Pseudomonas putida’s Role In The Bioremediation Of Plastic: Difference between revisions

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=''Pseudomonas putida''=
=''Pseudomonas putida''=
[[File:P.putida.jpg|300px|thumb|left| FIG1. Pseudomonas putida F1 strain observed using microscopy]]


Domain: Bacteria
Domain: Bacteria
Line 20: Line 22:
Species: ''Pseudomonas putida''
Species: ''Pseudomonas putida''


''Pseudomonas putida'' is a gram-negative, rod-shaped bacteria which undergoes aerobic metabolism. It is normally found in terrestrial and aquatic environments where oxygen is abundant. ''P. putida'' is well known for being one of the most metabolically diverse organisms capable of breaking down both natural organic molecules such as vanillin, limonene and camphor [[#References|[5]]] as well as industrial compounds such as toluene and styrene [[#References|[4]]]. There is great interest in the genomic analysis of ''P. putida'' by a joint genome sequencing project by several institutes from the U.S and Germany with one of the most well studied strains being the ''P. putida'' K2440 strain. The genome of this particular strain contains 6181 kbp with 5420 ORFs. Out of all these ORFs, 3571 ORFs were assigned putative roles through comparisons against a non-redundant protein database [[#References|[6]]]. Although these ORFs may not all be translated, the abundance of ORFs suggest that the bacteria is capable of various metabolic activities. In addition, to achieve the metabolic versatility of the bacteria requires the ability to cope with numerous abiotic stresses [[#References|[7]]]. This is further supported by the genomic analysis of KT2440 where an unusually ample amount of transporters, oxidoreductases, mono-oxygenases, dioxygenases, ferredoxins, sulphur metabolism proteins, dehydrogenases, and cytochromes are found to be encoded in the genome (6). Aside from P. putida, several other bacteria are also being looked into for bioremediation purposes.
''Pseudomonas putida'' is a gram-negative, rod-shaped bacteria which undergoes aerobic metabolism. It is normally found in terrestrial and aquatic environments where oxygen is abundant. ''P.putida'' is well known for being one of the most metabolically diverse organisms capable of breaking down both natural organic molecules such as vanillin, limonene and camphor [[#References|[5]]] as well as industrial compounds such as toluene and styrene [[#References|[4]]]. There is great interest in the genomic analysis of ''P.putida'' by a joint genome sequencing project by several institutes from the U.S and Germany with one of the most well studied strains being the ''P.putida'' K2440 strain. The genome of this particular strain contains 6181 kbp with 5420 ORFs. Out of all these ORFs, 3571 ORFs were assigned putative roles through comparisons against a non-redundant protein database [[#References|[6]]]. Although these ORFs may not all be translated, the abundance of ORFs suggest that the bacteria is capable of various metabolic activities. In addition, to achieve the metabolic versatility of the bacteria requires the ability to cope with numerous abiotic stresses [[#References|[7]]]. This is further supported by the genomic analysis of KT2440 where an unusually ample amount of transporters, [http://en.wikipedia.org/wiki/Oxidoreductase oxidoreductases], mono-oxygenases, dioxygenases, [http://en.wikipedia.org/wiki/Ferredoxin ferredoxins], sulphur metabolism proteins, dehydrogenases, and [http://en.wikipedia.org/wiki/Cytochrome cytochromes] are found to be encoded in the genome [[#References|[6]]]. Aside from ''P. putida'', several other bacteria are also being looked into for bioremediation purposes.


=Morphology=
=Properties of Polystyrene=


The members of the ''Ignicoccus''  genus are motile irregular coccoid cells that range in diameter from 1 to 3 µm. The motility observed is due to the presence of flagella, but unfortunately the polarity of the flagella is not yet fully elucidated. They are known to have an outer-membrane but no [http://en.wikipedia.org/wiki/S-layer S-layer]. This is a novel characteristic for these [http://en.wikipedia.org/wiki/Archaea Archaea] because''Ignicoccus'' are the only known Archaea that have been shown to possess an outer-membrane[[#References|[2]]] [[#References|[10]]] .
[[File:Styrene.jpg|400px|thumb|right| FIG2. Styrene spontaneously polymerizes to polystyrene at room temperature]][[#References|[9]]]


