We designed E. coli that have increased biofilm formation speed compared to wild-type by inserting NhaR transcriptional activator. Yet, both of them are also inserted by PETase, a protein that will degrade PET plastic into its smaller monomers.
The production and degradation capacity are modeled to predict when degradation does not occur or reaction rate equals to zero. Hence, we want to test following hypothesis, whether the increased expression of biofilm will support the PET degradation capacity. Our assumptions are as follows: (1) Biofilm which encapsulates E. coli colony act as protection from environment and increase colony concentration inside biofilm, therefore enzyme production will be optimal. (2) Bottom section of E. coli that interacts with the PET interface is not encapsulated by biofilm and the enzyme-substrate complex will work just as fine on this layer.
E. coli without increased biofilm formation is used as comparison to above strain. Without NhaR, this strain will just have normal biofilm formation expression, which will have planktonic forms floating around in the medium. PET degradation will be slower than using +NhaR strain, because we assume that PETase should be diffused into water and affected by Brownian motion, therefore the possibility of PETase-substrate contact will be less than +NhaR strain.
If, somehow, the result of +NhaR strain is significantly lower than its opposite strain, we should conclude that our assumptions is not confirmed to be true.