IGEM:Imperial/2010/Water sanitation and cell population control

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Water Sanitation and cell population control

  • Detection system
  • Treatment system

Detection system

Possible inputs:

  • Pathogenic bacteria

(But Heidelberg did something similar to this in 2008...) If we can detect the N-acyl homoserine lactone produced by V. cholerae, we might be able to get a response from a downstream pathway?

  • Protists

(E. histolytica causes dysentery and is ingested as cysts. Diamond et al (1972, 1979) researched two viruses which were able to lyse cells. Possible way of killing them? Or we could try to make the cysts aggregate and then remove them?)

  • Viruses
  • Heavy metals

(but cells must be immobilised/easy to remove)

  • Chemicals

Have a look at this review for information about how some bacteria metabolise hydrocarbons!

I think our best bet here is to use the XylR protein, which is already in the parts registry. There's also the TodST protein which senses toluene. Both of these regulatory proteins are involved in degradation pathways of their respective compounds, and so we might be able to use something downstream to activate a response?

  • VOCs
  • Helminths

This is an area that we'd really like to look into. This article shows that some parasitic worm eggs need signals from gut bacteria in order to hatch. But is there a downstream signaling pathway in bacteria when their fimbriae attach to eg parasitic worm's egg?? Are there any bacterial receptors that sense anything on the surface of parasites? Or a metabolite produced by a parasite?

Possible outputs:

  • Fluorescent proteins (colour depends on what is detected)
  • Odor (smell depends on what is detected)

There is also evidence that Salmonella and and Schistosoma species interact using pilli (Link). This paper gives loads of information about the expression of fimbriae proteins and how fimbriae are assembled. It also hints about the downstream pathways, but not in much detail...

Also the parasite Mansonella perstans needs an endosymbiont - a Wolbachia species - to survive and be virulent (Paper 1Paper 2). Unfortunately no information about the molecular mechanism of this interaction is given.

Treatment system

  • System used depends on result from detection system
  • Phage lysins for G +ve bacteria
  • RNA interference

Population control

Use quorum sensing to keep the population below a threshold level

Biofilm or free bacteria?


  • Could have mutually dependent bacteria, so that if one detaches, it can't survive without the other
  • Higher throughput?

Free bacteria

  • More applicable to domestic treatment?
  • This looks more plausible for testing in remote areas, so we'll most likely go down this route.