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Team:Bielefeld-Germany/Project/Background
From 2012.igem.org
Chemical waste in water?!
Water is the source of all life and covers 71% of the Earth’s surface. Healthy drinking water is an important aspect and essential for mankind. However, the growing industrialization, the production of chemical agents and the increasing consumption of pharmaceuticals is among the causes of the ever increasing pressure on the aquatic environment and on the availability and quality of safe and clean water. The continuous release of pharmaceuticals into the environment and the proven effects on biological systems. The measured environmental concentrations cause that water pollution is one of the main environmental worries of our society. According to a survey of March 2012 of the Public Opinion Analysis sector of the [http://www.europarl.europa.eu/meetdocs/2009_2014/documents/envi/pr/909/909091/909091en.pdf European Commission],
- 68 % of Europeans think that water quantity and quality problems are serious.
- 80 % believe that chemical pollution is a threat to the water environment.
- 62 % feel that they are not sufficiently informed about problems facing groundwater, lakes, rivers and coastal waters in their countries.
The birth control pill is a widespread contraception method. However, large amounts of these modified estrogens leave the body again in urine. According to the Federal Environment Agency in Germany (Umwelt Bundes Amt-UBA) several hundred tons of analgetics, antibiotics, beta blockers, X-ray contrast agents, anti-epileptic drugs, poly aromatic hydrocarbons pesticides ‘’etc.’’ get into the waste water through various ways, too, and in the end finds its way into rivers, lakes and in the drinking water.
The most substances which can be detected in the surface water possess one or more aromatic ring structure. Due to the aromatic structures the sewage treatment plants are not able to effectively degrade these substances with conventional methods. This means that a high proportion of these substances is being released into the environment. According to the IWW Rhine Westphalian Institute of Water Research gGmbH (IWW) environmental concentrations of [http://www.umweltbundesamt.de/chemikalien/veranstaltungen/ws-monitoring-arzneimittel/11_vortrag-abstract_bergmann.pdf 247] human and veterinary drugs can be measured in the environmental sewage effluent, the surface water, the groundwater, the drinking water and the sewage sludge. These substances include:
Sweeteners: Acesulfam, Sucralose
Antibiotics: Clarithromycin, Sulfamethoxazol, N4-Acetylsulfamethoxazol , Carbamazepin
Analgetics: Diclofenac , Ibuprofen
Benzotriazole: Benzotriazol, 4-Methylbenzotriazol, 5-Methylbenzotriazol,
Beta-Blocker: Metoprolol, Sotalol
X-Ray contrast agents Amidotrizoeacid, Iomeprol, Iopamidol, Iopromid
The concentrations of these substances and its metabolites are under their therapeutically effective concentration after the wastewater treatment, so that these agents are grouped under the concepts micro-contaminants. But the impacts of the micro-contaminants on the environment are already evident. [http://toxsci.oxfordjournals.org/content/106/1/93.short N.Shved et al.] e.g. has shown that 17a-Ethinylestradiol at environmentally relevant concentration is able to influence fish growth and reproductive functions of bony fishes.
The long-term consequences of increasing estrogen concentration for human beings are still largely unknown. Nonetheless, declining sperm counts and thereby increasing infertility in men living in industrial nations may well relate to this hormonal pollution. In addition, [http://bmjopen.bmj.com/content/1/2/e000311.full testicular and prostate cancers] as well as osteoporosis could be a consequence of overly high concentrations of estrogen in the human body. At the moment only the acute, short term effects are obvious, but the long term effects of continuous exposure of ecosystems, nor the effects that occur even below therapeutic levels in non-target organisms are not [http://www.umweltbundesamt.de/chemikalien/veranstaltungen/ws-monitoring-arzneimittel/16_vortrag-abstract_knacker.pdf predictable].
Only for 70 of the [http://www.umweltbundesamt.de/chemikalien/veranstaltungen/ws-monitoring-arzneimittel/11_vortrag-abstract_bergmann.pdf 247] substances sufficient information exist for an ecotoxicological assesment. To assess the risk, the Federal Environment Agency (UBA) published a recommendation for not or only partially assessable micro-contaminants, defined as “Gesundheitlicher Orientierungswert" [http://www.umweltbundesamt.de/chemikalien/veranstaltungen/ws-monitoring-arzneimittel/3_vortrag-abstract_vietoris.pdf GOW]. Some of these recommended values already have been exceeded by several agents, like Diclofenac (up to 10,5µg mL-1) and Iboprofen up to 9,79 µg mL-1).
