Biodegradation kinetics of select polycyclic aromatic hydrocarbon (PAH) mixtures by Sphingomonas paucimobilis EPA505

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• 作者：Anuradha M. Desai ; Robin L. Autenrieth ; Petros Dimitriou-Christidis and Thomas J. McDonald
• 关键词：PAHs ; Biodegradation kinetics ; Mixtures ; Substrate interactions ; Monod parameters ; Multisubstrate
• 刊名：Biodegradation
• 出版年：2008
• 出版时间：April, 2008
• 年：2008
• 卷：19
• 期：2
• 页码：223-233
• 全文大小：327.3 KB
• 刊物类别：Earth and Environmental Science
• 刊物主题：Environment
  Soil Science and Conservation
  Geochemistry
  Terrestrial Pollution
  Waste Water Technology, Water Pollution Control, Water Management and Aquatic Pollution
  Waste Management and Waste Technology
  
• 出版者：Springer Netherlands
• ISSN：1572-9729

文摘

Many contaminated sites commonly have complex mixtures of polycyclic aromatic hydrocarbons (PAHs) whose individual microbial biodegradation may be altered in mixtures. Biodegradation kinetics for fluorene, naphthalene, 1,5-dimethylnaphthalene and 1-methylfluorene were evaluated in sole substrate, binary and ternary systems using Sphingomonas paucimobilis EPA505. The first order rate constants for fluorene, naphthalene, 1,5-dimethylnaphthalene, and 1-methylfluorene were comparable; yet Monod parameters were significantly different for the tested PAHs. S. paucimobilis completely degraded all the components in binary and ternary mixtures; however, the initial degradation rates of individual components decreased in the presence of competitive PAHs. Results from the mixture experiments indicate competitive interactions, demonstrated mathematically. The generated model appropriately predicted the biodegradation kinetics in mixtures using parameter estimates from the sole substrate experiments, validating the hypothesis of a common rate-determining step. Biodegradation kinetics in mixtures were affected by the affinity coefficients of the co-occurring PAHs and mixture composition. Experiments with equal concentrations of substrates demonstrated the effect of concentration on competitive inhibition. Ternary experiments with naphthalene, 1,5-dimethylnaphthalene and 1-methylfluorene revealed delayed degradation, where depletion of naphthalene and 1,5-dimethylnapthalene occurred rapidly only after the complete removal of 1-methylfluorene. The substrate interactions observed in mixtures require a multisubstrate model to account for simultaneous degradation of substrates. PAH contaminated sites are far more complex than even ternary mixtures; however these studies clearly demonstrate the effect that interactions can have on individual chemical kinetics. Consequently, predicting natural or enhanced degradation of PAHs cannot be based on single compound kinetics as this assumption would likely overestimate the rate of disappearance.