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'''Cometabolism''' is defined as the simultaneous [[Chemical decomposition|degradation]] of two [[Chemical compound|compounds]], in which the degradation of the second compound (the secondary [[Substrate (chemistry)|substrate]]) depends on the presence of the first compound (the primary [[Substrate (chemistry)|substrate]]). <ref name=": |
'''Cometabolism''' is defined as the simultaneous [[Chemical decomposition|degradation]] of two [[Chemical compound|compounds]], in which the degradation of the second compound (the secondary [[Substrate (chemistry)|substrate]]) depends on the presence of the first compound (the primary [[Substrate (chemistry)|substrate]]). <ref name=":0">{{Cite journal|last1=Joshua|first1=C. J.|last2=Dahl|first2=R.|last3=Benke|first3=P. I.|last4=Keasling|first4=J. D.|year=2011|title=Absence of Diauxie during Simultaneous Utilization of Glucose and Xylose by Sulfolobus acidocaldarius|journal=J Bacteriol|volume=193|issue=6|pages=1293–1301|doi=10.1128/JB.01219-10|pmc=3067627|pmid=21239580}}</ref> This is in contrast to '''simultaneous catabolism''', where each substrate is [[Catabolism|catabolized]] concomitantly by different [[Enzyme|enzymes]].<ref name=":0" /><ref>{{Cite journal|last1=Gulvik|first1=C. A.|last2=Buchan|first2=A.|year=2013|title=Simultaneous catabolism of plant-derived aromatic compounds results in enhanced growth for members of the Roseobacter lineage|journal=Appl Environ Microbiol|volume=79|issue=12|pages=3716–3723|doi=10.1128/AEM.00405-13|pmc=3675927|pmid=23563956}}</ref> Cometabolism occurs when an enzyme produced by an organism to catalyze the degradation of it's growth-substrate to derive energy and carbon from it is also capable of degrading additional compounds. The fortituous degradation of these additional compounds does not support the growth of the bacteria, and some of these compounds can even be toxic in certain concentrations to the bacteria.<ref name=":1">{{Cite journal|last=Qin|first=Ke|last2=Struckhoff|first2=Garrett C.|last3=Agrawal|first3=Abinash|last4=Shelley|first4=Michael L.|last5=Dong|first5=Hailiang|date=2015-01-01|title=Natural attenuation potential of tricholoroethene in wetland plant roots: Role of native ammonium-oxidizing microorganisms|url=http://www.sciencedirect.com/science/article/pii/S0045653514011072|journal=Chemosphere|volume=119|issue=Supplement C|pages=971–977|doi=10.1016/j.chemosphere.2014.09.040}}</ref><ref name=":2">{{Cite journal|last=Nzila|first=Alexis|date=2013-07-01|title=Update on the cometabolism of organic pollutants by bacteria|url=http://www.sciencedirect.com/science/article/pii/S0269749113001759|journal=Environmental Pollution|volume=178|issue=Supplement C|pages=474–482|doi=10.1016/j.envpol.2013.03.042}}</ref> |
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The first report of this phenomena was the degredation of ethene by the species ''[[Pseudomonas methanica]].''<ref name=": |
The first report of this phenomena was the degredation of ethene by the species ''[[Pseudomonas methanica]].''<ref name=":2" /> These bacteria degrade their growth-substrate methane with the enzyme [[Methane monooxygenase|methane monooxygenase(MMO)]]. MMO was discovered to be capable of degrading [[Ethylene|ethene]] and propene, although the bacteria were unable to use these compounds as energy and carbon sources to grow. <ref name=":2" /> |
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Another example is ''[[Mycobacterium vaccae]]'', which uses an alkane monooxygenase enzyme to oxidize propane. Accidentally, this enzyme also oxidizes, at no additional cost for ''M. vaccae'', [[cyclohexane]] into [[cyclohexanol]]. Thus, cyclohexane is co-metabolized in the presence of propane. This allows for the commensal growth of ''[[Pseudomonas]]'' on cyclohexane. The latter can metabolize cyclohexanol, but not cyclohexane. <ref>{{Cite journal|last=Beam|first=H. W.|last2=Perry|first2=J. J.|date=1973-03-01|title=Co-metabolism as a factor in microbial degradation of cycloparaffinic hydrocarbons|url=https://link.springer.com/article/10.1007/BF00409542|journal=Archiv für Mikrobiologie|language=en|volume=91|issue=1|pages=87–90|doi=10.1007/BF00409542|issn=0003-9276}}</ref><ref name=": |
