Slow-Release Inoculation Allows Sustained Biodegradation of γ-Hexachlorocyclohexane

Mertens, Birgit; Boon, Nico; Verstraete, Willy

doi:10.1128/aem.72.1.622-627.2006

Cited by 43 publications

(20 citation statements)

References 35 publications

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“…The inoculum for bioaugmentation was prepared by cultivating PU-degrading fungal isolates on the surface of sterile wheat grains, which provided a convenient method for generating large quantities of biomass. Furthermore, it has been demonstrated that including a nutritive matrix along with a bioaugmenting inoculum can enhance degradation and survival of the inoculum (21). Addition of uninoculated wheat alone led to a 28% increase in PU degradation, probably due to the nutrients in the wheat, as the numbers of putative PU degraders in the soil and colonizing PU increased more than 35-fold.…”

Section: Discussionmentioning

confidence: 99%

Effect of Biostimulation and Bioaugmentation on Degradation of Polyurethane Buried in Soil

Cosgrove

McGeechan²,

Handley

et al. 2010

Appl Environ Microbiol

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This work investigated biostimulation and bioaugmentation as strategies for removing polyurethane (PU) waste in soil. Soil microcosms were biostimulated with the PU dispersion agent "Impranil" and/or yeast extract or were bioaugmented with PU-degrading fungi, and the degradation of subsequently buried PU was determined. Fungal communities in the soil and colonizing buried PU were enumerated on solid media and were analyzed using denaturing gradient gel electrophoresis (DGGE). Biostimulation with yeast extract alone or in conjunction with Impranil increased PU degradation 62% compared to the degradation in untreated control soil and was associated with a 45% increase in putative PU degraders colonizing PU. Specific fungi were enriched in soil following biostimulation; however, few of these fungi colonized the surface of buried PU. Fungi used for soil bioaugmentation were cultivated on the surface of sterile wheat to form a mycelium-rich inoculum. Wheat, when added alone to soil, increased PU degradation by 28%, suggesting that wheat biomass had a biostimulating effect. Addition of wheat colonized with Nectria haematococca, Penicillium viridicatum, Penicillium ochrochloron, or an unidentified Mucormycotina sp. increased PU degradation a further 30 to 70%, suggesting that biostimulation and bioaugmentation were operating in concert to enhance PU degradation. Interestingly, few of the inoculated fungi could be detected by DGGE in the soil or on the surface of the PU 4 weeks after inoculation. Bioaugmentation did, however, increase the numbers of indigenous PU-degrading fungi and caused an inoculum-dependent change in the composition of the native fungal populations, which may explain the increased degradation observed. These results demonstrate that both biostimulation and bioaugmentation may be viable tools for the remediation of environments contaminated with polyurethane waste.

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Section: Discussionmentioning

confidence: 99%

Effect of Biostimulation and Bioaugmentation on Degradation of Polyurethane Buried in Soil

Cosgrove

McGeechan²,

Handley

et al. 2010

Appl Environ Microbiol

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“…Genes involved in degradation (lin genes) have been isolated from aerobic bacteria and heterologously expressed, and the gene products have been characterized. We now have a reasonable understanding of the diversity, organization, and distribution of HCH catabolic genes in certain sphingomonads in particular (75), and there is growing interest from a variety of government, industry, and science agencies in using them to develop bioremediation technologies for the decontamination of HCH-contaminated sites (16,19,96,144). This article outlines our knowledge of the microbial degradation of HCH and discusses the issues surrounding the potential uses of the system for the bioremediation of HCH-contaminated sites.…”

Section: Fig 2 Known Locations Of Hch Dumps In Excess Ofmentioning

confidence: 99%

Biochemistry of Microbial Degradation of Hexachlorocyclohexane and Prospects for Bioremediation

Lal

Pandey

Sharma

et al. 2010

Microbiol Mol Biol Rev

352

338

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SUMMARY Lindane, the γ-isomer of hexachlorocyclohexane (HCH), is a potent insecticide. Purified lindane or unpurified mixtures of this and α-, β-, and δ-isomers of HCH were widely used as commercial insecticides in the last half of the 20th century. Large dumps of unused HCH isomers now constitute a major hazard because of their long residence times in soil and high nontarget toxicities. The major pathway for the aerobic degradation of HCH isomers in soil is the Lin pathway, and variants of this pathway will degrade all four of the HCH isomers although only slowly. Sequence differences in the primary LinA and LinB enzymes in the pathway play a key role in determining their ability to degrade the different isomers. LinA is a dehydrochlorinase, but little is known of its biochemistry. LinB is a hydrolytic dechlorinase that has been heterologously expressed and crystallized, and there is some understanding of the sequence-structure-function relationships underlying its substrate specificity and kinetics, although there are also some significant anomalies. The kinetics of some LinB variants are reported to be slow even for their preferred isomers. It is important to develop a better understanding of the biochemistries of the LinA and LinB variants and to use that knowledge to build better variants, because field trials of some bioremediation strategies based on the Lin pathway have yielded promising results but would not yet achieve economic levels of remediation.

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“…Xenobiotic compounds such as organochlorine pesticides constitute a major environmental problem due to their extensive use in the past, pronounced resistance to chemical and biological degradation (Miglioranza et al 2002) and their trend to bioaccumulate in the food chain (Mertens et al 2006). Contamination with halogenated aliphatic compounds is often considered to be relatively recalcitrant due to the gamma isomer of hexachlorocyclohexane (c-HCH or lindane).…”

Section: Introductionmentioning

confidence: 99%

Specific dechlorinase activity in lindane degradation by Streptomyces sp. M7

Cuozzo

Rollán

Abate

et al. 2009

World J Microbiol Biotechnol

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Synthesis of dechlorinase in Streptomyces sp. M7 was induced when the microorganism was grown in the presence of lindane (c-hexachlorocyclohexane) as the only carbon source. Activity of cells grown with lindane was about four and half times higher compared to cells grown with glucose. Maximum dechlorinase activity was observed at 30°C in alkaline conditions pH (7.9) and the enzyme did not show cation dependency. Sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed one differential band with a molecular weight similar to serum albumin (M r 66,200), which corresponded to polynucleotide phosphorylase, an enzyme that plays an important role in the regulation system and could be involved in the regulation of the dechlorinase gene. Detected in cell-free extracts were c-pentachlorocyclohexene and 1,3,4,6-tetrachloro-1,4-cyclohexadiene, both being products of the dechlorinase activity. This is the first time that the presence of an enzyme with dechlorinase activity has been demonstrated in an actinomycete strain isolated in Tucumán, Argentina. Characteristics of this enzyme revealed that Streptomyces sp. M7 could be useful in the future in bioremediation of soil or as a biosensor.

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Slow-Release Inoculation Allows Sustained Biodegradation of γ-Hexachlorocyclohexane

Cited by 43 publications

References 35 publications

Effect of Biostimulation and Bioaugmentation on Degradation of Polyurethane Buried in Soil

Effect of Biostimulation and Bioaugmentation on Degradation of Polyurethane Buried in Soil

Biochemistry of Microbial Degradation of Hexachlorocyclohexane and Prospects for Bioremediation

Specific dechlorinase activity in lindane degradation by Streptomyces sp. M7

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