Sugar Rush explores whether or not E.coli has a preference for any of the five base sugars. The work tries to visualise this chemotaxis by setting up a race in a petri-dish.
Context:The work began by looking at chemotaxis in E.coli. The ability for bacteria to locate food differs between species, where some use their motility to locate food and others employ a sort of self genetic-engineering to alter their shapes. Chemical signals help bacteria in directing it towards a food source. E.coli grows under multiple conditions and is able to metabolise may types of sugar. This work probes the possibility of visualising chemical sugar preferences laying out a petri dish with the five base sugars.
Materials and Methods:Sugar Rushwas setup using five different sugars. Each sugar was weighed in order for each to have the same concentration in moles. For each sugar a food dye was added and the liquid was made solid by using agar. Agar in itself contains sugar so it was important to make the individual sugar out-compete this by making it more potent or concentrated. In addition, there was a need to also make the agar “hard” so each of these bottled contained very solid agar. Once the sugars were autoclaved, a petri-dish containing normal LB-agar was prepared. To get the sugars into the dish, incisions where made with a sterile scalpel and a solid block of agar removed creating 5 whole evenly divided around the circumference of the dish. By heating and liquefying the sugars I would fill each hole with about 300µl of sugar. Once solidified the dish was inoculated with 1µl of liquid bacterial culture. A bit of food colour was added to the culture to help see its inoculation point. I also used engineered bacteria with GFP expression to help trace the growth. The dish was then inoculated over several days allowing the colony to begin staking out its preferred sugar. One of the reasons for using very hard sugar-agar mixture was to minimised diffusion which is an inevitably.
Outcome:Sugar Rush’s relative simple setup ponders our ability to elicit bacteria and observe their preferences. In a gallery space the work is mounted on a wall or table. Using blue light and a filter audience can more easily observe the direction of the colony however it is also visible under normal light.