Methanotrophic Bacteria: Use in Bioremediation
15 Jan 2003-
TL;DR: The methanotrophic bacteria that oxidize methane as an energy source and carbon source through the enzyme methane monooxygenase (MMO) can cometabolize or transform nongrowth substrates by either growing or resting cells as discussed by the authors.
Abstract: The methanotrophs are aerobic bacteria that oxidize methane as an energy source and carbon source through the enzyme methane monooxygenase (MMO). This MMO can cometabolize or transform nongrowth substrates by either growing or resting cells. Cometabolism is a result of nonspecific MMO activity towards organic compounds that do not serve as carbon or energy sources. While many cometabolizing bacterial species have been identified, the best studied are the methanotrophs. The reason for this is that methanotrophs are ubiquitous and can cometabolize many aliphatic compounds, alkanes, and aromatic compounds. Methanotrophs have been intensely studied for use in degrading chlorinated solvents, most notably trichloroethylene, to environmentally acceptable concentrations in soils, sediment, and groundwater. Stimulation of methanotrophic bacteria is accomplished through the addition of methane and other gaseous nutrients resulting in an increase in contaminant biodegradation and biotransformation. The composition of gaseous nutrients used with methane is dependent on the characteristics of the site geochemistry and microbiology. This biostimulation may be applied in situ within the contaminated aquifer or soil. If necessary, the contaminated soil or groundwater can be moved and treated ex situ based on the site-specific needs.
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TL;DR: Metabolism of VC and ethene by strains AJ and TD is initiated by an alkene monooxygenase, and this process occurs at many but not all sites where groundwater is contaminated with chloroethenes.
Abstract: Pseudomonas putida strain AJ and Ochrobactrum strain TD were isolated from hazardous waste sites based on their ability to use vinyl chloride (VC) as the sole source of carbon and energy under aerobic conditions. Strains AJ and TD also use ethene and ethylene oxide as growth substrates. Strain AJ contained a linear megaplasmid (approximately 260 kb) when grown on VC or ethene, but it contained no circular plasmids. While strain AJ was growing on ethylene oxide, it was observed to contain a 100-kb linear plasmid, and its ability to use VC as a substrate was retained. The linear plasmids in strain AJ were cured, and the ability of strain AJ to consume VC, ethene, and ethylene oxide was lost following growth on a rich substrate (Luria-Bertani broth) through at least three transfers. Strain TD contained three linear plasmids, ranging in size from approximately 90 kb to 320 kb, when growing on VC or ethene. As with strain AJ, the linear plasmids in strain TD were cured following growth on Luria-Bertani broth and its ability to consume VC and ethene was lost. Further analysis of these linear plasmids may help reveal the pathway for VC biodegradation in strains AJ and TD and explain why this process occurs at many but not all sites where groundwater is contaminated with chloroethenes. Metabolism of VC and ethene by strains AJ and TD is initiated by an alkene monooxygenase. Their yields during growth on VC (0.15 to 0.20 mg of total suspended solids per mg of VC) are similar to the yields reported for other isolates (i.e., Mycobacterium sp., Nocardioides sp., and Pseudomonas sp.).
115 citations
TL;DR: In insights into the effects of halogenated fungicide application and bioaugmentation on indigenous soil microbiomes, little influence on soil microbial community was observed for each inoculation treatment, showing that TPN treatment is the main force for the shift in indigenous consortia.
35 citations
Cites background from "Methanotrophic Bacteria: Use in Bio..."
...Sphingomonas, Methylotenera, Acidovorax and Methylibium species were also reported for degradation of chlorinated aromatic herbicides [60], chlorinated solvents [61], chlorinated aromatic hydrocarbons and haloacids [62,63]....
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TL;DR: This discussion is focused on methanotrohphic bacterial population dynamics observed during growth on various copper species, to extrapolate their impact on geomicrobiological processes.
Abstract: Two distinct enzymatic pathways are implicated in the key step whereby methane is converted to methanol by the aerobic methane oxidizing bacteria (methanotrophs). These two enzymes, soluble and particulate methane monooxygenases (sMMO and pMMO, respectively), are evolutionarily unrelated. However, the activities of these enzymes are tightly linked to copper, which is central to the switch responsible for regulating MMO expression. When bioavailable copper exceeds a certain threshold relative to cell biomass, pMMO is expressed and its activity maintained by available copper. Below this threshold or when copper is entirely absent, sMMO catalyses methane oxidation. The individual forms of MMO degrade methane and hydrocarbon pollutants at different rates and efficiencies. Typically, pMMO is by up to 30% more efficient at methane degradation as opposed to sMMO which is more effective in the transformation of a wide range of hazardous hydrocarbons than pMMO. Consequently, the type of MMO expressed influences th...
21 citations
01 Jan 2016
TL;DR: In this article, the authors investigated the impact of industrial xenobiotics on soil microbial communities and their functional capabilities, with particular focus on widely used pesticides (chlorpyrifos and imidacloprid) and industrial solvents (trichloroethene).
