Why do some bacteria kill each other? And how do they do that? It's really a mind-blowing thing if you think about it. Please give me a simple answer.

  • $\begingroup$ Welcome. Have you done any research yourself?. I'm mod and cannot vote as such, but I would close it on the basis of underresearchedness. Adding prior research provides focus to your question. The post is too broad, which in turn attracts poor answers (and a lot of mod work :) $\endgroup$
    – AliceD
    Commented Oct 17, 2018 at 7:53

1 Answer 1


They do that because a bacterium contains all the molecules required for life, that is they are a source of amino acids, lipids, glucids and nucleic acids. This is the same reason why we eat in the first place: we need a source of these molecules to survive or, in other words, to allow our cells to carry out their tasks such as replicating the DNA or producing proteins.

Bacteria can kill other bacteria by a kind of infection: the predator bacterium enters a bigger prey and then start consuming the prey's molecules. By the same token, Mycobacterium tuberculosis enters the macrophages and used them for its own biochemistry, for instance.

Interestingly, this process of bacterial predation is under scrutiny for the development of a new breed of antiseptics in the age of antibiotic resistance (see https://phys.org/news/2017-03-predatory-bacteria-antibiotic.html).

  • $\begingroup$ Is it really always inside out? Couldn't a bigger bacteria eat and digest the smaller one? $\endgroup$
    – Roger V.
    Commented Jun 18, 2021 at 14:33

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