Team:TU Delft/Project/alkane-degradation/results

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Alkane Degradation Results & Conclusions

Figure 1. – Schematic description of the alkane degradation pathway with the corresponding genes.

Characterization of the alkane hydroxylase system (AlkB2-system)

From the ratios hexadecane/undecane obtained from GC chromatograms, we may conclude that the samples obtained from the E.coli strain, carrying the AH system, contain relatively less octane than the control strain. By comparing peak ratios we were able to estimate the specific enzymatic activity of the system, which was found to be 0.045 U/mg.

For more information about our findings, read the detailed alkane hydroxylase results page.

Figure 2. Enzyme activity [U/mg total protein] of alkane hydroxylase system as compared to the negative control E.coli K12 strain

Characterization of the long-chain alkane monooxygenase (LadA)

The analysis of the obtained GC graphs allowed us to estimate the enzymatic activity. We observed a significant increase in enzyme activity in the strains carrying the ladA protein generator compared to the negative control strain. The highest enzyme activity value was found to be 3.33E-03 U/mg protein. In order to know more about the characterization of this system, read the detailed LadA results page.

Figure 3. Enzyme activity [U/mg lysate] of the alkane monooxygenase LadA as compared to the negative control E.coli K12 strain

Characterization of Alcohol Dehydrogenase (ADH)

According to our results, the E. coli cell extract has a dodecanol-1 dehydrogenase activity of 9.64e-12 kat/mg (0.58 mU/mg); whereas our recombinant strain expressing the Biobrick [http://partsregistry.org/Part:BBa_K398018 BBa_K398018] has an activity of 2.93e-11 kat/mg (1.76 mU/mg), an improvement of 2-fold compared to the wild type activity; which also means 3% of the activity of the positive control Pseudomonas putida.

If you are interested in knowing more about our findings, read the detailed ADH results page.

Figure 4. Comparison between E. coli ADH activity and our recombinant strain.

Characterization of Aldehyde Dehydrogenase (ALDH)

Our results suggest that the recombinant strains E. coli 029A and E. coli 030A functionally express our biobricks. The expression of ALDH under the promoter-rbs combination [http://partsregistry.org/Part:BBa_J13002 BBa_J23100]-[http://partsregistry.org/Part:BBa_J13002 BBa_J61117] increases the dodecanal dehydrogenase activity in E. coli cell extracts 2-fold; whereas the expression of the same protein using the part [http://partsregistry.org/Part:BBa_J13002 BBa_J13002] as promoter-rbs combo increases the same activity 3-fold.

Moreover, the enzymatic activities measured for the constructs [http://partsregistry.org/Part:BBa_K398029 BBa_K398029] and [http://partsregistry.org/Part:BBa_K398030 BBa_K398030] were equivalent to 33.98% and 42.01% of the Pseudomonas putida aldehyde dehydrogenase activity, respectively.

If you want to know more about of our findings, read the detailed ALDH results page.

It is worthy to mention that our part expresses the protein in a lower amount, meaning that cells express a highly active protein. Thus the cellular resources are spent in a more efficient way than in the strain that overproduces ALDH.

Figure 5. Comparison of ALDH activities in the different strains tested in this study

References

Kato T. et al. "Gene cloning and characterization of an aldehyde dehydrogenase from long-chain alkane-degrading Geobacillus thermoleovorans B23" Extremophiles (2010) 14:33-39.
http://mbel.kaist.ac.kr/lab/research/protein_en1.html
Hoffmann F. and Rinas U. "Stress Induced by Recombinant Protein Production in Escherichia coli" Advances in Biochemical Engineering/Biotechnology, 2004, Vol. 89/2004, pp. 73-92.

