Team:ITB INDONESIA/post-wetlab
RhamCOLIpid
Engineered E. coli producing rhamnolipid for green enhanced oil recovery
Post Wetlab Modelling
Model
We developed a new system where the rhlAB enzymes are simply under T7 promoter with lac operator. We would like to grow our RhamCOLIpid in an autoinduction media as described by Li et al (2011). In the media, there will be glucose and lactose, so the carbon preference will occur. We model our production using t=0 as the time when lactose is started to be consumed and therefore activated native Lac promoter to produce T7 polymerase and eventually produce rhamnolipid .
Now, the concentration of lactose is high enough to remove Lac I and the E. coli can start to produce T7. We use this event as the beginning of the model, and we conclude that the lactose act as the activator for this reaction. Also at this event, we assume that every Lac I has been removed from all of the Lac operator, including the one at pT7.
First we need to create the mathematical model for the production rate of T7. Using hill function for activator, we can model the T7 as:
After we finished the model for T7, we create the model for transcription rate of the mRNA RHL A&B. Assuming that for every pT7 exist an operator and it can only produce rhl A&B when it is supplied by T7, we can use hill function for activator as the base for the mathematical model for mRNA_(rhl A&B):
We create model for rhl A&B by using linier model. We assume that rhl A&B is only affected by mRNA and the degradation rate.
To model the production rate of HAA, we use mass action law. The change rate of HAA is affected by the fatty acid and rhamnolipid. The concentration of HAA will increase because HAA is produced by fatty acid but it will decrease because it was used to produce rhamnolipid .
v1 is the production rate of HAA from two fatty acid, from this information we can use hill function with hill constant=2 because we need two fatty acid to produce one HAA and v2 is the production rate of Rhamnolipid from HAA and we can use michaelis-menten equation for this rate. We assume that the concentration of rhl A=rhl B = 0.5 * rhl A&B and fatty acid is constantly available. So we have this model:
For the last model we have two substrate kinetics and one product. For this reaction, we assume that the rhamnose is constant but it is not saturating B and fatty acid is constantly available. So we can use steady state kinetics with some modification from Michaelis-Menten equation:
We tested our model and it showed that production of T7 polymerase, rhlA & rhlB enzymes production, and eventually rhamnolipid production behaves as we expected.
