Wednesday, January 7, 2009 - 01:55
I don't know if any DIY biologists are looking for projects, but I think engineering yeast with a gene to detect heavy metals might be a good DIY biology project and I have some ideas for how to do this. What are the advantages of using yeast and working on this kind of problem?
- This could have a socially beneficial result. Contamination of soils, water, and even toys with heavy metals like lead, arsenic, and others, is a growing problem. If DIY biologists could make a cheap test, it could be helpful for a large number of people.
- Yeast, at least the ones I'm thinking about, Saccharomyces cerevisiae, are not pathogens and the GFP protein isn't harmful. If we can sell fish with GFP at Walmart, brewer's yeast with GFP shouldn't be anything of environmental threat.
- You can use amino acids to select the engineered yeast, thus avoiding issues with antibiotic resistance genes.
- Yeast are easy to store and easy to ship. I regularly buy dried packets of yeast at the grocery store
- There are some existing examples for doing this. Mike Barnkob pointed me to a wonderful example yesterday from the IGEM competition where the 2006 University of Edinburgh IGEM team made sensors for arsenic.
Figure 1. My drawing outlining how to engineer yeast to produce GFP in the presence of heavy metalsHere's what the yeast look like when they're making GFP:
Figure 2. Yeast producing GFPWhat are the disadvantages of this method?
- We need a bit more information. Unfortunately, in the papers I read, it looked like the transcription factors that activate the metallothinein promoter are best characterized in terms of binding to copper (1). I know metallothinein expression can be turned on in mammalian cells by cadmium, arsenic, and other metals, but I'm not sure about yeast. It might be okay to have an all purpose metal sensor, but this requires more literature research.
- It's harder to get DNA into yeast than into E. coli
- If you really wanted to test this, you need to find some heavy metals or contaminated soil. I think for a proof of concept test, though, you could spread some yeast on a penny and see if that makes it light up.