Detailed concentrations in sewage effluent and surface water of Diclofenac and some other substances can be found here. The increasing amounts of some micro-contaminants, prompted the European Commission to adds [http://www.europarl.europa.eu/meetdocs/2009_2014/documents/envi/pr/909/909091/909091en.pdf 15 new priority substances] to the list of priority hazardous substances:
- six incredients of pesticides (Aclonifen, Bifenox, Cypermethrin, Dicofol, Heptachlor und Quinoxyfen),
- six incredients biocides (Cybtryn, Dichlorvos und Terbutryn),
- two industrial Chemicals (Perfluoroctansulfonat (PFOS) und Hexabromcyclododecan (HBCDD)),
- three pharmaceutical agents (Diclofenac, 17a-Ethinylestradiol (EE2) und Estradiol (E2)) and
- Dioxin and dioxin like polychlorinated Biphenyle (dl-PCB).
This list defines priority substances in the field of water policy, namely chemicals presenting a significant risk to or via the aquatic environment. Besides these 15 substances the European commission plans to [http://www.europarl.europa.eu/meetdocs/2009_2014/documents/envi/pr/909/909091/909091en.pdf increase the priorization of other substances] such as Anthracen, brominated diphenylether, Naphthalene and Polycyclic Aromatic Hydrocarbons.
But ultimately, currently there are no legally binding limits for concentrations of pharmaceutically active compounds in surface water, groundwater or drinking water. Consequently the increasing consumption of pharmaceuticals leads to an increasing pressure on the aquatic environment and on the availability and quality of healthy and clean water. This is the problem the iGEM Team wants to solve. The Bielefeld iGEM team is to developing a biological filter using immobilized laccases to purify municipal and industrial wastewater from synthetic estrogens and other micro-contaminants.
Our Focus
Estradiol:
Estradiol is a natural human hormone secreted not only in women but also in men. It’s importance in women metabolism is that after reaching puppetry this hormone provides being a woman. In men on the other hand Estradiol has been detected to have influence on sperm ejaculation ([http://www.ncbi.nlm.nih.gov/pubmed/8098802]). This hormone has particularly effect on characterization a women for example in breast development, changing body shapes or affecting bones. During the menstrual cycle Estradiol levels fluctuates ([http://aje.oxfordjournals.org/content/175/6/536.long]) indicating it is importance in sexual development.
Since Estradiol is easily degradable by many sort of Enzymes our idea was to test it with our Laccases because it is the basic structure of the synthetic Ethinyl estradiol which is not as easy degradable.
UV-light detection: 230nm Extinction, 310nm Emission
Molecular Mass: 272,39g * mol-1
Chemical structure: C18H24O2
Estrone:
Estrone is one of several natural estrogens. Like Estradiol it is important in several development steps by women. It has been said that Estrogen disordered people has a higher potential for breast cancer ([http://toxnet.nlm.nih.gov/cgi-bin/sis/search/r?dbs+hsdb:@term+@rn+53-16-7]) . Our focus on Estrone was to characterizes Laccases in a wide range of substrates.
UV-light detection: 230nm Extinction, 310nm Emission
Molecular Mass: 270,36g * mol -1
Chemical structure: C18H22O2
Ethinyl estradiol:
Ethinyl estradiol is the synthetic variation of the natural estradiol. It’s structure is constructed so that it is not easily degradable with human enzymes. Anti baby pills used by women contains Ethin estradiol that passes through excrete into wastewater where fishes and other organisms live. This causes several disorders in the natural metabolisms of the organisms ([http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1874224/]) such as womanizing male fishes. The increase of Ethinyl estradiol in wastewater on the past years has made Ethinyl estradiol to a potential problem in the future. But not only fishes also human are affected from this problem because the wastewater from sewage seeps into groundwater and from there into drinking water. Therefore the degradation or filtration of Ethinyl estradiol will become more importance in cleaning water. Activated carbon or ozonation treatment of wastewater could solve this problem but it’s too expensive in practice. Such an activated carbon treatment in England would cost for 250.000 people around $10,3 Million ([http://www.nature.com/nature/journal/v485/n7399/full/485441a.html])
UV-light detection: 230nm Extinction, 310nm Emission
Molekular Mass: 296,4g * mol-1
Chemical structure: C20H24O2
Diclofenac:
Diclofenac is used to treat pain specially in cancer and reaches through the way of wastewater into lakes and drinking water. Since this Chemical is not filterable in sewages without activated carbon or ozonation treatment ([http://www.ncbi.nlm.nih.gov/pubmed/18715709]) Diclofenac and Ethinyl estradiol are becoming more attention from the European Commision for Water ([http://europa.eu/rapid/pressReleasesAction.do?reference=IP/12/88&format=HTML&aged=0&language=EN&guiLanguage=en]). Besides this the there is a concrete example in the sewage plant ([www.schloss-holte-stukenbrock.de]) Schloß-Holte, Diclofenac were detected here in a concentration of 1900ng/L.
