Thank you to David Jordan at Living Physics for the support. All mistakes are solely mine.
So, I tested 280nm UV light on baker’s yeast.
This was a ‘minimal trust’ investigation into wet lab experiments, to learn the subtleties of UV susceptibility data that I wouldn’t get by reading. My conclusion is that there are lots of sources of variability. It’s helped me calibrate myself on how fragile lab experiments can be in real world settings.
My main takeaways were:
it’s not easy to calculate the UV dose applied to an organism. In my setup, I found it pretty complicated, there is likely to be error across labs. I am wondering if there should be standardised UV dose methodology within the community. When I read papers from others that calculate their dose, there is a lot of math and a lot of assumptions. The amount of degrees of freedom here worry me.
sterilising your environment is very hard, and I really need to lock in in terms of improving the wet lab setup that I have at home. I also expect that for people doing independent science in general, that this is going to be a challenge. So in my next post, I’m going to try write more about sterile technique for home labs, and think this will be helpful for people experimenting with any type of biology with little experience.
I think the upside in doing independent experiments yourself is big. I learnt a bunch about sources of variability in experiments that wasn’t initially clear to me in the beginning. One big thing that could’ve happened would be if this experiment didn’t show any result at all. But, it did and I’m going to go through the first set of results. I’m lucky to be completely independent, so I don’t need to lie about the subtleties and can just say everything without worrying about whether its successful.
The Results
Here are the yeast colonies that grew after different doses of UV light, shown in the black text below each image. Whilst the samples are contaminated, you can see that there is a rough reduction in the colony density as we increase the dose. The third sample in the middle got completely contaminated, which is why you can’t see anything there (I wonder why…)
At this point, I didn’t bother doing the exact count because I’m planning to do a repeat of this experiment under better conditions, which I will write more on below. But, the initial run looks kind of promising. The first thing that I find kind of surprising is that the 1300mJ / cm^2 dose level didn’t completely eradicate the colonies, contrary to some papers I read that lead me to believe that I would have complete eradication at this level of dose. But again, I’ll tell you why these data anomalies might’ve occurred if you read on! :)
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