Water Colicin Cleaner: disinfected water by E. coli

We have designed and implemented a biological alternative for the disinfection of contaminated water.

We demonstrate the antimicrobial effectiveness of colicin G, colicin H and microcin C51. These proteins are produced and used naturally by the bacteria to compete with related bacteria killing them in a specific way.

Lysed bacteria (blue areas) upon addition of bacteriocin over an enterobacteria lawn

Polypeptides activity is dependent on three-dimensional structure, based on it, we want to control their activity by changing the pH of the water, for this reason, we have work on the cyanobacterium Synechocystis sp. PCC6803, which is capable of altering the pH as a result of its growth and proliferation on carbon dioxide and light. On top of this, we have performed this on a low-cost photobiorreactor.

pH change upon activation and inactivation of light due to the activity of the cyanobacteria

In order to eliminate pathogenic bacteria from contaminated water, we have designed a system of pipes, membranes and pumps using our engineering knowledge, allowing effectively and safely contaminated water disinfection.

Last, but not least, we have modelled all these behaviours so to have insight on what variables are relevant and which were less important.

Project description

As you can see in the above animation, prototype is split into two different functional parts, each one with a different culture inside a flask and the final part, a vessel that contains the water that has to be purified:

1. Bacteriocin production system

In this compartment, genetically modified E. Coli produce a specific bacteriocin. After some time of peptide synthesis, the entire culture medium, including the bacterias, is driven by a peristaltic pump into the Module of Bacteriocin Separation (MoBS). Once there, the flow is separated into two; most of it returns back to the original flask and a small amount of water passes the ultrafiltration membrane. This permeate is rich in bacteriocins and other small molecules that have gone through the membrane, where bacterias and other big molecules are not able to pass through the pores. After the membrane, the filtered stream falls down through a small plastic funnel into the container that is full of contaminated water and needs to be disinfected.

2. pH stat

The aim of this part, the controller of pH (CopH), is to regulate the pH during the disinfection process to ensure that peptides just work at the desired moment. For this, we use a cyanobacteria that are able to raise the pH when they are illuminated. pH can reach high values (around 9) which inhibit the peptides activity. After some time under absence of light these cells can modify pH values to gain previous ones. In other words, once there are enough peptides in the final container to wipe out the target pathogen culture we can modify pH to active the peptides and start disinfection. The transient of protons to the final vessel is carried out by a dialysis membrane which keeps the cyanobacteria separated from the rest of the set-up.

3. Drink vessel

It is the vessel containing the water with pathogens, where bacteriocins end up. Wait some time and you will get your clean water!

We encourage you to know more about how this prototype has been built, picking up the different parts.