Finding extremophilic microorganisms
Dr Adele Williamson from The University of Waikato explains the challenges to finding and identifying microorganisms living in extreme environments like the Dry Valleys in Antarctica.
Discovering microorganisms traditionally has involved scientists culturing them in a laboratory. As the science community develops new techniques and technology to explore organisms living in extreme environments, the applications and knowledge about biological processes also grow. This is a field of science that is challenging thinking and finding new organisms with benefits that could be very useful for everyday applications in the future.
Find out more about Dr Adele Williamson’s research in these articles:
Transcript
Dr Adele Williamson
It’s about the last 30 or 40 years that scientists have understood that there are actually microorganisms in Antarctica. This mistake was due to our bias towards culturable bacteria and our understanding that we only find bacteria that we can culture.
The origins of microbiology come from cultivation-dependent methods. This is bacteria that we can grow. So this is things like E. coli, this is things like some of our pathogens. This is this classical experiment where you might get a cotton bud and wipe your toilet bowl and then streak it out onto some agar and look at all the stuff that pops up. That’s cultivation because we can see it with our eyes when you get large amounts of the bacteria growing, and we can also see the increase in cell numbers if we watch that sample over time.
Most of the bacteria that live in Antarctica can’t be cultivated using the methods that we know about. And there’s a couple of reasons for that. One of the reasons is that they live in quite complex communities – so one bacterium relies on its buddies to be able to survive – and the other reason is that these are growing in an environment which is very different to what we would usually use to cultivate bacteria. Think about what you’ve got to do to cultivate a pathogen which grows in the human body: 37°, very high nutrient levels and very high density with no friends except for its own kind because it’s used to sort of taking over this environment.
That’s a very different situation to what you’re looking at if you’re trying to cultivate a microbe from Antarctica, which is growing on very little nutrients in a very changeable environment and is not dividing very quickly because the opportunities it has – whether conditions are good enough for it to be able to grow and divide – don’t come around that often, so these are very, very slow growing. For that reason, scientists couldn’t actually cultivate them in the lab for a very long time and still most of them can’t be cultivated, and it was only with the advent of molecular technologies – in particular, PCR – that scientists were able to go to Antarctica, do PCR, look for some of the key genes that we know are in bacteria and realise that those are actually living in these environments.
Acknowledgements
Shelly Brandt, The University of Waikato
Time-lapses of scientists at campsite and from the McMurdo Dry Valleys in Antarctica, Keith Heyward and Jennifer Berglund, Prehensile Productions
Dr Susie Wood, Cawthron Institute
Bacterial colony growth on agar plate time-lapse, pouria6889. CC BY 3.0
Dr Jane Mullaney