[[File:Huber-abb2.jpg|300px|thumb|left| Ultrathin section of an ''Ignicoccus hospitalis'' cell.]]
Huge amounts of potentially toxic styrene are produced each year, making the removal of the pollutant from the environment of critical importance. There are few microbes capable of metabolizing styrene as a sole source of carbon; these bacteria are able to transform the recalcitrant and persistent styrene into another molecule that’s easier to break down such as [http://en.wikipedia.org/wiki/Polyhydroxyalkanoates polyhydroxyalkanoate] or PHA [[#References|[10]]]. Styrene is the simplest alkenyl benzene. It is colourless, oil-like and not very soluble in water. The polymerization of styrene into polystyrene is a spontaneous process that can occur at room temperature [[#References|[9]]]. Though less toxic than benzene or polycyclic aromatic hydrocarbons, styrene is still potentially carcinogenic. It also affects the central nervous system if inhaled. Chronic exposure to styrene could result in memory loss, difficulties in concentration and learning, and cancer [[#References|[11]]]. Most industries deal with styrene pollutants through combustion or land injection. Both methods are flawed as soil styrene rapidly degrades at first but starts to persist subsequently [[#References|[13]]]. It is also observed that aerosol styrene created from combustion is capable of damaging the ozone by reacting with O3 to form highly unstable and reactive ozonide [[#References|[3]]][[#References|[9]]].




==Outer-Membrane==


The outer-membrane of ''Ignicoccus''  species was found to be composed of various derivatives of the typical lipid [http://en.wikipedia.org/wiki/Archaeol archaeol], including the derivative known as [http://en.wikipedia.org/wiki/Caldarchaeol caldarchaeol] [[#References|[5]]] . The outer-membrane is dominated by a pore composed of the Imp1227 protein (''Ignicoccus''  outer membrane protein 1227). The Imp1227 protein forms a large nonamer ring with a predicted pore size of 2nm[[#References|[7]]] .
=Bioremediation of Styrene=


=Metabolism=
It is suggested that ''P.putida'' has relatively relaxed substrate specificity; this is further supported by a study showing that when a strain of ''P.putida'' is isolated from conditions where [http://en.wikipedia.org/wiki/Cumene isopropylbenzene] is normally the only carbon source, it is able to grow using alternate aromatic source [[#References|[14]]].


''Ignicoccus'' species are [http://en.wikipedia.org/wiki/Chemolithoautotroph chemolithoautotrophs] that use molecular hydrogen as the inorganic electron donor and elemental sulphur as the inorganic terminal electron acceptor[[#References|[1]]] . The reduction of the elemental sulphur results in the production of hydrogen sulphide gas.  
''P.putida'' is also found to be capable of biodegrading styrene in two different pathways via two modes of initial attack of styrene from the isolation of [[#References|[15]]]. The isolation of two different oxidation products, 2-phenyl-2-propen-1-nol and 1,2-dihydroxy-3-isopropenyl-3-cyclohexene  suggest different initial steps of styrene metabolism by ''P.putida'' [[#References|[14]]]. The first being oxidation of the vinyl side chain as the predominant pathway under aerobic conditions; the second involves the direct oxidation of the aromatic ring [[#References|[9]]][[#References|[12]]][[#References|[14]]][[#References|[15]]][[#References|[16]]].


''Ignicoccus'' are autotrophs in that they fix their own carbon dioxide into organic molecules. The carbon dioxide fixation process they use is a novel process called [http://www.pnas.org/content/105/22/7851.full a dicarboxylate/4-hydroxybutyrate autotrophic carbon assimilation cycle] that involves 14 different enzymes[[#References|[8]]] .
[[File:Map.jpg|700px|thumb|left| FIG3. Simplified styrene metabolistic pathways for side chain and aromatic ring initial attacks]]


Members of the ''Ignicoccus''  genus are able to use ammonium as a nitrogen source.
==Side Chain Pathway==


==Growth Conditions==
The side chain oxidation forms several intermediates that all convert to [http://en.wikipedia.org/wiki/Phenylacetic_acid phenylacetic acid] (PAA), this step is also called the “upper pathway” of the styrene metabolism [[#References|[9]]][[#References|[12]]]. The step after the production of phenylacetic acid is named the “lower pathway” of the styrene metabolism, which involves the production of phenylacetyl-CoA [[#References|[7]]].


