Compound degraded:Polychlorinated naphthalene
General Description (About POP compound)
Polychlorinated naphthalene (PCN) are the products obtained upon treatment of naphthalene with chlorine. There are 75 possible congeners of chlorinated naphthalenes. Commercial products are generally mixtures of several congeners and range from thin liquids to hard waxes to high melting point solids. Their main uses have been in cable insulation, wood preservation, engine oil additives, electroplating masking compounds, capacitors, and refractive index testing oils and as a feedstock for dye production.
Biodegradation pathway
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Publications
| Abstract | Title | Authors | Article Link |
|---|---|---|---|
| There is increasing concern regarding the adverse health effects of polychlorinated naphthalenes (PCNs). The metabolic degradation of 1,4-dichloronaphthalene (1,4-DCN) as a model PCN, was studied using a strain of Pseudomonas sp. HY. The metabolites were analyzed by gas chromatography-mass spectrometry (GC-MS). A series of metabolites including dihydroxy-dichloro-naphthalene, epoxy-dichlorinated naphthalene, dichlorinated naphthol, and dichlorinated salicylic acid were identified. The time-concentration plots of the degradation curves of 1,4-DCN was also obtained from the experiments, which set the initial concentration of 1,4-DCN to 10 mg/L and 20 mg/L, respectively. The results showed that 98% removal could be achieved within 48 h at an initial 1,4-DCN concentration of 10 mg/L. Nevertheless, it took 144 h to reach the same degradation efficiency at an initial concentration of 20 mg/L. The degradation of 1,4-DCN may not remove the chloride ions during the processes and the metabolites may not benefit the bacterial growth. The research suggests a metabolic pathway of 1,4-DCN, which is critical for the treatment of this compound through biological processes. | Metabolic Degradation of 1,4-dichloronaphthalene by Pseudomonas sp. HY | Yu et al., 2015 | Link |
| Influence of current circulation and sewage sludge on spatial distributions of polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs), and polybrominated diphenyl ethers (PBDEs) in sediments and mussels from the Qingdao coastal sea were investigated. Total concentrations of PCBs, PCNs and PBDEs in sediments ranged 6.5–32.9, 0.2–1.2, and 0.1–5.5 ng g?1 dry wt, respectively. The maximum concentrations were all found near the Haibo River mouth, affected by sewage sludge input from the river. Under the current system in Jiaozhou Bay the organic pollutants were subject to deposit on the east side of the bay and trapped inside the bay. Sewage sludge was an important source of PCBs, PCNs and PBDEs in the bay and exponentially magnified the enrichment of PCBs. On the other hand, the congener profiles of PCBs in sediments outside the bay may signify an atmospheric source of PCBs. Total Concentrations of PCBs, PCNs and PBDEs in mussels were 61.4–88.6, 9.0, and 13.8 ng g?1 lipid, respectively. Mussels enriched significantly PCBs, PCNs and PBDEs relative to the sediments. The total toxicity equivalent quantities (TEQs) of PCNs in mussels were generally lower than that of PCBs. The fluxes of the total PCBs and their TEQs have been decreased steadily since 1950s. The lower chlorinated/brominated congeners of PCNs and PBDEs may exhibit a greater tendency due to less lipophilic and thus a greater probability of being affected by the current circulation in the bay. | PCBs, PCNs and PBDEs in sediments and mussels from Qingdao coastal sea in the frame of current circulations and influence of sewage sludge | Pan et al., 2007 | Link |
| Biodegradation of the polychlorinated naphthalenes (PCNs) 1,4-dichloronaphthalene (1,4-DCN), 2,7-dichloronaphthalene (2,7-DCN), and 1,2,3,4-tetrachloronaphthalene (1,2,3,4-TCN), by the white-rot fungus Phlebia lindtneri was investigated. 1,4-DCN was metabolized to form six metabolites by the fungus. It was estimated from GC–MS fragment patterns that the metabolites were four putative hydroxylated and two dihydrodihydroxylated compounds. One of the hydroxylated products was identified as 2,4-dichloro-1-naphthol by GC–MS analysis using an authentic standard. This intermediate indicated chlorine migration in a biological system of P. lindtneri. 2,7-DCN was metabolized to five hydroxylated metabolites and a dihydrodihydroxylated metabolite. Significant inhibition of the degradation of DCNs and formation of their metabolic products was observed in incubation with the cytochrome P-450 monooxygenase inhibitor piperonyl butoxide. The formation of the dihydrodiol-like metabolites, chlorine migration and the experiment with P-450 inhibitor suggested that P. lindtneri provides hydroxyl metabolites via benzene oxide intermediates of DCNs by a cytochrome P450 monooxygenase. In addition, P. lindtneri degraded 1,2,3,4-TCN; two hydroxylated compounds and a dihydrodihydroxylated compound were formed. | Fungal hydroxylation of polychlorinated naphthalenes with chlorine migration by wood rotting fungi | Mori et al., 2009 | Link |
