Kinetics of biodegradation of binary and ternary mixtures of PAHs

Abstract

The kinetics of biodegradation of mixtures of polycyclic aromatic hydrocarbons (PAHs) by Sphingomonas paucimobilis strain EPA505 were investigated. The investigation focused on three- and four-ring PAHs, specifically 2-methylphenanthrene, fluoranthene, and pyrene. Uptake rates in aerobic batch suspended cultivations were measured for the individual PAHs and their binary and ternary mixtures. It was observed that kinetics were influenced by the mixture composition and the kinetic properties of the components. A material balance equation containing the Monod model was numerically fitted to uptake data to determine extant kinetic parameters for the individual PAHs. Similarly, equations containing kinetic interaction models derived from enzyme kinetics were fitted to the uptake data obtained from experiments with binary and ternary mixtures. The investigation considered the following interaction types: no-interaction (Monod), pure competitive interaction, noncompetitive or mixed-type interaction, uncompetitive inhibition, and nonspecific interaction based on pure competition (SKIP). Model fit was evaluated based on probabilistic and statistical criteria and inferences were reached about underlying interaction mechanisms based on model fit. Mixture kinetics were most adequately simulated by the pure competitive interaction model with mutual substrate exclusivity. This model is fully predictive, relying only on parameters determined in the sole-PAH experiments. It was shown that for low percent inhibition values and with limited data, pure competitive interaction kinetics may not be evident, resembling no-interaction kinetics. This study is a reasonable starting point for understanding and modeling biodegradation of complex PAH mixtures in engineered and natural systems.

A new model for the biodegradation kinetics of oil droplets: application to the Deepwater Horizon oil spill in the Gulf of Mexico

“…For BTEX, a μ max value of 0.32 h -1 and a K s value of 129.2 mg/L was used based on averaged values from literature data [16,43-47]. For PAHs, μ max and K s values of 0.053 h -1 and 28.65 mg/L were used, respectively [32,48]. From the initial and final concentrations reported for the biodegradation of oil spilled in the Gulf of Mexico [7], we calculated the yield coefficient to be equeal to1.25 × 10 8 cells/mg-oil.…”

Multisubstrate kinetics of PAH mixture biodegradation: analysis in the double-logarithmic plot

“…In contrast to most of the previous studies of the kinetics of PAH mixture conversion (Guha et al 1999;Knightes and Peters 2006;Dimitriou-Christidis and Autenrieth 2007;Desai et al 2008), in this work we have concentrated our attention on the direct analysis of the curves of PAH mixture conversion without resorting to sole-substrate experiments. We have shown theoretically that in the case of multisubstrate Figure b shows the data on conversion of the PHE-FLA pair in the subsequent experiment (cross) kinetics with a common active site the logarithms of substrate concentrations are linearly dependent.…”

“…In most cases, aqueous-phase PAH mixture conversion can be satisfactorily described by a multisubstrate model, according to which all mixture components compete for the same common active site in accordance with the principles of Michaelis kinetics (Stringfellow and Aitken 1995;Guha et al 1999;Lotfabad and Gray 2002;Knightes and Peters 2006;Dimitriou-Christidis and Autenrieth 2007;Desai et al 2008).…”

Modeling sorption and biodegradation of phenanthrene in mangrove sediment slurry

“…Based on the Monod equation, some other models were also developed for the PAH biodegradation process [11,13]. A complicated model, including the microbial biodegradation activity of the PAHs in the aqueous phase and PAHs sorption kinetics with respect to the organic carbon content, was developed by ArtolaGaricano et al [14].…”

“…To model the biodegradation process, a non-linear model, namely the Monod equation, is commonly used to describe the kinetics of biodegradation of organic compounds such as PAHs [10][11][12]. Based on the Monod equation, some other models were also developed for the PAH biodegradation process [11,13].…”