Current State of Knowledge in Microbial Degradation of Polycyclic Aromatic Hydrocarbons (PAHs): A Review

Abstract

Polycyclic aromatic hydrocarbons (PAHs) include a group of organic priority pollutants of critical environmental and public health concern due to their toxic, genotoxic, mutagenic and/or carcinogenic properties and their ubiquitous occurrence as well as recalcitrance. The increased awareness of their various adverse effects on ecosystem and human health has led to a dramatic increase in research aimed toward removing PAHs from the environment. PAHs may undergo adsorption, volatilization, photolysis, and chemical oxidation, although transformation by microorganisms is the major neutralization process of PAH-contaminated sites in an ecologically accepted manner. Microbial degradation of PAHs depends on various environmental conditions, such as nutrients, number and kind of the microorganisms, nature as well as chemical property of the PAH being degraded. A wide variety of bacterial, fungal and algal species have the potential to degrade/transform PAHs, among which bacteria and fungi mediated degradation has been studied most extensively. In last few decades microbial community analysis, biochemical pathway for PAHs degradation, gene organization, enzyme system, genetic regulation for PAH degradation have been explored in great detail. Although, xenobiotic-degrading microorganisms have incredible potential to restore contaminated environments inexpensively yet effectively, but new advancements are required to make such microbes effective and more powerful in removing those compounds, which were once thought to be recalcitrant. Recent analytical chemistry and genetic engineering tools might help to improve the efficiency of degradation of PAHs by microorganisms, and minimize uncertainties of successful bioremediation. However, appropriate implementation of the potential of naturally occurring microorganisms for field bioremediation could be considerably enhanced by optimizing certain factors such as bioavailability, adsorption and mass transfer of PAHs. The main purpose of this review is to provide an overview of current knowledge of bacteria, halophilic archaea, fungi and algae mediated degradation/transformation of PAHs. In addition, factors affecting PAHs degradation in the environment, recent advancement in genetic, genomic, proteomic and metabolomic techniques are also highlighted with an aim to facilitate the development of a new insight into the bioremediation of PAH in the environment.

Microbial responses to anthropogenic dissolved organic carbon in the Arctic and Antarctic coastal seawaters

“…1). Some compounds present in F2 are semi-labile, such as naphthalene and phenanthrene and can be respired by multiple groups of marine bacteria (Head et al, 2006;Ghosal et al, 2016). HNA showed similar trends as LNA but with a larger variability in the growth rates.…”

Detection and Quantification of Sulfate-Reducing and Polycyclic Aromatic Hydrocarbon-Degrading Bacteria in Oilfield Using Functional Markers and Quantitative PCR

“…Bacteria that can completely degrade or only transform polyaromatic hydrocarbons (PAH) are of particular interest due to the recalcitrance of PAH and accumulation in the environment [11,12]. Therefore, PAH-degraders can be applied for bioremediation of ecosystems polluted with crude oil or PAH.…”

“…Therefore, PAH-degraders can be applied for bioremediation of ecosystems polluted with crude oil or PAH. Moreover, they can be adopted for biological upgrading of heavy crude oil and refinery residues, which contain high proportions of aromatic compounds and asphaltenes, as well as for microbial enhanced oil recovery [5,11,13]. PAH-degrading bacteria can be isolated from oilfields and ecosystems polluted with PAH, crude oil, and fuels.…”

Pseudomonas sp. (Strain 10–1B): A potential inoculum candidate for green and sustainable remediation

“…The genome of Pseudomonas strain 10–1B predictably consisted of RHDs, various dioxygenases, ferredoxins, and reductases buttressing the ability of strain 10–1B to be potentially useful in PAH degradation. The dioxygenation (hydroxylation) step is very critical in the microbial degradation of any PAH (Cerniglia & Heitkamp, ; Ghosal, Ghosh, Dutta, & Ahn, ). Hydroxylation leads to the formation of a cis‐dihydrodiol that is transformed into some key intermediates, which are then subsequently metabolized.…”