Because members of the ''Ignicoccus''  genus are [http://en.wikipedia.org/wiki/Hyperthermophile hyperthermophiles] and obligate anaerobes, it is not surprising that their growth conditions are very complex. They are grown in a liquid medium known as ½ SME ''Ignicoccus''  which is a solution of synthetic sea water which is then made anaerobic.
The first step of the upper pathway involves the conversion of styrene to styrene oxide, this is done by a monooxygenase. Styrene oxide is then isomerised into phenylacetaldehyde. Finally, phenylacetaldehyde would be oxidized to become phenylacetic acid [[#References|[9]]][[#References|[12]]]. In the lower pathway, phenylacetic acid will be joined to CoA to make phenylacetyl-CoA by a ligase. This molecule is then able to be cleaved into acetyl CoA which can enter the TCA cycle [[#References|[9]]]. The degradation of the pathway is not linear and more branches exist based on the availability of nutrient [[#References|[10]]].


Grown in this media at their optimal growth temperature of 90C, the members of the ''Ignicoccus''  genus typically reach a cell density of ~4x107cells/mL[[#References|[1]]] .
==Aromatic Ring Pathway==


The addition of [http://en.wikipedia.org/wiki/Yeast_extract yeast extract] to the ½ SME media has been shown to stimulate the growth and increase maximum cell density achieved. The mechanism by which this is achieved is not known[[#References|[1]]] .
The direct attack on the aromatic ring results in styrene cis-glycol followed by 3-vinylcatechol formation [[#References|[9]]][[#References|[17]]]. Then 3-vinylcatechol will be cleaved by several enzymes such as catechol 2,3-dioxygenase, semialdehyde hydrolase, hydratase and aldolase to become a muconic semialdehyde [[#References|[17]]]. The muconic semialdehyde will then be metabolized to [http://en.wikipedia.org/wiki/Pyruvic_acid pyruvate] and [http://en.wikipedia.org/wiki/Acetaldehyde acetaldehyde] to be used in further metabolic pathways [[#References|[9]]].
=References=


(1) Welp, E., Kogevinas, M., Andersen, A., Bellander, T., et al. “Exposure to Styrene and Mortality from Nervous System Diseases and Mental Disorders.” Am. J. Epidemiol. 1996, 144(7), 623-633.


=Symbiosis=
(2) Przybulewska, K., Wieczorek, A. and Nowak, A. “Isolation of Microorganisms Capable of Styrene Degradation.” Polish J. of Environ. 2006, 15(5), 777-783.


''Ignicoccus hospitalis''  is the only member of the genus ''Ignicoccus'' that has been shown to have an extensive [http://en.wikipedia.org/wiki/Symbiosis symbiotic relationship] with another organism.
(3) Hisatsune, I.C., Shinoda, K., Heicklen, J. 1978. “Low-temperature infrared studies of the styrene-ozone reaction, formation of an unusual ozonide.” J. Am. Chem. Soc. 1978, 101(10), 2524-2526.


''Ignicoccus hospitalis''  has been shown to engage in symbiosis with ''Nanoarchaeum equitans'' . ''Nanoarchaeum equitans''  is a very small coccoid species with a cell diameter of 0.4 µm[[#References|[9]]] . Genome analysis has provided much of the known information about this species.
(4) Marques, S., Ramos, J.L., “Transcriptional control of the Pseudomonas putida TOL plasmid catabolic pathways.” J. Mol. Microbiol. 1993, 9(5), 923-929.


To further complicate the symbiotic relationship between both species, it’s been observed that the presence of ''Nanoarchaeum equitans''  on the surface of ''Ignicoccus hospitalis''  somehow inhibits the cell replication of ''Ignicoccus hospitalis'' . How or why this occurs has not yet been elucidated[[#References|[3]]] .  
(5) Wackett, L.P. “Pseudomonas putida – a versatile biocatalyst.” Nat. Biotech. 2003, 21(2), 136-138.


[[File:Urzwerg.jpg|300px|thumb|right| ''Ignicoccus hospitalis'' with two attached  ''Nanoarchaeum equitans'' cells.]]
(6) Nelson, K., Weinel, C., Fraser, C., et al. “Complete genome sequence and comparative analysis of the metabolically versatile Pseudomonas putida KT2440.” Appl. Environ. Microbiol. 2002, 4(12), 799-808.


