Team:Sheffield/Project

From 2014.igem.org

Revision as of 01:32, 18 October 2014 by Emmhaych (Talk | contribs)

Project


Background

We are aiming to degrade the blockages in urban drainage systems that accumulate when fats, oils and greases are disposed of down kitchen sinks, bathrooms or drains. Fats, oils and greases are not particularly harmful to the national sewage system when in liquid form, but as the lipids cool down, they congeal and harden. The solidified lipid material is highly adhesive and sticks to the interior crown of the pipes, restricting the flow of wastewater and causing the pipes to block. The solidified lipid blockages have been nicknamed “fatbergs” by the media. Bleach and detergent use is only a temporary solution and merely cause the fatberg to develop further downstream. The fatbergs have the potential to lead to SSO’s (Sanitary Sewer Overflows), which have the potential to unleash raw sewage and contaminants such as endocrine disruptors, pathogens and pharmaceuticals into the urban environment.


A fatberg found in the sewers beneath Kingston upon Thames in July 2013, was estimated to weigh 15 tonnes and reached the size of a double decker London bus. The fatberg had reduced the flow capacity of the sewer to 5% of it’s normal capacity and had the potential to spurt raw sewage out of manholes across the entirety of Kingston upon Thames. The fatberg damaged 20m of pipes which took Thames Water six weeks to clear and involved the closure of a number of major roads in West London for the duration of the summer.


Water UK estimate that throughout the UK there are approximately 200,000 sewer blockages a year. As many as 75% of the afforementioned blockages are estimated to be caused the inproper disposal of fat, oil and greases. Water UK speculate that the incidence of such blockages is on the increase. The treatment of fatberg blockages costs water companies in the UK millions of pounds every month which is reflecting in the rising cost of water bills in the UK. Key problems resulting from the development of fatbergs include sewer flooding, rat infestations and odour problems.


This problem is not specific to the UK, but is becoming increasingly commonplace in more economically developed countries including the USA and Australia to name but a few. The increasing number of blockages has been linked to the rapid increase in the number of food service establishments in metropolitan areas. Many countries have legal provisions requiring food service establishments dispose of fats, oils and greases through grease interceptors, however, such devices are often insufficiently designed to cope with large volumes of waste material and are incapable of effective FOG separation from the kitchen waste stream.


A related problem we intend to solve is the build up of hair that becomes trapped in plugholes in basins, baths and showers. Hair attracts grease and dirt particulates which build up in drainage systems and restrict the flow of water through pipes. Our project has focused on development of constructs that produce lipase and keratinase enzymes to degrade FOGs and hair. These constructs are designed to sit within a small, under-sink bioreactor that will produce and feed them into the waste system as the sink is drained.

Medal Criteria

Bronze

  • Team registration
  • Complete judging form
  • Team wiki
  • Present a poster and talk at the Jamboree
  • Project descriptions distinguish input from students, advisors, instructors, sponsors and attributors
  • Document at least one new standard BioBrick or device

Silver

  • Experimentally validate one new BioBrick
  • Document characterisation of this part on the part/device registry page
  • Submit new part to the iGEM registry
  • Articulate a question relating to ethics, sustainability, social justice, safety, security or intellectual property

Gold

  • Improved characterisation of an existing BioBrick part or device
  • Help any registered iGEM team
  • Describe and evaluate the teams approach to the research question

Biosensor

Our initial work linked in to a synthetic lipid responsive promoter element, initially submitted to the iGEM Registry in 2012 by a team from WHU-China. The part consists of promoter BBa_J23110 with a FadR binding site placed downstream with a 3bp overlap.
This allows for production of the full length downstream gene or protein, unless the promoter is blocked by the binding of FadR (a bacterial transcription factor). FadR binding is inhibited by long chain fatty acyl-CoA compounds, such as oleic acid.

Enzyme Synthesis

Due to the use of constitutive promoters within this project, enzyme synthesis within the cells would be occurring at all times, given the growth conditions suitable for growth and synthesis of the cell.

Enzyme Secretion

TliA, our heat stable lipase, has been shown to excrete via a Type 1 ABC transporter. Without the exporter, the lipase is sequestered inside the cell. Excretion is necessary for the creation of our design product, as the enzymes need to be removed from the system without damage to the cell culture.

KerUS has been shown to self export in BL21, a strain which it would be feasible for us to use in a mix self culture with other E.coli strains.

Safety

A main focus of our project was to engineer our bacteria in a safe and sustainable way. Because of our focus being on E.coli, we had little to worry about in the way of pathogenicity, and our enzymes were deemed safe as long as standard lab practice was used; gloves, lab coats, no licking the benches.

We were, however, conscious of the fact that our product would be used in a home environment. Kill switches were discusses but seemed over-used and not always effective. A dead cell is just as bad as a live one in an open system where genetic exchange is the main worry. To keep users of our product safe, we aim to keep our system closed and bacteria removed from the system on a monthly basis by disinfection with bleach.