Abstract: Excessive use and lack of appropriate disposal technology for industrial xenobiotics have resulted in the contamination of ecosystems globally impacting the selfregulating capacity of the biosphere. This often results in irreversible alterations of ecosystem’s structure and function, but the outcomes of these events on soil microbial communities (and their functional capabilities) are poorly understood. Assessing the impact of xenobiotics on soil microbial communities is of paramount importance as they play a vital role in ecosystem services and maintain soil health, which are key requirements for sustainable land use in terms of food security and environmental sustainability. Bacteria are the most abundant and diverse soil microflora and play a key role in the biogeochemical cycles of important elements including carbon (C), nitrogen (N), and phosphorus (P) and sulphur (S). The current work aimed to unravel the two-way interactions between xenobiotics and soil microbial communities; i.e., how soil microbial communities modulate xenobiotic persistence through biodegradation and what impacts xenobiotic have on soil microbial community’s structure and functions, with particular focus on widely used pesticides (chlorpyrifos and imidacloprid) and industrial solvents (trichloroethene) In Chapter 2, characterisation of active methanotrophs involved in trichloroethene (TCE) degradation under different methane (CH4) concentrations was evaluated. Methane (CH4) enriched methanotrophic consortia from three Australian soils (Sydney University, Victoria Park and Botany Industrial Park) were examined for their effectiveness in TCE (50μM) degradation at 1%, 10% and 33% CH4 concentration at 20C. Only the methanotrophic consortium from Sydney University (SU) soil was able to co-metabolically degrade TCE. The (SU) methanotrophic
10 citations
TL;DR: In this paper, the authors have isolated fourteen hydrocarbonoclastic bacterial strains from the crude oil contaminated soil of Assam, India, which were designated as RC1-RC14 that includes Alcaligenes, Bacillus, Enterobacter, and Pseudomonas species; which were able to metabolize crude oil to different extents.
10 citations
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TL;DR: The organisms were classified into five groups on the basis of morphology, fine structure, and type of resting stage formed (exospores and different types of cysts) and into subgroups on other properties.
Abstract: SUMMARY
More than 100 Gram-negative, strictly aerobic, methane-utilizing bacteria were isolated. All used only methane and methanol of the substrates tested for growth. The organisms were classified into five groups on the basis of morphology, fine structure, and type of resting stage formed (exospores and different types of cysts) and into subgroups on other properties. Methods of enrichment, isolation and culture are described.
1,343 citations
01 Jan 1985
TL;DR: It is confirmed that PCE can be transformed by reductive dehalogenation to TCE, dichloroethylene, and vinyl chloride (VC) under anaerobic conditions and suggested that potential exists for the complete mineralization of PCE to CO2 in soil and aquifer systems and in biological treatment processes.
Abstract: (TCE), common industrial solvents, areamong themost frequent contaminants foundingroundwater supplies. Duetothepotential toxicity andcarcinogenicity of chlorinated ethylenes, knowledge abouttheir transformation potential isimportant inevaluating their environmental fate. Theresults ofthis study confirm thatPCEcanbetransformed byreductive dehalogenation toTCE,dichloroethylene, andvinyl chloride (VC)underanaerobic conditions. Inaddition, [14C]PCE wasat least partially mineralized toCO2.Mineralization of24%ofthePCEoccurred inacontinuous-flow fixed-film methanogenic columnwitha liquid detention timeof4days. TCE was themajorintermediate formed, but traces ofdichloroethylene isomers andVC were alsofound. Inother columnstudies undera different setof methanogenic conditions, nearly quantitative conversion ofPCE toVC was found.Thesestudies clearly demonstrate thatTCEandVC aremajorintermediates inPCEbiotransformation underanaerobic conditions andsuggest thatpotential exists forthecomplete mineralization ofPCEtoCO2insoil andaquifer systems and inbiological treatment processes. Widespread contamination ofgroundwater byhalogenatedcompounds (12) hasledtoinvestigations todetermine their fateintheenvironment. Previous studies haveillustrated thata potential exists fortheir biotransformation underanaerobic conditions that areconducive tomethanogenesis. Fieldstudies withreclaimed wastewater injected into an aquifer indicated thattrihalomethanes were transformedwithhalf-lives of30daysandtetrachloroethylene (PCE),trichloroethylene
585 citations
TL;DR: In this paper, the results of a column study confirm that trichloroethylene (PCE) can be transformed by reductive dehalogenation to TCE, dichloromethane (DHE), and vinyl chloride (VC) under anaerobic conditions.
Abstract: Tetrachloroethylene (PCE) and trichloroethylene (TCE), common industrial solvents, are among the most frequent contaminants found in groundwater supplies. Due to the potential toxicity and carcinogenicity of chlorinated ethylenes, knowledge about their transformation potential is important in evaluating their environmental fate. The results of this study confirm that PCE can be transformed by reductive dehalogenation to TCE, dichloroethylene, and vinyl chloride (VC) under anaerobic conditions. In addition, [14C]PCE was at least partially mineralized to CO2. Mineralization of 24% of the PCE occurred in a continuous-flow fixed-film methanogenic column with a liquid detention time of 4 days. TCE was the major intermediate formed, but traces of dichloroethylene isomers and VC were also found. In other column studies under a different set of methanogenic conditions, nearly quantitative conversion of PCE to VC was found. These studies clearly demonstrate that TCE and VC are major intermediates in PCE biotransformation under anaerobic conditions and suggest that potential exists for the complete mineralization of PCE to CO2 in soil and aquifer systems and in biological treatment processes.
565 citations
TL;DR: Trichloroethylene was shown to degrade aerobically to carbon dioxide in an unsaturated soil column exposed to a mixture of natural gas in air (0.6%).
Abstract: Trichloroethylene was shown to degrade aerobically to carbon dioxide in an unsaturated soil column exposed to a mixture of natural gas in air (0.6%).
388 citations
TL;DR: In this paper, 29 composes organiques volatils, de 5 trihalomethanes, and du carbone organique total de 945 reseaux d'alimentation d'eau
Abstract: Resultats de mesure de 29 composes organiques volatils, de 5 trihalomethanes, et du carbone organique total de 945 reseaux d'alimentation d'eau
368 citations