Another example is ''[[Mycobacterium vaccae]]'', which uses an alkane monooxygenase enzyme to oxidize propane. Accidentally, this enzyme also oxidizes, at no additional cost for ''M. vaccae'', [[cyclohexane]] into [[cyclohexanol]]. Thus, cyclohexane is co-metabolized in the presence of propane. This allows for the commensal growth of ''[[Pseudomonas]]'' on cyclohexane. The latter can metabolize cyclohexanol, but not cyclohexane. <ref>{{Cite journal|last=Beam|first=H. W.|last2=Perry|first2=J. J.|date=1973-03-01|title=Co-metabolism as a factor in microbial degradation of cycloparaffinic hydrocarbons|url=https://link.springer.com/article/10.1007/BF00409542|journal=Archiv für Mikrobiologie|language=en|volume=91|issue=1|pages=87–90|doi=10.1007/BF00409542|issn=0003-9276}}</ref><ref name=":3">{{Cite journal|last=Ryoo|first=D.|last2=Shim|first2=H.|last3=Canada|first3=K.|last4=Barbieri|first4=P.|last5=Wood|first5=T. K.|date=July 2000|title=Aerobic degradation of tetrachloroethylene by toluene-o-xylene monooxygenase of Pseudomonas stutzeri OX1|url=https://www.ncbi.nlm.nih.gov/pubmed/10888848|journal=Nature Biotechnology|volume=18|issue=7|pages=775–778|doi=10.1038/77344|issn=1087-0156|pmid=10888848}}</ref> |
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=='''Cometabolism in Bioremediation'''== |
=='''Cometabolism in Bioremediation'''== |
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Some of the molecules that are cometabolically degraded by bacteria are [[xenobiotic]], [[Persistent, bioaccumulative and toxic substances|persistent]] compounds, such as [[Tetrachloroethylene|PCE]], [[Tetrachloroethylene|TCE]], and [[MTBE]], that have harmful effects on several types of environments. Co-metabolism is thus used as an approach to [[Biodegradation|biologically degrade]] [[hazardous]] [[Solvent|solvents]]. <ref name=": |
Some of the molecules that are cometabolically degraded by bacteria are [[xenobiotic]], [[Persistent, bioaccumulative and toxic substances|persistent]] compounds, such as [[Tetrachloroethylene|PCE]], [[Tetrachloroethylene|TCE]], and [[MTBE]], that have harmful effects on several types of environments. Co-metabolism is thus used as an approach to [[Biodegradation|biologically degrade]] [[hazardous]] [[Solvent|solvents]]. <ref name=":4">{{Cite journal|last=Li|first=Shanshan|last2=Wang|first2=Shan|last3=Yan|first3=Wei|date=2016|title=Biodegradation of Methyl tert-Butyl Ether by Co-Metabolism with a Pseudomonas sp. Strain|url=http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5036716/|journal=International Journal of Environmental Research and Public Health|volume=13|issue=9|pages=|doi=10.3390/ijerph13090883|issn=1661-7827|pmc=PMC5036716|pmid=27608032|via=}}</ref><ref name=":2" /> |
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Cometabolism can be used for the [[biodegradation]] of [[Methyl tert-butyl ether|methyl-tert-butyl ether (MTBE)]]: an aquatic environment pollutant. Some ''[[Pseudomonas aeruginosa|Pseudomonas]]'' members were found to be able to fully degrade MTBE cometabolically with the enzymes they produce to [[Redox|oxidize]] [[Alkane|n-alkanes]] (e.g. [[methane]], [[propane]]). <ref name=": |
Cometabolism can be used for the [[biodegradation]] of [[Methyl tert-butyl ether|methyl-tert-butyl ether (MTBE)]]: an aquatic environment pollutant. Some ''[[Pseudomonas aeruginosa|Pseudomonas]]'' members were found to be able to fully degrade MTBE cometabolically with the enzymes they produce to [[Redox|oxidize]] [[Alkane|n-alkanes]] (e.g. [[methane]], [[propane]]). <ref name=":4" /> |
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Additionally, a promising method of [[bioremediation]] of chlorinated solvents involves cometabolism of the contaminants by [[aerobic microorganisms]] in groundwater and soils. Several aerobic microorganisms have been demonstrated to be capable of doing this, including [[Alkane|n-alkane]], [[Aromatic hydrocarbon|aromatic compound]] (e.g. [[toluene]], [[phenol]]) and [[ammonium]] oxidizers.<ref name=": |
Additionally, a promising method of [[bioremediation]] of chlorinated solvents involves cometabolism of the contaminants by [[aerobic microorganisms]] in groundwater and soils. Several aerobic microorganisms have been demonstrated to be capable of doing this, including [[Alkane|n-alkane]], [[Aromatic hydrocarbon|aromatic compound]] (e.g. [[toluene]], [[phenol]]) and [[ammonium]] oxidizers.<ref name=":2" /><ref name=":1" />One example is ''Pseudomonas stutzeri OX1'', which can degrade a hazardous, and water-soluble compound [[Tetrachloroethylene|tetrachloroethylene (PCE)]].