| 1-Chloronaphthalene and 2-chloronaphthalene were metabolized by pseudomonads able to degrade naphthalene, but the chloronaphthalenes did not support growth. Their metabolism probably proceeded by the pathway for naphthalene metabolism, for they were not metabolized by cured derivatives of strains in which naphthalene metabolism is normally determined by a plasmid, the metabolism of 2-chloronaphthalene was accompanied by the accumulation of a chloro-2-hydroxy-6-oxohexadienoate, and 4- and 5-chlorosalicylate were converted to this compound and themselves induced enzymes for naphthalene and chloronaphthalene metabolism. In one strain, ATCC 17483, it was possible to show that during growth on succinate in the presence of chloronaphthalenes the enzymes of naphthalene metabolism were induced. Failure of 2-chloronaphthalene to support growth was probably associated with the very slow metabolism of the chloro-2-hydroxy-6-oxohexadienoic acid or possibly with the toxicity of this compound or its metabolites. | The cometabolism of 1- and 2-chloronaphthalene by pseudomonads | Morris and Barnsley. 1982 | Link |
| Pseudomonas putida expresses plasmid-encoded enzymes and regulatory proteins for the dissimilation of naphthalene through salicylate and the alpha-keto acid pathway. A strain of P. putida (NAH:Tn5/G67) defective in salicylate hydroxylase (nahG) was assessed for its ability to oxidize 1,4-dichloronaphthalene. Washed cell suspensions were shown to accumulate 3,6-dichlorosalicylate, which, after further chemical treatment, yields the herbicide dicamba (3,6-dichloro-2-methoxybenzoate). However, the rate of dichlorosalicylate formation from dichloronaphthalene was less than 1% of the rate of salicylate formation from unsubstituted naphthalene. | Recruitment of naphthalene dissimilatory enzymes for the oxidation of 1,4-dichloronaphthalene to 3,6-dichlorosalicylate, a precursor for the herbicide dicamba | Durham and Stewart. 1987 | Link |
| Poly- and perfluorinated chemicals, including perfluorinated alkyl substances (PFAS), are pervasive in today’s society, with a negative impact on human and ecosystem health continually emerging. These chemicals are now subject to strict government regulations, leading to costly environmental remediation efforts. Commercial polyfluorinated compounds have been called ‘forever chemicals’ due to their strong resistance to biological and chemical degradation. Environmental cleanup by bioremediation is not considered practical currently. Implementation of bioremediation will require uncovering and understanding the rare microbial successes in degrading these compounds. This review discusses the underlying reasons why microbial degradation of heavily fluorinated compounds is rare. Fluorinated and chlorinated compounds are very different with respect to chemistry and microbial physiology. Moreover, the end product of biodegradation, fluoride, is much more toxic than chloride. It is imperative to understand these limitations, and elucidate physiological mechanisms of defluorination, in order to better discover, study, and engineer bacteria that can efficiently degrade polyfluorinated compounds. | Nothing lasts forever: understanding microbial biodegradation of polyfluorinated compounds and perfluorinated alkyl substances | Wackett. 2021 | Link |
| Thousands of heavily fluorinated chemicals are found in the environment, impact human and ecosystem health, and are relatively resistant to biological and chemical degradation. Their persistence in the environment is due to the inability of most microorganisms to biodegrade them. Only a very few examples of polyfluorinated compound biodegradation are known, and the reported rates are very low. This has been mostly attributed to the low chemical reactivity of the C-F bond. This Perspective goes beyond that explanation to highlight microbiological reasons why polyfluorinated compounds resist metabolism. The evolutionary and physiological impediments must be appreciated to better find, study, and harness microbes that degrade polyfluorinated compounds. | Why Is the Biodegradation of Polyfluorinated Compounds So Rare? | Wackett. 2021 | Link |