Polycyclic aromatic hydrocarbon-degrading bacteria in Anacostia River sediments: Presence and metabolic capabilities

Polycyclic Aromatic Hydrocarbons (PAHs) are universal, harmful, environmental contaminants capable of polluting soils and sediments for long periods of time, particularly in urban systems such as the Anacostia River. Many species of bacteria have been shown to degrade PAHs by using them as an energy source. Twenty-one strains representing three different regions (upstream, middle and downstream) of the Anacostia River system were capable of degrading either the PAHs or bezene, toluene and xylene (BTX) compounds, with many strains able to utilize multiple PAHs as the carbon source. Microbial community analysis using the WST-1 respiration indicator showed potential for utilization of all tested PAHs, with variation seen between sampling sites. PCR of the PAH-degrading gene familes tmoA, NDO, and nidA, showed a genetic capacity for PAH degradation at all sampling sites. DGGE revealed four types of tmoA genes, five types of NDO, and eight types of nidA-like genes in the Anacostia system. The presence of each type of gene differed between and within sampling sites, suggesting diverse potential for PAH-degradation in these soils.