial resilience and bioremediation strategies in contaminated soils.