Part:BBa_K2572016

pLux-PhlF

We found the part effective and expression was detected when the inducer AHL was added at a concentration of 10^-9 or higher.

We need to convert the signal to a negative response, since we want to initiate the expression when density is low, which we done this by adding a PhlF repressor, combine together, it is the part K2572016. PhlF binds to an operator in the pPhlF region to repress the expression of downstream suicide sequences (ccdB/GBSV1/colicin E2). When temperature and cell density are high, regulator PhlF (and sRNA) is produced to repress the expression of suicide genes. As temperature drops and community density decreases, simulating that engineered strains escape from the fermentation condition, PhlF is repressed and consequently turns on the expression of cytotoxic sequences.

Also a model was built to predict the function of this device. You can visithttp://2018.igem.org/Team:RDFZ-China/Model to check it out. We proposed a deterministic ordinary differential equation set, which is sufficient to describe the quorum sensing regulation of a bacteria population. By using numerical methods to simultaneously solve these three concise and easily comprehensible modelling equations, we have successfully derived at a concentration interval for the amount of extracellular acyl homoserine lactone required in the fermenter in order to maintain a high enough concentration of PhlF protein to suppress the expression of nuclease and maintain the survival of engineered bacteria both at the start of and during the fermentation process. The result from Matlab simulation,1E-10M [AHL] corresponds well with that from wet lab experiments,1E-9M [AHL]. Using the experimental data, we adjusted the model, concluded that the difference might be the effect of plasmid copy number. We will improve the model according to the data, and come out with an acceptable concentration range. This information would be handy for workers at the fermentation industry to ensure their biosafety-directed bacteria to always survive inside the fermenter.

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  COMPATIBLE WITH RFC[21]
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  COMPATIBLE WITH RFC[1000]