[[File:IhNeRelationship2 jpeg.jpg|250px|thumb|left| Epifluoroscence micrographs of an ''Ignicoccus hospitalis''and ''Nanoarchaeum equitans'' coculture stained with BacLight at various time points. Living cells stain green while dead cells stain red. (A) Exponential growth phase 3.25 hours after inoculation. (B) Transition into the stationary phase 7.5 hours after inoculation. (C) Stationary phase 10 hours after inoculation. (D) Stationary phase 23 hours after inoculation.]]
(7) Reva, O.N., Weinel, C., Weinel, M., et al. “Functional genomics of stress response in Pseudomonas putida KT2440.” J. Bacteriol. 2006, 188(11), 4079-4092.
 
 
==''Nanoarchaeum equitans''==
 
''Nanoarchaeum equitans'' has the smallest non-viral genome ever sequenced at 491kb[[#References|[9]]] . Analysis of the genome sequence indicates that 95% of the predicted proteins and stable RNA molecules are somehow involved in repair and replication of the cell and its genome[[#References|[3]]] .
 
Analysis of the genome also showed that ''Nanoarchaeum equitans''  lacks nearly all genes known to be required in amino acid, nucleotide, cofactor and lipid metabolism. This is partially supported by the evidence that ''Nanoarchaeum equitans''  has been shown to derive its cell membrane from its host ''Ignicoccus hospitalis''  cell membrane. The direct contact observed between ''Nanoarchaeum equitans'' and ''Ignicoccus hospitalis''  is hypothesized to form a pore between the two organisms in order to exchange metabolites or substrates (likely from ''Ignicoccus hospitalis''  towards ''Nanoarchaeum equitans'' due to the parasitic relationship). The exchange of periplasmic vesicles is not thought to be involved in metabolite or substrate exchange despite the presence of vesicles in the periplasm of ''Ignicoccus hospitalis'' .
 
These analyses of the ''Nanoarchaeum equitans'' genome support the fact of the extensive symbiotic relationship between ''Nanoarchaeum equitans'' and ''Ignicoccus hospitalis''. However, it has not yet been proven that it is a strictly parasitic relationship and further research may prove that there is a commensal relationship between the two species.  
 
=References=


(1) Burggraf S., Huber H., Mayer T., Rachel R., Stetter K.O. and Wyschkony I. ” Ignicoccus gen. nov., a novel genus of hyperthermophilic, chemolithoautotrophic Archaea, represented by two new species, Ignicoccus islandicus sp. nov. and Ignicoccus pacificus sp. nov.” International Journal of Systematic and Evolutionary Microbiology, 2000, Volume 50.
(8) Puchalka, J., Oberhardt, M.A., Godinho, M., et al. “Genome-scale reconstruction and analysis of the Pseudomonas putida KT2440 metabolic network facilitates applications in biotechnology.” PLoS. Comput. Biol. 2008, 4(10), 1-18.


(2) Naether D.J. and Rachel R. “The outer membrane of the hyperthermophilic archaeon Ignicoccus: dynamics, ultrastructure and composition.” Biochemical Society Transactions, 2004, Volume 32, part 2.
(9) Mooney, A., Ward, P.G., O’Connor, K.E. “Microbial degradation of styrene: biochemistry, molecular genetics, and perspectives for biotechnological applications.” Appl. Microbiol. Biotechnol. 2006, 71(1), 1-10.


(3) Giannone R.J., Heimerl T., Hettich R.L., Huber H., Karpinets T., Keller M., Kueper U., Podar M. and Rachel R. “Proteomic Characterization of Cellular and Molecular Processes that Enable the Nanoarchaeum equitans- Ignicoccus hospitalis Relationship.” PLoS ONE, 2011, Volume 6, Issue 8.
(10) Ward, P.G., de Roo, G., O’Connor, K.E. “Accumulation of polyhydroxyalkanoate from styrene and phenylacetic acid by Pseudomonas putida CA-3.” Appl. Environ. Microbiol. 2005, 71(4), 2046-2052.