<ref name=":3" /> PCE, one of the major underground water contaminants, was regarded as being undegradable under [[Aerobic condition|aerobic]] conditions and only degraded via [[reductive dehalogenation]] to be used as a growth-substrate by organisms.<ref name=":3" /> Reductive dehalogenation often results in the partial dechlorination of the PCE, giving rise to toxic compounds such as [[Trichloroethylene|TCE]], [[Dichloroethene|DCE]], and [[vinyl chloride]]. ''Pseudomonas st. OX1'' can degrade PCE under aerobic conditions by using toluene-o-xylene monooxygenase (ToMO), an enzyme they produce to derive energy and carbon from toluene and several other aromatic compounds. This biological process could be utilized to remove PCE from aerobic polluted sites.<ref name=":3" /> |
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However, the difficulties and high costs of maintaining the growth-substrates of the organisms capable of cometabolising these hazardous compounds and providing them an aerobic environment have led to the limited field-scale application of cometabolism for pollutant solvent degradation. Recently, this method of remediation has been proposed to be improved by the substitution of the synthetic [[Aromatic hydrocarbon|aromatic]] growth-substrates (e.g. toluene) of these bacteria with cheap, non-toxic plant secondary metabolites.<ref>{{Cite journal|last=Fraraccio|first=Serena|last2=Strejcek|first2=Michal|last3=Dolinova|first3=Iva|last4=Macek|first4=Tomas|last5=Uhlik|first5=Ondrej|date=2017-08-16|title=Secondary compound hypothesis revisited: Selected plant secondary metabolites promote bacterial degradation of cis-1,2-dichloroethylene (cDCE)|url=https://www.ncbi.nlm.nih.gov/pubmed/28814712|journal=Scientific Reports|volume=7|issue=1|pages=8406|doi=10.1038/s41598-017-07760-1|issn=2045-2322|pmc=PMC5559444|pmid=28814712}}</ref> |
However, the difficulties and high costs of maintaining the growth-substrates of the organisms capable of cometabolising these hazardous compounds and providing them an aerobic environment have led to the limited field-scale application of cometabolism for pollutant solvent degradation. Recently, this method of remediation has been proposed to be improved by the substitution of the synthetic [[Aromatic hydrocarbon|aromatic]] growth-substrates (e.g. toluene) of these bacteria with cheap, non-toxic plant secondary metabolites.<ref>{{Cite journal|last=Fraraccio|first=Serena|last2=Strejcek|first2=Michal|last3=Dolinova|first3=Iva|last4=Macek|first4=Tomas|last5=Uhlik|first5=Ondrej|date=2017-08-16|title=Secondary compound hypothesis revisited: Selected plant secondary metabolites promote bacterial degradation of cis-1,2-dichloroethylene (cDCE)|url=https://www.ncbi.nlm.nih.gov/pubmed/28814712|journal=Scientific Reports|volume=7|issue=1|pages=8406|doi=10.1038/s41598-017-07760-1|issn=2045-2322|pmc=PMC5559444|pmid=28814712}}</ref> |
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Revision as of 07:47, 20 November 2017
Cometabolism is defined as the simultaneous degradation of two compounds, in which the degradation of the second compound (the secondary substrate) depends on the presence of the first compound (the primary substrate). [1] This is in contrast to simultaneous catabolism, where each substrate is catabolized concomitantly by different enzymes.[1][2] Cometabolism occurs when an enzyme produced by an organism to catalyze the degradation of it's growth-substrate to derive energy and carbon from it is also capable of degrading additional compounds. The fortituous degradation of these additional compounds does not support the growth of the bacteria, and some of these compounds can even be toxic in certain concentrations to the bacteria.[3][4]
The first report of this phenomena was the degredation of ethene by the species Pseudomonas methanica.[4] These bacteria degrade their growth-substrate methane with the enzyme methane monooxygenase(MMO). MMO was discovered to be capable of degrading ethene and propene, although the bacteria were unable to use these compounds as energy and carbon sources to grow. [4]
Another example is Mycobacterium vaccae, which uses an alkane monooxygenase enzyme to oxidize propane. Accidentally, this enzyme also oxidizes, at no additional cost for M. vaccae, cyclohexane into cyclohexanol. Thus, cyclohexane is co-metabolized in the presence of propane. This allows for the commensal growth of Pseudomonas on cyclohexane. The latter can metabolize cyclohexanol, but not cyclohexane. [5][6]
Cometabolism in Bioremediation