UV-light detection: ?
Molecular Mass: 296,148g * mol-1
Chemical structure:C14H10Cl2NO2Na
Ibuprofen:
Ibuprofen is like Diclofenac used by pain treatment such as in rheumatism. The WHO has set Ibuprofen in the list of essential medicine ([http://www.who.int/medicines/publications/essentialmedicines/Updated_sixteenth_adult_list_en.pdf]). According to a medicine study, people who take regularly Ibuprofen have a higher risk becoming kidney cancer ([http://www.bloomberg.com/news/2011-09-12/commonly-used-pain-pills-increase-kidney-cancer-risk-in-study.html]).
UV- light detection: Extinction 224nm, Emission 290nm
Molecular Mass: 206,3g * mol-1
Chemical structure: C13H18O2
Naproxen:
Naproxen is also used in pain treatment. Beside it helpful side Naproxen can cause several side effects such as hoarseness or nausea ([http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0000526/]). Naproxen reaches lakes through the usual way.
UV- light detection: Extinction 232nm, Emission 272nm
Molecular Mass: 230,3g * mol-1
Chemical structure: C14H14O3
Naphthalene:
Commonly used as an intermediate for some chemical synthesis such as insect repellents or fungicides. Naphtalene may destroy red blood cells on overdoses in blood. From industrial use Naphthalenes reaches sewage water and from there lake water where organisms live. Our E. coli laccase was able to degradate Naphtalene ([http://www.ncbi.nlm.nih.gov/pubmed/21120471]). Therefore we used Naphtalene to test it with our other self produced Laccases.
UV-light detection: Extinction 275nm, Emission 350nm
Molecular Mass: 128,17g/mol
Chemical structure: C10H8
Acenaphthene:
This Chemical consisting Naphtalene is used in preparation pesticides and pharmaceuticals and with the same way as the other chemicals it reaches lake water. The effects on organisms are not yet clearly definied. But the E.coli Laccase can degradate Acenaphten ([http://www.ncbi.nlm.nih.gov/pubmed/21120471]).
UV-light detection: Extinction 275nm, Emission 350nm
Molecular Mass: 154,21g * mol-1
Chemical structure: C12H10
Phenanthrene:
It’s name comes from phenyl and anthracene. There is not much information about the effects or interactions in water or organisms in water but the E.coli Laccase was able to degradate this chemical ([http://www.ncbi.nlm.nih.gov/pubmed/21120471]).
UV-light detection: Extinction 275nm, Emission 350nm
Molecular Mass: 178,23g * mol-1
Chemical structure: C14H10<br
Anthracene:
Anthracene is used in producing dyes but the aftereffects are not yet cleared. Because the E.coli Laccase was able to degradate other polycyclic aromatic hydrocarbons we decide to test Anthracene with our produced Laccases.
UV-light detection: Extinction 260nm, Emission 430nm
Molecular Mass: 178,24g * mol-1
Chemical structure: C14H10
Laccase - Our Teammate
In the last few years a lot attention has been drawn to Laccases due to their ability to oxidise both phenolic and nonphenolic lignin related compounds as well as highly recalcitrant environmental pollutants. This makes them very useful for applications concernig several biotechnological processes. This includes the detoxification of industrial effluents, for example the paper and pulp, textile and petrochemical industries, the useage as a tool for medical diagnostics and as a bioremediation agent to clean up herbicides, pesticides and certain explosives in soil.Laccases are also used as catalysts for the manufacture of anti-cancer drugs and even as ingredients in cosmetics[1]. In our project Laccases are used as cleaning agents for a water purification systems. Their capacity to remove xenobiotic substances and produce polymeric products makes them a useful tool for bioremediation purposes."
