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From 2013hs.igem.org

Contents 1 Home 2 Project 2.1 Parts 2.1.1 Operon 1 2.1.2 Operon 2 2.1.3 Operon 3 3 The Team 3.1 Paul 3.2 Joe 4 Notebook

Home

This year, a team of students from St Paul’s School, London, has decided to take up the challenge of competing in the IGEM competition - the first to represent the UK at High School Level. Our aim is to mutate E.coli to create a semi-quantitative lactose detector; we intend to create three mutant operons on a single plasmid, with each operon responding to a different concentration of lactose in the environment the E.coli finds itself in.

We plan to use red, yellow and green fluorescent proteins in a “traffic light” system, whereby the colour of the protein translated corresponds to the concentration of lactose, with red fluorescent protein denoting a high concentration of lactose, yellow fluorescent protein representing a low concentration of lactose and green fluorescent protein showing that there is no lactose present in the immediate environment the E.coli is exposed to. It is our hope that this could potentially be used in allergy testing and in the analysis of food samples, and by individuals who are lactose intolerant; because we hope to design a semi-quantitative detector it will show a spectrum of lactose concentrations so mild intolerants and severe intolerants will be able to use the sensor in different ways.

So far we have been designing our project and selecting appropriate biobricks for use in each operon. We have also been using the 3A assembly kit to practice assembling biobricks on a plasmid backbone. During the past year, the team has also been involved in a plasmid mutagenesis project to modify T4 bacteriophage lysozyme, and in so doing we have practiced many of the lab techniques needed for biobrick assembly.

Project

The school team is aiming to create a semi-quantitative detector for lactose, a sugar molecule which causes intolerance in 9% Caucasians, and between 70-90% in Asians and Africans. It is most commonly found in milk and dairy products and intolerance has been linked to recent over consumption of milk and dairy, particularly in Europe and North America. Individuals who are lactose intolerant have an insufficient lactase concentrations in their digestive tract. As a result they are unable to hydrolyse lactose into galactose and glucose. As a result these disaccharide lactose molecules pass straight through the small intestine and into the colon. Bacteria in the colon can hydrolyse and then metabolise lactose and their anaerobic respiration of lactose produces C02 and CH4 in the colon. This leads to the bloated feeling and symptoms associated with intolerance. Unabsorbed glucose and galactose monosaccharides in the colon also reduce water potential in the colon leading to an influx of water and hence diarrhea.

We hope to go some way to fix this problem but providing the mechanism for a lactose detector. This should enable lactose intolerants to better decide what food produce to eat and help them avoid painful symptoms of intolerance. Furthermore the semi-quantitative nature of the project should enable people with a range of different tolerance levels to be catered for by the sensor; so individuals with higher lactose tolerance can eat more lactose rich food, but individuals with low tolerance can avoid it altogether.

Parts

Operon 1

Operon 2

Operon 3

The Team

Notebook