Over the last few months I have been researching yeast with the Zegerman Lab at the Gurdon Institute in Cambridge, as part of ‘Experiments in Art & Science’, a collaboration that brings three contemporary artists to the Gurdon Institute in partnership with Kettle’s Yard, Cambridge.
Led by Dr. Philip Zegerman, the lab uses Saccharomyces cerevisiae, also known as baker’s yeast, as a tool to investigate in detail how the information in genes is copied and transmitted from cell to daughter cell in a very accurate process called DNA replication needed for cells division. I am interested in the ‘liveness’ of dough as a biological material containing yeast and bacteria. It is never static, but consistently growing and morphing. Over the last few years, I have been developing works using dough as a material. In my performances the dough interacts with the human body becoming more yeasty and alive through contact with the human body and the surrounding air.
This work stemmed from my residency in 2016 at Site Gallery, where I developed Fold and Stretch (2016) a performance inspired by the choreography of making bread and its relationship to the body, movement and dance with baker Martha Brown from Forge Bakehouse, Sheffield and choreographer, Lucy Suggate.
When developing this work I shadowed the staff at the bakery, learning the process of bread making incorporating some of these observed movements and timings into the final work. All the bread made at Forge Bakehouse is made using a sourdough starter, which is a combination of wild yeasts and bacteria. I acquired my sourdough starter from Martha during my residency in 2016, and named it Steve. It lives in my fridge at home. I occasionally bake bread with ‘Steve’ and to keep it alive I feed it flour and water in equal quantities.
Phil from the Gurdon Institute also has a sourdough culture (that doesn’t have a name) that he has had for about four years. It came from his lab neighbour Iris who brought it back from Germany. Over the years, he has added powdered store-bought yeast to it so who knows what’s in it from the original culture.
In February 2018, Phil and I decided to find out what microorganisms are in our two sourdough cultures, so we conducted the following experiment.
Under sterile conditions to make sure there are no contaminations, we streaked the samples of sourdough culture on to specially prepared plates to separate out the microorganisms to study the resulting colonies which grew on the plates. Each sourdough culture was streaked onto two different microbiology mediums: YPD (yeast extract peptone dextrose), which favours yeast growth and LB (lysogeny broth), which favours bacterial growth. The plates then went into 30oC incubator.
After a four-day incubation period we observed colonies of microorganisms growing across the plates. Colony morphology key allows scientists to identify microorganisms according to the characteristics of individual colony. Following this key we identified eighteen different colonies of yeast and bacteria. We then picked the colonies that we identified to be yeast cells from each sourdough culture and streaked the cells onto YPD plates. These went into the 30oC incubator to grow.
When we returned to the lab the next day, Phil’s culture had grown substantially overnight and you could clearly see what we think were yeast colonies, however mine didn’t really grow. One reason for this could be that the yeast in ‘Steve’ is dependent on all the other microorganisms which coexist around it to grow and survive, whereas the yeast in Phil’s sourdough culture will happily survive on its own. I then worked with Phil to extract the DNA from the two sourdough cultures. DNA is present in all living organisms, it is the carrier of genetic information and is species-specific. We spun the overnight cultures of yeast/ bacteria and then broke down the cell walls mechanically using glass beads and chemically in the presence of a strong detergent (to enhance the rupture of the cells) and phenol (to keep the DNA in solution).
After spinning these samples again in a centrifuge, we removed the phenol and then concentrated the DNA by precipitation, a process of formation of a solid which was suspended in a liquid. After spinning again, the sample (which is now mainly nucleic acids, including DNA) was washed in 70% ethanol and then solubilised in a small volume of buffer containing RNAse enzyme, an enzyme which removes the main contaminating nucleic acid so that we should be left with only DNA. This was incubated at 37oC for 1 hour leaving only a DNA solution.
DNA samples from both sourdough cultures were visualised on equipment in the lab, and the results absolutely confirm the presence of Saccharomyces cerevisiae (the most common species of budding yeast aka baker’s yeast aka brewer’s yeast) in the single colony cultures. Further tests would need to be done to confirm the presence of other species of microorganisms, for example other wild yeasts or bacteria such as E. coli.
Join artists and scientists from the Gurdon Institute for a day of hands-on activities and talks that showcase their latest art and science collaborations on 12 May at Kettle’s Yard. Click here to find out more.