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 <html><center><img src="https://static.igem.org/mediawiki/2010/0/00/TU_Delft_project_navigation.jpg" usemap="#projectnavigation" border="0" /></center><map id="projectnavigation" name="projectnavigation"><area shape="rect" alt="Characterization" title="" coords="309,3,591,45" href="https://2010.igem.org/Team:TU_Delft#page=Project/alkane-degradation/characterization" target="" /><area shape="rect" alt="Results" title="" coords="609,3,891,44" href="https://2010.igem.org/Team:TU_Delft#page=Project/alkane-degradation/results" target="" /><area shape="rect" alt="Parts" title="" coords="9,3,290,44" href="https://2010.igem.org/Team:TU_Delft#page=Project/alkane-degradation/parts" target="" /></map></html>
 ==Alkane Degradation Results & Conclusions==
-[[Image:TUDelft_Alkane_degradation_route.png|600px|thumb|center|'''Figure 1''' – Schematic description of the alkane degradation pathway with the corresponding genes.]]
+[[Image:TUDelft_Alkane_degradation_route.png|600px|thumb|center|'''Figure 1.''' – Schematic description of the alkane degradation pathway with the corresponding genes.]]
-===Alkane hydroxylase (AH) system===
+===[https://2010.igem.org/Team:TU_Delft/Project/alkane-degradation/results/alkane_hydroxylase Characterization of the alkane hydroxylase system (AlkB2-system)]===
-===LadA===
-===ADH===
-==== Growth on alcohols as sole carbon source====
+From the ratios hexadecane/undecane obtained from GC chromatograms, we may conclude that the samples obtained from the ''E.coli'' strain, carrying the AH system, contain relatively less octane than the control strain. By comparing peak ratios we were able to estimate the specific enzymatic activity of the system, which was found to be 0.045 U/mg.
-As in the case of alkane monooxygenases, our first attempt was to grow our recombinant strains on long-chain alcohols and aldehydes; hoping that E. coli will do the further degradation steps. For that purpose, we used octanol-1 and dodecanol-1 for the ADH system; whereas we used octanal and dodecanal for the ALDH system.  If everything goes well, we should see microbial growth on minimal medium with these compounds as sole carbon source.
-==== Resting cell assays====
-Our second attempt was to grow cells, until the exponential phase is reached; then the cells were collected and the spent medium was changed for a buffer with glucose that lacked of N-source, this was done in order to avoid more biomass production. Additionally we added alcohols and aldehydes to the mixture, so that if our part is working they will be converted in other molecules: alcohols to aldehydes and aldehydes to alkanoic acids.
-With this approach, we are hoping that the enzymes produced during the growth phase will remain inside the cells. The glucose added will serve for maintenance purposes and co-factor regeneration. If everything works well, there will be some nice peaks appearing on our GC analysis.
+For more information about our findings, read the [[Team:TU_Delft/Project/alkane-degradation/results/alkane_hydroxylase|detailed alkane hydroxylase results]] page.
-==== NADH production in cell extracts====
+[[Image:TUDelft_AlkB2_Total.png|600px|thumb|center|'''Figure 2.''' Enzyme activity [U/mg total protein] of alkane hydroxylase system as compared to the negative control ''E.coli'' K12 strain]]
-We called this assay: THE LAST RESOURCE  =s
-Basically, we grew cells until an O.D. (600nm) between 0.5-1.0. We needed chubby healthy happy exponential-growth cells because most of our constructions are meant for protein production in this growth phase.
+===[https://2010.igem.org/Team:TU_Delft/Project/alkane-degradation/results/LadA Characterization of the long-chain alkane monooxygenase (LadA)]===
-Once, we got a lot of cells... we disrupted them by sonication and we analyze the NADH production by their guts using a simple spectrophotometrical analysis. If our parts are working, we should see a higher NADH production when the substrate (dodecanol-1 or dodecanal) to the buffer with microbial guts and NAD buffer. We can use this method  because NAD is the natural co-factor of our proteins. Fortunately for us, NAD reduction could be easily quantified by absorbance measurements at 340 nm.
