Network Analysis for Prioritizing Biodegradation Metabolites of Polycyclic Aromatic Hydrocarbons

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are a diverse group of environmental contaminants released during the combustion of organic materials and the production and utilization of fossil fuels. Once released, PAHs deposit in soil and water bodies where they are subjected to environmental transport and transformations. As they degrade, intermediate transformation products may play an important role in their environmental impact. However, studying the effects of these degradation products has proven challenging because of the complexity, transience, and low concentration of many intermediates. Herein, a novel integration of a pathway prediction system and network theory was developed and applied to a set of four PAHs to demonstrate a possible solution to this challenge. Network analysis techniques were employed to refine the thousands of potential outputs and elucidate compounds of interest. Using these tools, we determined correlations between PAH degradation network data and intermediate metabolite structures, gaining information about the chemical characteristics of compounds based on their placement within the degradation network. Upon applying our developed filtering algorithm, we are able to predict up to 48% of the most common transformation products identified in a comprehensive empirical literature review. Additionally, our integrated approach uncovers potential metabolites which connect those found by past empirical studies but are currently undetected, thereby filling in the gaps of information in PAH degradation pathways.

Development of a highly efficient in‐tube solid‐phase microextraction system coupled with UHPLC‐MS/MS for analyzing trace hydroxyl polycyclic aromatic hydrocarbons in biological samples

“…Polycyclic aromatic hydrocarbons are globally considered to be hazardous substances, and are associated with reproductivity, development, hematotoxicity, carcinogenicity, cardiotoxicity, neurotoxicity, and immunotoxicity issues in humans and laboratory animals [1][2][3]. Polycyclic aromatic hydrocarbons are known to transform into hydroxyl polycyclic aromatic hydrocarbons (HPAHs) in biological systems, and free HPAHs are usually excreted in urine or feces in the form of conjugates with glucuronic acid or sulfate.…”

Fast Location and Isolation of Phenanthrene-degrading Halophilic Microbial Community and its Degradation Pathway

“…In the process of aerobic PHE degradation, the cracking of a benzene ring usually starts from the hydroxyl containing benzene ring 13 . According to previous studies, the biodegradation of PHE usually through the double hydroxylation of the C1-C2 pathway or C3-C4 pathway 20,21 . In the C1-C2 pathway, dihydroxylation occured at C1 and C2 carbon sites.…”

A Classification Model to Identify Direct-Acting Mutagenic Polycyclic Aromatic Hydrocarbon Transformation Products

“…6,7 During their time in the aerobic region of soil and/or water, PAHs can form a multitude of different transformation products (TPs), many of which are hazardous. 8,9 The U.S. Environmental Protection Agency (EPA) currently classifies 16 PAHs as priority pollutants. 10 While these compounds have been well studied, there is limited research that examines the hazard of TPs that result from PAH biodegradation, which occurs naturally in the environment and can also be induced with deliberate bioremediation at contaminated sites.…”

“…Polycyclic aromatic hydrocarbons (PAHs) contain at least two aromatic rings and are the byproduct of both natural and industrial pyrogenic processes, including forest fires, extraction and burning of fossil fuels, plastic manufacturing, and municipal waste incineration. , Consequently, PAHs can be found in all environmental compartmentsthe atmosphere, soil, and water . Atmospheric deposition of PAHs occurs within a few days of emission, , and some PAHs can persist for up to several months on surface soils or in water as they slowly degrade. , During their time in the aerobic region of soil and/or water, PAHs can form a multitude of different transformation products (TPs), many of which are hazardous. , …”

“…While these compounds have been well studied, there is limited research that examines the hazard of TPs that result from PAH biodegradation, which occurs naturally in the environment and can also be induced with deliberate bioremediation at contaminated sites. While biodegradation typically eliminates the original unsubstituted PAHs, it does not necessarily eliminate health risks due to their toxic TPs. − Tools have been developed to aid in the prediction of likely transformation products, some based on empirically observed relationships and some theoretical. ,− However, there is still a need for improved methods of evaluating various forms of toxicity of these predicted and experimentally observed structures, for which few data exist. Numerous studies have noted that PAH TPs exhibit greater developmental toxicity, mutagenicity, or genotoxicity than the original PAHs, including PAHs of lower molecular weight, containing three rings or fewer. ,− Furthermore, previous studies suggest that there are multiple possible mechanisms by which small hydrocarbons may exhibit mutagenicity. − …”