Some of the molecules that are cometabolically degraded by bacteria are xenobiotic, persistent compounds, such as PCE, TCE, and MTBE, that have harmful effects on several types of environments. Co-metabolism is thus used as an approach to biologically degrade hazardous solvents. [7][4]
Cometabolism can be used for the biodegradation of methyl-tert-butyl ether (MTBE): an aquatic environment pollutant. Some Pseudomonas members were found to be able to fully degrade MTBE cometabolically with the enzymes they produce to oxidize n-alkanes (e.g. methane, propane). [7]
Additionally, a promising method of bioremediation of chlorinated solvents involves cometabolism of the contaminants by aerobic microorganisms in groundwater and soils. Several aerobic microorganisms have been demonstrated to be capable of doing this, including n-alkane, aromatic compound (e.g. toluene, phenol) and ammonium oxidizers.[4][3]One example is Pseudomonas stutzeri OX1, which can degrade a hazardous, and water-soluble compound tetrachloroethylene (PCE).[6] PCE, one of the major underground water contaminants, was regarded as being undegradable under aerobic conditions and only degraded via reductive dehalogenation to be used as a growth-substrate by organisms.[6] Reductive dehalogenation often results in the partial dechlorination of the PCE, giving rise to toxic compounds such as TCE, DCE, and vinyl chloride. Pseudomonas st. OX1 can degrade PCE under aerobic conditions by using toluene-o-xylene monooxygenase (ToMO), an enzyme they produce to derive energy and carbon from toluene and several other aromatic compounds. This biological process could be utilized to remove PCE from aerobic polluted sites.[6]
However, the difficulties and high costs of maintaining the growth-substrates of the organisms capable of cometabolising these hazardous compounds and providing them an aerobic environment have led to the limited field-scale application of cometabolism for pollutant solvent degradation. Recently, this method of remediation has been proposed to be improved by the substitution of the synthetic aromatic growth-substrates (e.g. toluene) of these bacteria with cheap, non-toxic plant secondary metabolites.[8]
References
- ^ a b Joshua, C. J.; Dahl, R.; Benke, P. I.; Keasling, J. D. (2011). "Absence of Diauxie during Simultaneous Utilization of Glucose and Xylose by Sulfolobus acidocaldarius". J Bacteriol. 193 (6): 1293–1301. doi:10.1128/JB.01219-10. PMC 3067627. PMID 21239580.
- ^ Gulvik, C. A.; Buchan, A. (2013). "Simultaneous catabolism of plant-derived aromatic compounds results in enhanced growth for members of the Roseobacter lineage". Appl Environ Microbiol. 79 (12): 3716–3723. doi:10.1128/AEM.00405-13. PMC 3675927. PMID 23563956.
- ^ a b Qin, Ke; Struckhoff, Garrett C.; Agrawal, Abinash; Shelley, Michael L.; Dong, Hailiang (2015-01-01). "Natural attenuation potential of tricholoroethene in wetland plant roots: Role of native ammonium-oxidizing microorganisms". Chemosphere. 119 (Supplement C): 971–977. doi:10.1016/j.chemosphere.2014.09.040.
- ^ a b c d e Nzila, Alexis (2013-07-01). "Update on the cometabolism of organic pollutants by bacteria". Environmental Pollution. 178 (Supplement C): 474–482. doi:10.1016/j.envpol.2013.03.042.
- ^ Beam, H. W.; Perry, J. J. (1973-03-01). "Co-metabolism as a factor in microbial degradation of cycloparaffinic hydrocarbons". Archiv für Mikrobiologie. 91 (1): 87–90. doi:10.1007/BF00409542. ISSN 0003-9276.
- ^ a b c d Ryoo, D.; Shim, H.; Canada, K.; Barbieri, P.; Wood, T. K. (July 2000). "Aerobic degradation of tetrachloroethylene by toluene-o-xylene monooxygenase of Pseudomonas stutzeri OX1". Nature Biotechnology. 18 (7): 775–778. doi:10.1038/77344. ISSN 1087-0156. PMID 10888848.
- ^ a b Li, Shanshan; Wang, Shan; Yan, Wei (2016). "Biodegradation of Methyl tert-Butyl Ether by Co-Metabolism with a Pseudomonas sp. Strain". International Journal of Environmental Research and Public Health. 13 (9). doi:10.3390/ijerph13090883. ISSN 1661-7827. PMC 5036716. PMID 27608032.
{{cite journal}}: CS1 maint: PMC format (link) CS1 maint: unflagged free DOI (link) - ^ Fraraccio, Serena; Strejcek, Michal; Dolinova, Iva; Macek, Tomas; Uhlik, Ondrej (2017-08-16). "Secondary compound hypothesis revisited: Selected plant secondary metabolites promote bacterial degradation of cis-1,2-dichloroethylene (cDCE)". Scientific Reports. 7 (1): 8406. doi:10.1038/s41598-017-07760-1. ISSN 2045-2322. PMC 5559444. PMID 28814712.
{{cite journal}}: CS1 maint: PMC format (link)