• Question: How many different types of bacteria are there?

    Asked by 522brna47 to Ciarán on 20 Nov 2014.
    • Photo: Ciarán O'Brien

      Ciarán O'Brien answered on 20 Nov 2014:

      The most correct answer is “Nobody knows yet”. We’ve been searching for bacteria for well over a hundred years now, and we’re still finding different types.

      There’s a database I use called GenBank, which stores all the DNA sequences scientists have found in the bacteria they’ve discovered, so anyone in the world can see them. The best way we have of defining a different type of bacteria is the DNA of its 16s gene. Right now there are about 78,000 different 16s genes available on the GenBank database.

      We still haven’t looked everywhere on the planet, and our technology for sampling bacteria has flaws that could mean they miss a few types, and on top of that bacteria evolve very rapidly, so getting an exact number will probably never be possible 🙂

      Here’s a short article showing some of the problems we have counting the different types of bacteria:

      http://www.newscientist.com/blog/shortsharpscience/2008/06/counting-in-bacterial-world.html

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