(4) Eisenreich W., Gallenberger M., Huber H., Jahn U., Junglas B., Paper W., Rachel R. and Stetter K.O. “Nanoarchaeum equitans and Ignicoccus hospitalis: New Insights into a Unique, Intimate Association of Two Archaea.” Journal of Bacteriology, 2008, DOI: 10.1128/JB.01731-07.
(11) Gibbs, B.F., Mulligan, C.N. “Styrene toxicity: an ecotoxicological assessment.” Exotox. Environ. Safe. 1997, 38(3), 181-194.


(5) Grosjean E., Huber H., Jahn U., Sturt H, and Summons R. “Composition of the lipids of Nanoarchaeum equitans and their origin from its host Ignicoccus sp. strain KIN4/I.” Arch Microbiol, 2004, DOI: 10.1007/s00203-004-0725-x.
(12) O’Connor, K., Duetz, W., Wind, B., et al. “The effect of nutrient limitation of styrene metabolism in Pseudomonas putida CA-3.” Appl. Environ. Microbiol. 1996, 62(10), 3594-3599.


(6) Briegel A., Burghardt T., Huber H., Junglas B., Rachel R., Walther P. and Wirth R. “Ignicoccus hospitalis and Nanoarchaeum equitans: ultrastructure, cell–cell interaction, and 3D reconstruction from serial sections of freeze-substituted cells and by electron cryotomography.” Arch Microbiol, 2008, DOI 10.1007/s00203-008-0402-6.
(13) Fu, M.H. and Alexander, M. “Biodegradation of styrene in waterlogged soils and aquifer solids.” Soil Science. 1996, 161(12), 846-851.


(7) Burghardt T., Huber H., Junglas B., Naether D.J. and Rachel R. “The dominating outer membrane protein of the hyperthermophilic Archaeum Ignicoccus hospitalis: a novel pore-forming complex.” Molecular Microbiology, 2007, Volume 63.
(14) Bestetti, G., Galli, E., Benigni, C., et al. “Biotransformation of styrenes by a Pseudomonas putida.” Appl. Microbiol. Biotechnol. 1989, 30(3), 252-256.


(8) Berg I.A., Eisenreich W., Eylert E., Fuchs G., Gallenberger M., Huber H.,Jahn U. and Kockelkorn D. “A dicarboxylate/4-hydroxybutyrate autotrophic carbon assimilation cycle in the hyperthermophilic Archaeum Ignicoccus hospitalis.” PNAS, 2008, Volume 105, issue 22.
(15) Omori, T., Jigami, Y., Minoda, Y. “Microbial oxidation of a-methylstyrene and B-methylstyrene.” Agr. Biol. Chem. 1974, 38, 409-415.


(9) Brochier C., Gribaldo S., Zivanovic Y., Confalonieri F. and Forterre P. “Nanoarchaea: representatives of a novel archaeal phylum or a fast-evolving euryarchaeal lineage related to Thermococcales?Genome Biology 2005, DOI:10.1186/gb-2005-6-5-r42.
(16) Jigami, Y., Kawasaki, Y., Omori, T., et al. “Coexistence of different pathways in the metabolism of N-propyl-benzene by Pseudomonas sp.Appl. Environ. Microbiol. 1979, 38(5), 783-788.


(10) Huber H., Rachel R., Riehl S. and Wyschkony I. “The ultrastructure of Ignicoccus: Evidence for a novel outer membrane and for intracellular vesicle budding in an archaeon.” Archaea, 2002, Volume 1.
(17) Warhurst, A. M., Clarke, K. F., Hill, R. A., et al. “Metabolism of styrene by Rhodococcus rhodochrous.” Appl. Environ. Microbiol. 1994, 60(4), 1137-1145.

Latest revision as of 02:54, 30 November 2013

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Overview

With the rapid industrial development in recent decades, hazardous substance emission is causing more concern. One of the most common materials used in synthetic plastic and rubber is polystyrene, commonly known as styrofoam. This rigid polymer is made of an aromatic monomer phenylethene or styrene. Polystyrene is found to be very recalcitrant and persistent in the environment and the inhalation of polystyrene in the air could cause problems in the central nervous system [1]. The production of polystyrene is also found to be able to cause air pollution by altering the composition of the stratosphere and the troposphere depending on the process used [2]. Therefore it is of great interest to study microorganisms capable of the degradation of styrene such as Pseudomonas putida.