+The analysis of the obtained GC graphs allowed us to estimate the enzymatic activity. We observed a significant increase in enzyme activity in the strains carrying the ladA protein generator compared to the negative control strain. The highest enzyme activity value was found to be 3.33E-03 U/mg protein. In order to know more about the characterization of this system, read the [[Team:TU_Delft/Project/alkane-degradation/results/LadA|detailed LadA results]] page.
-We called this protocol "the last resource" because the others didn't work. Which means that alcohols and aldehydes do not cross the cell membrane, thus in order to grow cell on these compounds as sole carbon sources... WE NEEDED TO ADD TRANSPORTERS =(
+[[Image:TUDelft_LadA Total.png|600px|thumb|center|'''Figure 3.''' Enzyme activity [U/mg lysate] of the alkane monooxygenase LadA as compared to the negative control ''E.coli'' K12 strain]]
-ADH was tested with Dodecanol (C12)
+===[https://2010.igem.org/Team:TU_Delft/Project/alkane-degradation/results/ADH Characterization of Alcohol Dehydrogenase (ADH)]===
+According to our results, the ''E. coli'' cell extract has a dodecanol-1 dehydrogenase activity of 9.64e-12 kat/mg (0.58 mU/mg); whereas our recombinant strain expressing the Biobrick  [http://partsregistry.org/Part:BBa_K398018 BBa_K398018] has an activity of 2.93e-11 kat/mg (1.76 mU/mg), an improvement of 2-fold compared to the wild type activity; which also means 3% of the activity of the positive control ''Pseudomonas putida''.
-This yielded the following results:
+If you are interested in knowing more about our findings, read the [[Team:TU_Delft/Project/alkane-degradation/results/ADH|detailed ADH results]] page.
-[[Image:TUDelftADH results.jpg|600px|thumb|center|'''Figure 1''' – The results of a resting cell assay done on BioBrick BBa_K398018.]]
+[[Image:TUDelftADH_final.jpg|600px|thumb|center|'''Figure 4.''' Comparison between E. coli ADH activity and our recombinant strain. ]]
+===[https://2010.igem.org/Team:TU_Delft/Project/alkane-degradation/results/ALDH Characterization of Aldehyde Dehydrogenase (ALDH)]===
-{| style="color:black; background-color:white;" cellpadding="5" cellspacing="0" border="1"
+Our results suggest that the recombinant strains ''E. coli'' 029A and ''E. coli'' 030A functionally express our biobricks. The expression of ALDH under the promoter-rbs combination [http://partsregistry.org/Part:BBa_J13002 BBa_J23100]-[http://partsregistry.org/Part:BBa_J13002 BBa_J61117] increases the dodecanal dehydrogenase activity in ''E. coli'' cell extracts 2-fold; whereas the expression of the same protein using the part [http://partsregistry.org/Part:BBa_J13002 BBa_J13002] as promoter-rbs combo increases the same activity 3-fold.
-|Conditions
-|'''Native'''
-|'''Native'''
-|'''Heated'''
-|'''Heated'''
-|-
-|Sample
-|J13002
-|K398018
-|J13002
-|K398018
-|-
-|Total protein in well
-|3.303E-02
-|3.180E-02
-|7.351E-03
-|7.994E-03
-|-
-|Specific activity (kat/mg)
-|1.812E-11
-|2.606E-11
-|0.000E-00
-|5.041E-12
-|}
-This shows two things.
+Moreover, the enzymatic activities measured for the constructs [http://partsregistry.org/Part:BBa_K398029 BBa_K398029] and [http://partsregistry.org/Part:BBa_K398030 BBa_K398030] were equivalent to 33.98% and 42.01% of the ''Pseudomonas putida'' aldehyde dehydrogenase activity, respectively.
-That E.Coli is partly able to degrade Dodecanol on it's own. And that this activity is greatly increased (43.83% normalized for the amount of protein) with the addition of the ADH gene.
-It is also clear that eventhough ADH is from a thermophilic organism it loses most (63.5%) of it's activity after heating. the raw data for these calculations can be seen below.
-(Although this decrease in activity could also be attributed to the host organism lacking the proper post translational modifications.)
