Degradation of Polycyclic Aromatic Hydrocarbons at Low Temperature under Aerobic and Nitrate-Reducing Conditions in Enrichment Cultures from Northern Soils

Abstract

The potential for biodegradation of polycyclic aromatic hydrocarbons (PAHs) at low temperature and under anaerobic conditions is not well understood, but such biodegradation would be very useful for remediation of polluted sites. Biodegradation of a mixture of 11 different PAHs with two to five aromatic rings, each at a concentration of 10 g/ml, was studied in enrichment cultures inoculated with samples of four northern soils. Under aerobic conditions, low temperature severely limited PAH biodegradation. After 90 days, aerobic cultures at 20°C removed 52 to 88% of the PAHs. The most extensive PAH degradation under aerobic conditions at 7°C, 53% removal, occurred in a culture from creosote-contaminated soil. Low temperature did not substantially limit PAH biodegradation under nitrate-reducing conditions. Under nitrate-reducing conditions, naphthalene, 2-methylnaphthalene, fluorene, and phenanthrene were degraded. The most extensive PAH degradation under nitrate-reducing conditions at 7°C, 39% removal, occurred in a culture from fuel-contaminated Arctic soil. In separate transfer cultures from the above Arctic soil, incubated anaerobically at 7°C, removal of 2-methylnaphthalene and fluorene was stoichiometrically coupled to nitrate removal. Ribosomal intergenic spacer analysis suggested that enrichment resulted in a few predominant bacterial populations, including members of the genera Acidovorax, Bordetella, Pseudomonas, Sphingomonas, and Variovorax. Predominant populations from different soils often included phylotypes with nearly identical partial 16S rRNA gene sequences (i.e., same genus) but never included phylotypes with identical ribosomal intergenic spacers (i.e., different species or subspecies). The composition of the enriched communities appeared to be more affected by presence of oxygen, than by temperature or source of the inoculum.

Remarkable impact of PAHs and TPHs on the richness and diversity of bacterial species in surface soils exposed to long-term hydrocarbon pollution

“…naphthalene, n-dod. n-dodecane (Skowasch et al 2002;Erikson et al 2003;Pannu et al 2003;Singleton et al 2009). T-RFs of 72 bp (39.59 %), 147 bp (14.87 %) and 153 bp (20.36 bp) represented 74.75 % of the total relative abundance in highly PAH impacted sample SCS.…”

Utility of lipid biomarkers in support of bioremediation efforts at army sites

“…Burkholderia was one of the more abundant species detected in our tests. Strains of the beta-proteobacteria Bordettella and the gammaproteobacteria Pseudomonas stutzeri are capable of degrading a variety of contaminants, including aromatic compounds (Eriksson et al, 2003;Spanggord et al, 1991). In short, the unsaturated soil fostered the development of a diverse community with biodegradative capabilities.…”

Bioremediation Approaches for Treating Low Concentrations of N-Nitrosodimethylamine in Groundwater

“…To support nitrate-reducing conditions, a nitrogen-free basal salts medium was amended with 0.75 g/L potassium nitrate as the electron acceptor (Eriksson et al, 2003).…”