Adding sodium dodecyl sulfate and Pseudomonas aeruginosa UG2 biosurfactants inhibits polycyclic aromatic hydrocarbon biodegradation in a weathered creosote-contaminated soil

Abstract

The effect of two anionic surfactants was assessed during biodegradation of 13 of the 16 USEPA priority polycyclic aromatic hydrocarbons (PAH) in a wood-preserving soil contaminated with creosote and pentacholorophenol for a period of at least 20 years. Sodium dodecyl sulfate (SDS) and biosurfactants from Pseudomonas aeruginosa UG2 were utilized at concentrations of 10, 100 and 500 micrograms/g soil. Because both surfactants are readily biodegradable, the microcosms received a fresh spike of surfactant every 2 weeks. Biodegradation of aged PAH residues was monitored by GC/MS for a period of 45 weeks. Results indicated that the biodegradation of the three-ring PAH was rapid and almost complete but was slowed by the addition of 100 micrograms/g and 500 micrograms/g chemical surfactant. Similarly, at the same concentrations, the two surfactants significantly decreased the biodegradation rate of the four-ring PAH. In this case, the inhibition was more pronounced with SDS. High-molecular-mass PAH (more than four rings) were not biodegraded under the test conditions. It was suggested that the preferential utilization of surfactants by PAH degraders was responsible for the inhibition observed in the biodegradation of the hydrocarbons. The high biodegradability and the inhibitory effect of these two surfactants would have a significant impact on the development of both above-ground and in situ site reclamation processes.

Federal Integrated Biotreatment Research Consortium (FIBRC): Flask to Field Initiative

“…The addition of biosurfactant stimulated indigenous bacteria to degrade hydrocarbons at higher rates than those achieved by nutrient addition alone (Atlas, 1993). Contradictory results are found in the literature concerning the effects of biosurfactants on PAH biodegradation Churchill et al, 1995;Deschenes et al, 1996;Finnerty, 1994;Miller, 1995;Providenti et al, 1995;Rocha and Infante, 1997;Volkering et al, 1998;Zhang and Miller, 1995). Many reports indicate that surfactants can enhance hydrocarbon biodegradation by increasing microbial accessibility to insoluble substrates (Zhang and Miller, 1994;Zhang et al, 1997).…”

Biodegradation of High-Molecular-Weight Polycyclic Aromatic Hydrocarbons by Bacteria

“…PAHs are present as natural constituents in fossil fuels, are formed during the incomplete combustion of organic material, and are therefore present in relatively high concentrations in products of fossil fuel refining (7,24,66,77,78,105,106). Petroleum refining and transport activities are major contributors to localized loadings of PAHs into the environment.…”

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

“…The water solubilities of most PAHs are in the lower parts-per-million range, and this is a major problem when studying and implementing aerobic degradation of PAHs. The use of surfactants may increase PAH solubility but may also be toxic to microorganisms (13,43). In some Arctic and temperate regions, soil temperature remains below 10°C year-round, and wet conditions limit oxygen availability.…”