• Question: Are any bacteria made of more than one cell?

    Asked by Ana María to Eoin, Ester, Ildiko, Natasha, Paul, Tom on 6 Nov 2017.
    • Photo: Ester Gil Vazquez

      Ester Gil Vazquez answered on 6 Nov 2017:

      Some bacteria organize themselves in multicellular structures (similar to how the cells of our body organize forming tissues like the skin). If you want to see how this looks like google “multicellular filamentous cyanobacteria”. Like it happens in our bodies, these cells are able to communicate with each other and delegate functions. This is not the trend in the bacteria world though, but an exception. Most bacteria function as individual cells.

    • Photo: Natasha Myhill

      Natasha Myhill answered on 6 Nov 2017:

      Bacteria are always unicellular but as Ester says, they are really clever at talking to each other and can act as one big structure. Another example of this is called a biofilm. Some bacteria can make these by attaching to a surface (e.g. skin or lung tissue), then others stick on top, and then more, e.t.c. – They can then all release a coating which covers the biofilm and makes it hard for the body to get rid of the bacteria.

      What is really cool is that some genes in the bacteria are only switched on when there are enough of them – this is a system called quorum-sensing. So a few bacteria on their own can’t release a toxin for example, but when there are more of them together, the gene will be switched on and they can all release the toxin.

    • Photo: Eoin McKinney

      Eoin McKinney answered on 6 Nov 2017:

      Great question – it depends on how we define “made of”. Some stick together in clumps but that doesn’t really mean they’re multicellular. To be considered properly multicellular, they need to do a bit more than that. Some important functions of multicellular organisms include their ability to stick together but also for the cells to communicate with each other, be dependent on each other and to share out the tasks that need to be done (a bit like your brain and muscles share the workload). Not many bacteria fit this definition but the filamentous cyanobacteria are the best example.

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