Laccases are copper-containing polyphenol oxidase enzymes (EC 1.10.3.2) that are found in many plants, insects, microorganisms and mainly in fungi. These enzymes are used in different metabolic pathways and fulfill several functions. E.g. these Enzymes are necessary on the one hand to degrade lignin in Basidiomycetes and on the other hand to synthesize complex polymers like Melanin in Ascomycentes. In general, laccases are extracellular enzymes and consists usually of 15-20 % carbon-hydrogen. The molecular weight of the deglycated protein is 60 to 80 kDa (about 480-650 aminoacids). These enzymes can occur as monomers, dimers, trimers and tetramers. The first crystal structure of a laccase from the organism Trametes versicolorwas published in 2002.
Laccases are able to oxidize a broad range of substrates due to the contained copper-cluster, by reducing oxygen to water. The active site of the enzyme includes a four-copper-ion-cluster, which can be differed by spectroscopically analyses. This Cluster consists of one blue copper-ion (type 1), one type 2 copper ions and two type 3 copper-ions. Because of the blue copper-ion, the laccases belongs to the big family of the blue copper proteins. This specific blue copper ion is essential for the radical oxidation of the phenolic group. In the enzyme-reaction the electron from the oxidation is transferred to the other three copper ions. These ions are forming a trinuclearic cluster, which transfers electrons to the terminal electron acceptor oxygen. The molecular oxygen is reduced by four electrons to water.
[1] Susana Rodríguez Couto & José Luis Toca Herrera;Industrial and biotechnological applications of laccases: A review; 2006; Biotechnology Advances 24 500–513
Laccase-donators
Arabidopsis thaliana
Arabidopsis thaliana (A. thaliana), or commonly known as thale cress, is a small flowering plant which has been established as a model organism. We have chosen this little plant as a representative for higher eukaryotes and not only because there is a lot of research going on at Bielefeld University with this tiny little weed. A thaliana has a small genome with 125 Mb total and was sequenced completely in the year 2000. Besides the good annotation of genes there is also a large number of mutant lines available. The research on A. thaliana is progressing fast and researchers from all around the world are working with this model organism because of its rapid life cycle of 6 weeks and its easy cultivation even at restricted places, just to name a few examples. The Arabidopsis community is therefore huge and progress in understanding the cellular and molecular biology of this flowering plant is documented well and available.
For our project we were interested in the laccase(s) of Arabidopsis. We did some research at [http://www.arabidopsis.org/servlets/Search?type=general&search_action=detail&method=1&show_obsolete=F&name=laccase&sub_type=gene&SEARCH_EXACT=4&SEARCH_CONTAINS=1/ TAIR] and found 22 laccases or laccase-like genes. Stunned by the amount of laccase genes we decided to concentrate on just one which does not encode a laccase-like protein. We have chosen gene [http://www.arabidopsis.org/servlets/TairObject?type=sequence&id=123870/ AT5G48100.1] and investigated further. Our next stop was at the [http://bar.utoronto.ca/efp/cgi-bin/efpWeb.cgi/ eFP Browser] to see where our chosen laccase is expressed. We found out, that it is expressed in the seeds and therefore available in the siliques, as you can see in here:
With this bioinformatic research and the following laboratory work we try to get in contact with a laccase from a higher eukaryote.
Bacillus halodurans
Bacillus halodurans is a Gram-positive rod-shaped bacterium which can be found in the soil. It is motile and able to develop spores. Containing unique genes, sigma factors and OLE RNAs, it can adapt to alkaline or alcoholic environments. It is able to produce a two-peptide lantibiotic called haloduracin which can already be fermented. We found an [http://www.ncbi.nlm.nih.gov/pubmed/15293032 article] in which the authors produced a multicopper oxidase with potential laccase activity. The gene product was able to oxidise 2,2’-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid (ABTS), 2,6-dimethoxyphenol (2,6-DMP), syringaldazine (SGZ). This laccase is interesting for us because its pH-optimum is between 7,5 and 8, so it is closer to the prevailing pH of the wastewater treatment plant (pH 7).