Pseudomonas putida

FIG1. Pseudomonas putida F1 strain observed using microscopy

Domain: Bacteria

Phylum: Proteobacteria

Class: Gamma proteobacteria

Order: Pseudomonadales

Family: Pseudomonadaceae

Genus: Pseudomonas

Species: Pseudomonas putida

Pseudomonas putida is a gram-negative, rod-shaped bacteria which undergoes aerobic metabolism. It is normally found in terrestrial and aquatic environments where oxygen is abundant. P.putida is well known for being one of the most metabolically diverse organisms capable of breaking down both natural organic molecules such as vanillin, limonene and camphor [5] as well as industrial compounds such as toluene and styrene [4]. There is great interest in the genomic analysis of P.putida by a joint genome sequencing project by several institutes from the U.S and Germany with one of the most well studied strains being the P.putida K2440 strain. The genome of this particular strain contains 6181 kbp with 5420 ORFs. Out of all these ORFs, 3571 ORFs were assigned putative roles through comparisons against a non-redundant protein database [6]. Although these ORFs may not all be translated, the abundance of ORFs suggest that the bacteria is capable of various metabolic activities. In addition, to achieve the metabolic versatility of the bacteria requires the ability to cope with numerous abiotic stresses [7]. This is further supported by the genomic analysis of KT2440 where an unusually ample amount of transporters, oxidoreductases, mono-oxygenases, dioxygenases, ferredoxins, sulphur metabolism proteins, dehydrogenases, and cytochromes are found to be encoded in the genome [6]. Aside from P. putida, several other bacteria are also being looked into for bioremediation purposes.

Properties of Polystyrene

FIG2. Styrene spontaneously polymerizes to polystyrene at room temperature

[9]

Huge amounts of potentially toxic styrene are produced each year, making the removal of the pollutant from the environment of critical importance. There are few microbes capable of metabolizing styrene as a sole source of carbon; these bacteria are able to transform the recalcitrant and persistent styrene into another molecule that’s easier to break down such as polyhydroxyalkanoate or PHA [10]. Styrene is the simplest alkenyl benzene. It is colourless, oil-like and not very soluble in water. The polymerization of styrene into polystyrene is a spontaneous process that can occur at room temperature [9]. Though less toxic than benzene or polycyclic aromatic hydrocarbons, styrene is still potentially carcinogenic. It also affects the central nervous system if inhaled. Chronic exposure to styrene could result in memory loss, difficulties in concentration and learning, and cancer [11]. Most industries deal with styrene pollutants through combustion or land injection. Both methods are flawed as soil styrene rapidly degrades at first but starts to persist subsequently [13]. It is also observed that aerosol styrene created from combustion is capable of damaging the ozone by reacting with O3 to form highly unstable and reactive ozonide [3][9].


Bioremediation of Styrene

It is suggested that P.putida has relatively relaxed substrate specificity; this is further supported by a study showing that when a strain of P.putida is isolated from conditions where isopropylbenzene is normally the only carbon source, it is able to grow using alternate aromatic source [14].

P.putida is also found to be capable of biodegrading styrene in two different pathways via two modes of initial attack of styrene from the isolation of [15]. The isolation of two different oxidation products, 2-phenyl-2-propen-1-nol and 1,2-dihydroxy-3-isopropenyl-3-cyclohexene suggest different initial steps of styrene metabolism by P.putida [14]. The first being oxidation of the vinyl side chain as the predominant pathway under aerobic conditions; the second involves the direct oxidation of the aromatic ring [9][12][14][15][16].

FIG3. Simplified styrene metabolistic pathways for side chain and aromatic ring initial attacks

Side Chain Pathway

The side chain oxidation forms several intermediates that all convert to phenylacetic acid (PAA), this step is also called the “upper pathway” of the styrene metabolism [9][12]. The step after the production of phenylacetic acid is named the “lower pathway” of the styrene metabolism, which involves the production of phenylacetyl-CoA [7].

The first step of the upper pathway involves the conversion of styrene to styrene oxide, this is done by a monooxygenase. Styrene oxide is then isomerised into phenylacetaldehyde. Finally, phenylacetaldehyde would be oxidized to become phenylacetic acid [9][12]. In the lower pathway, phenylacetic acid will be joined to CoA to make phenylacetyl-CoA by a ligase. This molecule is then able to be cleaved into acetyl CoA which can enter the TCA cycle [9]. The degradation of the pathway is not linear and more branches exist based on the availability of nutrient [10].

