Revision as of 19:37, 25 May 2012 by Cqian (Talk | contribs)

Week 1 (May 1-4)

Week 2 (May 7-11)


For the decarboxylation sub-project, the second week was entirely focused on literature research and the practice of basic laboratory techniques. 8 potential pathways were identified as potential candidates for naphthenic acid decarboxylation. The first of these would utilize only the University of Washington's "PetroBrick" (from iGEM 2011), consisting of the genes encoding the enzymes acyl-ACP reductase (AAR) and aldehyde decarbonylase (ADC). We have planned to verify the PetroBrick in the distribution plates and test its efficacy on naphthenic acids in the coming weeks. If this proves to be unsuccessful, we will begin investigating the alternative approaches, beginning with replacing AAR with carboxylic acid reductase (CAR) from Nocardia iowensis, a very unspecific reductase shown to work on structures resembling naphthenic acids. Failing this, the remaining pathways will be examined; however, the disadvantage in these pathways is their direct reliance on the success of the other steps, as the naphthenic acids must be degraded to the point of resembling branched-chain fatty acids (since all remaining pathways are related to fatty acid metabolism).


In the first two weeks of iGEM our group has focused on reviewing literature regarding the bioremediation of nitrogen groups attached to naphthenic acids. The most prevalent N heterocycle is carbazole, representing 75% of total nitrogen by mass. The upper pathway of carbazole biodegradation is catalyzed by the enzymes coded for by the car operon, CarA (CarAaAbAd), CarB (CarBaBb), and CarC. These enzymes convert carbazole to anthralinic acid. The lower pathway is catalyzed by the enzymes of the ant operon, antA, B, and C, yielding cathecol while releasing CO2 and NH3. The car and ant operons are both regulated by the Pant regulator which is induced by the protein, antR. CarAa also has its own promoter which is not induced by antR. We have also investigated an alternative pathway using CarA combined with an amidase (amdA) that selectively cleaves NH2 from an intermediate of the car pathway. This could bypass much of the car/ant pathway and is possibly more efficient.

We have decided to use Pseudomonas resinovorans and Rhodococcus erythropolis to amplify these genes from. CarABC and AntABC from P. resinovorans has been shown to have a wide range of nitrogen containing substrate specificity. R. erythropolis contains the amdA gene that we wish to use, and some evidence suggests that it may also be able to degrade sulfur rings through its CarABC pathway.

In addition to our research we have also been learning some of the lab techniques we will be using this summer. This includes transforming a plasmid into E. coli, plating and selecting for bacteria containing the plasmid, verifying with colony PCR, performing a mini-prep and a restriction digest.


Things we did.

Ring Cleavage

Things we did.

Week 3 (May 14-18)


The third week included some additional literature investigation in the first two days. The iGEM distributions arrived this week, and verification began on May 17th by transformation into E. coli, followed by colony PCR on May 18th (using standard protocols on the wiki). Additionally, primers were designed for CAR in N. iowensis, along with primers for Nocardia posphopantetheine transferase (NPT), a second enzyme required for optimal function in the former, and a short list of contacts were acquired to request the donation of the required strain (called NRRL 5646) from researchers who have worked with it previously. A sort of form email was drafted for this purpose, and should this be unsuccessful, we will be purchasing the strain from DSMZ ( In the following week, we will begin with development of overnight cultures and gel preparation.

Week 4 (May 22-25)


This week we devised a protocol for biobricking the hpaC and started our lab work. The PCR performed on dry hpaC containing plasmids was not successful so we have to repeat the PCR. We also need to transform E.coli with these plasmids in the next week in order to make sure we wont lose all the plasmids in case the PCR was not successful again. We ordered the substrates we are going to use. Once the substrates and the Rhodococcus strain arrive we are going to test how effectively the bacteria can desulfurize different compounds.


Bioinformatics tool recommend

FMM (From Metabolite to Metabolite) is a critical tool for synthetic biology. FMM can reconstruct metabolic pathways form one metabolite to the other one.

This webpage runs the software that performs the enumeration of all pathways for target compounds in KEGG. More precisely, the desired KEGG compound is submitted in order to get the map of all pathways connecting the compound to metabolites endogenous to E. coli. Optionally, the full map containing the supplements can also be requested.

DNA Designer 2.0 is a Drag and drop standalone software, runs on Windos, MacOS.

DNADesign is a Web-based application

Constraint-based flux analysis - modeling microorganism metabolic network and perform flux analysis.
The metabolic network is translated in to a matrix and then the simulation will calculate a pathway that optimizes the goal (max biomass or max production). The network will be reconstructed (gene/reaction can be added or deleted) to enhance the expected pathway to degrade target compounds. The media (compounds, thermo-conditions) will be manipulated to find the best condition(s) that satisfy the microorganisms to digest the target compounds and reach a good growth rate (say above threshold).