Investigations of Enzymatic Alterations of 2,4-Dichlorophenol Using 13c-Nuclear Magnetic Resonance in Combination With Site-Specific 13c-Labeling: Understanding the Environmental Fate of This Pollutant

Nanny, Mark A.; Bortiatynski, Jacqueline M.; Hatcher, Patrick G.

doi:10.1897/1551-5028(1996)015<1857:ioeaod>2.3.co;2

Cited by 3 publications

(2 citation statements)

References 24 publications

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“…Laccases can transform guaiacol, 1-naphthol, and vanillic acid into oligomeric products (dimers to pentamers) (33). In vitro experiments have revealed enzymatic covalent binding of aromatic xenobiotic compounds (2,4-dichlorophenol and pentachlorophenol) to humic acid or FA (21,26). This binding demonstrates the importance of the oxidative coupling reaction (detoxification) and repolymerization in the environment (7,20).…”

Section: Discussionmentioning

confidence: 98%

Purification and Characterization of Laccase from Chaetomium thermophilium and Its Role in Humification

Chefetz¹,

Chen²,

Hadar

1998

Appl Environ Microbiol

246

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Chaetomium thermophilium was isolated from composting municipal solid waste during the thermophilic stage of the process.C. thermophilium, a cellulolytic fungus, exhibited laccase activity when it was grown at 45°C both in solid media and in liquid media. Laccase activity reached a peak after 24 h in liquid shake culture. Laccase was purified by ultrafiltration, anion-exchange chromatography, and affinity chromatography. The purified enzyme was identified as a glycoprotein with a molecular mass of 77 kDa and an isoelectric point of 5.1. The laccase was stable for 1 h at 70°C and had half-lives of 24 and 12 h at 40 and 50°C, respectively. The enzyme was stable at pH 5 to 10, and the optimum pH for enzyme activity was 6. The purified laccase efficiently catalyzed a wide range of phenolic substrates but not tyrosine. The highest levels of affinity were the levels of affinity to syringaldazine and hydroxyquinone. The UV-visible light spectrum of the purified laccase had a peak at 604 nm (i.e., Cu type I), and the activity was strongly inhibited by Cu-chelating agents. When the hydrophobic acid fraction (the humic fraction of the water-soluble organic matter obtained from municipal solid waste compost) was added to a reaction assay mixture containing laccase and guaiacol, polymerization took place and a soluble polymer was formed. C. thermophilium laccase, which is produced during the thermophilic stage of composting, can remain active for a long period of time at high temperatures and alkaline pH values, and we suggest that this enzyme is involved in the humification process during composting.

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Section: Discussionmentioning

confidence: 98%

Purification and Characterization of Laccase from Chaetomium thermophilium and Its Role in Humification

Chefetz¹,

Chen²,

Hadar

1998

Appl Environ Microbiol

246

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“…and Burkholderia sp. (Bengtsson and Carlsson, 2001;Shaw et al, 2002), and by eukaryotes, such as the white-rot fungus Phanerochaete chrysosporium (Nanny et al, 1996). Fewer organisms can mineralize 2,4-DCP and this process may be more sensitive to a decrease in biomass.…”

Section: Time (Weeks) Time (Weeks)mentioning

confidence: 99%

Bacterial diversity promotes community stability and functional resilience after perturbation

Girvan

Campbell²,

Killham

et al. 2005

Environmental Microbiology

451

239

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The relationships between bacterial community diversity and stability were investigated by perturbing soils, with naturally differing levels of diversity, to equivalent toxicity using copper sulfate and benzene. Benzene amendment led to large decreases in total bacterial numbers and biomass in both soils. Benzene amendment of an organo-mineral/improved pasture soil altered total soil bacterial community structure but, unlike amendment of the mineral/arable soil, maintained genetic diversity, based on polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis targeting DNA and RNA, until week 9 of the perturbation experiment. Assuming equivalent toxicity, the genetic diversity of the naturally more diverse soil was more resistant to benzene perturbation than the less diverse soil. The broad scale function (mineralization of 14C-labelled wheat shoot) of both benzene- and copper-treated soil communities was unaffected. However, narrow niche function (mineralization of 14C-labelled 2,4-dichlorophenol) was impaired for both benzene-polluted soils. The organo-mineral soil recovered this function by the end of the experiment but the mineral soil did not, suggesting greater resilience in the more diverse soil. Despite a large reduction in bacterial numbers and biomass in the copper-treated soils, only small differences in bacterial community diversity were observed by week 9 in the copper-polluted soils. The overall community structure was little altered and functionality, measured by mineralization rates, remained unchanged. This suggested a non-selective pressure and a degree of genetic and functional resistance to copper perturbation, despite a significant reduction in bacterial numbers and biomass. However, initial shifts in physiological profiles of both copper-polluted soils were observed but rapidly returned to those of the controls. This apparent functional recovery, accompanied by an increase in culturability, possibly reflects adaptation by the surviving communities to perturbation. The findings indicate that, although soil communities may be robust, relationships between diversity and stability need to be considered in developing a predictive understanding of response to environmental perturbations.

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Isolation and characterization of a micromycete, a producer of neutral catechol oxidases, from tropical soils with elevated dioxine content

Vasil'chenko

Королева

Степанова

et al. 2000

Appl Biochem Microbiol

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Investigations of Enzymatic Alterations of 2,4-Dichlorophenol Using 13c-Nuclear Magnetic Resonance in Combination With Site-Specific 13c-Labeling: Understanding the Environmental Fate of This Pollutant

Cited by 3 publications

References 24 publications

Purification and Characterization of Laccase from Chaetomium thermophilium and Its Role in Humification

Purification and Characterization of Laccase from Chaetomium thermophilium and Its Role in Humification

Bacterial diversity promotes community stability and functional resilience after perturbation

Isolation and characterization of a micromycete, a producer of neutral catechol oxidases, from tropical soils with elevated dioxine content

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