-===ALDH===
+If you want to know more about of our findings, read the [[Team:TU_Delft/Project/alkane-degradation/results/ALDH|detailed ALDH results]] page.
-==== Growth on alcohols as sole carbon source====
+It is worthy to mention that our part expresses the protein in a lower amount, meaning that cells express a highly active protein. Thus the cellular resources are spent in a more efficient way than in the strain that overproduces ALDH.
-As in the case of alkane monooxygenases, our first attempt was to grow our recombinant strains on long-chain alcohols and aldehydes; hoping that E. coli will do the further degradation steps. For that purpose, we used octanol-1 and dodecanol-1 for the ADH system; whereas we used octanal and dodecanal for the ALDH system.  If everything goes well, we should see microbial growth on minimal medium with these compounds as sole carbon source.
-==== Resting cell assays====
-Our second attempt was to grow cells, until the exponential phase is reached; then the cells were collected and the spent medium was changed for a buffer with glucose that lacked of N-source, this was done in order to avoid more biomass production. Additionally we added alcohols and aldehydes to the mixture, so that if our part is working they will be converted in other molecules: alcohols to aldehydes and aldehydes to alkanoic acids.
-With this approach, we are hoping that the enzymes produced during the growth phase will remain inside the cells. The glucose added will serve for maintenance purposes and co-factor regeneration. If everything works well, there will be some nice peaks appearing on our GC analysis.
+[[Image:TUDelftALDH_final.jpg|600px|thumb|center|'''Figure 5.''' Comparison of ALDH activities in the different strains tested in this study]]
-==== NADH production in cell extracts====
-We called this assay: THE LAST RESOURCE  =s
-Basically, we grew cells until an O.D. (600nm) between 0.5-1.0. We needed chubby healthy happy exponential-growth cells because most of our constructions are meant for protein production in this growth phase.
+===References===
+#Kato T. et al. "Gene cloning and characterization of an aldehyde dehydrogenase from long-chain alkane-degrading ''Geobacillus thermoleovorans'' B23" Extremophiles (2010) 14:33-39.
+#http://mbel.kaist.ac.kr/lab/research/protein_en1.html
+#Hoffmann F. and Rinas U. "Stress Induced by Recombinant Protein Production in ''Escherichia coli''" Advances in Biochemical Engineering/Biotechnology, 2004, Vol. 89/2004, pp. 73-92.
-Once, we got a lot of cells... we disrupted them by sonication and we analyze the NADH production by their guts using a simple spectrophotometrical analysis. If our parts are working, we should see a higher NADH production when the substrate (dodecanol-1 or dodecanal) to the buffer with microbial guts and NAD buffer. We can use this method  because NAD is the natural co-factor of our proteins. Fortunately for us, NAD reduction could be easily quantified by absorbance measurements at 340 nm.
-We called this protocol "the last resource" because the others didn't work. Which means that alcohols and aldehydes do not cross the cell membrane, thus in order to grow cell on these compounds as sole carbon sources... WE NEEDED TO ADD TRANSPORTERS =(
 <html><center><img src="https://static.igem.org/mediawiki/2010/0/00/TU_Delft_project_navigation.jpg" usemap="#projectnavigation" border="0" /></center><map id="projectnavigation" name="projectnavigation"><area shape="rect" alt="Characterization" title="" coords="309,3,591,45" href="https://2010.igem.org/Team:TU_Delft#page=Project/alkane-degradation/characterization" target="" /><area shape="rect" alt="Results" title="" coords="609,3,891,44" href="https://2010.igem.org/Team:TU_Delft#page=Project/alkane-degradation/results" target="" /><area shape="rect" alt="Parts" title="" coords="9,3,290,44" href="https://2010.igem.org/Team:TU_Delft#page=Project/alkane-degradation/parts" target="" /></map></html>