Bacillus pumilus
[http://www.dsmz.de/catalogues/details/culture/DSM-27.html Bacillus pumilus DSM 27 (ATCC 7061)] is one of our bacterial donators for the laccase genes. Bacillus pumilus is also a gram-positive soil bacterium. It is already used for alkaline protease production, in environmental decontamination of dioxins, and in the baking industry. The protein [http://www.ncbi.nlm.nih.gov/protein/ZP_03054403 CotA], which we used is described as spore coat protein. It has a molecular weight of 58,6 kDa. We chose this laccase, because it’s catalytic activity is shown towards 2,2’-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid (ABTS), 2,6-dimethoxyphenol (2,6-DMP), syringaldazine (SGZ) and many other substrates ([http://www.biomedcentral.com/1472-6750/11/9 look here for the publication]). So the enzyme seemed an appropriate laccase for examining the activity on our substrates. For further information on our characterization of CotA (we further call the enzyme BPUL) click here.
Escherichia coli
Another laccase, which catched our attention is the enzyme [http://www.ncbi.nlm.nih.gov/protein/85674340 CueO] from Escherichia coli. The bacterium naturally occurs in human and animal intestine. In laboratory it’s a model organism and the most widely used organism in molecular genetics. The about 1-6 µm long bacterium has a laccase with a high potential for our approaches. It is described that the laccase CueO is able to oxidize different PAHs (polycyclic aromatic hydrocarbons). An oxidation activity for the crude laccase was measured for fluorene, acenaphthylene, phenanthrene and benzo[a]anthracen (Zeng, Lin et al., 2011). The laccase has a predicted molecular weight of 53 kDa. Our aim is to produce and characterize this laccase with regard to the plan to develop a degradation system using immobilized laccases. Our aim is to produce and characterize this laccase with regard to the plan to develop a biological filter using immobilized laccases. Therefore we isolated the laccase CueO from E. coli DE(BL21) out of genomic DNA. For consistently names we call this laccase ecol in our wiki. For further information about our characterization of CueO (ECOL) look here.
Thermus thermophilus
Thermus thermophilus is a gram-negative eubacterium. The bacterium is as the name suggests extremely thermophilic and has an optimal growth temperature at about 65 °C. Due to its cell characteristics this organism can grow on temperatures up to 85 °C. This property are caused by very thermostable proteins which leads to a high interest in many proteins from different Thermus strains for laboratory research. The most famous strain is probably Thermophilus aquaticus which was isolated from water of hot springs. The strain has an interesting polymerase, the widely used Taq polymerase, a very thermostable protein. In our project we are interested in another protein of Thermus thermophilus, called laccase. The first description of the [http://www.ncbi.nlm.nih.gov/pubmed/15999224 Tth-laccase] from T. thermophilus was in the year of 2005. This multi copper blue oxidase (53 kDa), short laccase, shows an oxidative activity on ABTS and SGZ. Like the most proteins of T. thermophilus this enzyme presents a high stability under harsh industrial conditions. Due to its skills and properties our attention was drawn for this laccase. We decided to isolate the sequence from the strain T. Thermophilus HB27 and to develop a degradation system against micro-contaminants using this immobilized laccase.
Trametes versicolor
References
The Arabidopsis Information Resource (TAIR), www.arabidopsis.org/aboutarabidopsis.html, on www.arabidopsis.org, Oct 24, 2000
Winter et al. (2007). Arabidopsis eFP Browser at bar.utoronto.ca. PLosOne 2(8): e718. Reiss, R., J. Ihssen, et al. (2011). "Bacillus pumilus laccase: a heat stable enzyme with a wide substrate spectrum." BMC Biotechnol 11: 9.
Zeng, J., X. Lin, et al. (2011). "Oxidation of polycyclic aromatic hydrocarbons by the bacterial laccase CueO from E. coli." Appl Microbiol Biotechnol 89(6): 1841-1849.
Miyazaki, K. (2005). "A hyperthermophilic laccase from Thermus thermophilus HB27." Extremophiles 9(6): 415-425.
Wallace JG, Zhou Z, Breaker PR (2012). "OLE RNA protects extremophilic bacteria from alcohol toxicity." Nucleic Acids Research 40(14):6898-6907.
Ruijssenaars HJ, Hartmans S (2004). "A cloned Bacillus halodurans multicopper oxidase exhibiting alkaline laccase activity." Applied Genetics and Molecular Biotechnology 65:177-182
Danesh A, Mamo G, Mattiasson B (2011). "Production of haloduracin by Bacillus halodurans using solid-state fermentation." Biotechnology Letters 33(7):1339-44.
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