Aromatic Ring Pathway

The direct attack on the aromatic ring results in styrene cis-glycol followed by 3-vinylcatechol formation [9][17]. Then 3-vinylcatechol will be cleaved by several enzymes such as catechol 2,3-dioxygenase, semialdehyde hydrolase, hydratase and aldolase to become a muconic semialdehyde [17]. The muconic semialdehyde will then be metabolized to pyruvate and acetaldehyde to be used in further metabolic pathways [9].


References

(1) Welp, E., Kogevinas, M., Andersen, A., Bellander, T., et al. “Exposure to Styrene and Mortality from Nervous System Diseases and Mental Disorders.” Am. J. Epidemiol. 1996, 144(7), 623-633.

(2) Przybulewska, K., Wieczorek, A. and Nowak, A. “Isolation of Microorganisms Capable of Styrene Degradation.” Polish J. of Environ. 2006, 15(5), 777-783.

(3) Hisatsune, I.C., Shinoda, K., Heicklen, J. 1978. “Low-temperature infrared studies of the styrene-ozone reaction, formation of an unusual ozonide.” J. Am. Chem. Soc. 1978, 101(10), 2524-2526.

(4) Marques, S., Ramos, J.L., “Transcriptional control of the Pseudomonas putida TOL plasmid catabolic pathways.” J. Mol. Microbiol. 1993, 9(5), 923-929.

(5) Wackett, L.P. “Pseudomonas putida – a versatile biocatalyst.” Nat. Biotech. 2003, 21(2), 136-138.

(6) Nelson, K., Weinel, C., Fraser, C., et al. “Complete genome sequence and comparative analysis of the metabolically versatile Pseudomonas putida KT2440.” Appl. Environ. Microbiol. 2002, 4(12), 799-808.

(7) Reva, O.N., Weinel, C., Weinel, M., et al. “Functional genomics of stress response in Pseudomonas putida KT2440.” J. Bacteriol. 2006, 188(11), 4079-4092.

(8) Puchalka, J., Oberhardt, M.A., Godinho, M., et al. “Genome-scale reconstruction and analysis of the Pseudomonas putida KT2440 metabolic network facilitates applications in biotechnology.” PLoS. Comput. Biol. 2008, 4(10), 1-18.

(9) Mooney, A., Ward, P.G., O’Connor, K.E. “Microbial degradation of styrene: biochemistry, molecular genetics, and perspectives for biotechnological applications.” Appl. Microbiol. Biotechnol. 2006, 71(1), 1-10.

(10) Ward, P.G., de Roo, G., O’Connor, K.E. “Accumulation of polyhydroxyalkanoate from styrene and phenylacetic acid by Pseudomonas putida CA-3.” Appl. Environ. Microbiol. 2005, 71(4), 2046-2052.

(11) Gibbs, B.F., Mulligan, C.N. “Styrene toxicity: an ecotoxicological assessment.” Exotox. Environ. Safe. 1997, 38(3), 181-194.

(12) O’Connor, K., Duetz, W., Wind, B., et al. “The effect of nutrient limitation of styrene metabolism in Pseudomonas putida CA-3.” Appl. Environ. Microbiol. 1996, 62(10), 3594-3599.

(13) Fu, M.H. and Alexander, M. “Biodegradation of styrene in waterlogged soils and aquifer solids.” Soil Science. 1996, 161(12), 846-851.

(14) Bestetti, G., Galli, E., Benigni, C., et al. “Biotransformation of styrenes by a Pseudomonas putida.” Appl. Microbiol. Biotechnol. 1989, 30(3), 252-256.

(15) Omori, T., Jigami, Y., Minoda, Y. “Microbial oxidation of a-methylstyrene and B-methylstyrene.” Agr. Biol. Chem. 1974, 38, 409-415.

(16) Jigami, Y., Kawasaki, Y., Omori, T., et al. “Coexistence of different pathways in the metabolism of N-propyl-benzene by Pseudomonas sp.” Appl. Environ. Microbiol. 1979, 38(5), 783-788.

(17) Warhurst, A. M., Clarke, K. F., Hill, R. A., et al. “Metabolism of styrene by Rhodococcus rhodochrous.” Appl. Environ. Microbiol. 1994, 60(4), 1137-1145.