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Currently I am writing a lab report on the enumeration of bacteria. E.coli takes about 30 mins to double. That is going from 1 bacteria to 2 bacteria.

I want to know which bacteria takes the longest to double? Do some bacteria take a day to double?

Thank you for the help.

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    $\begingroup$ We encourage you to do some research on your own and then ask questions based on what you learned (ideally with references to reliable sources). For homework questions this is required and they must also be correctly tagged. In addition, growth is highly dependent on conditions, so this question is not really answerable as currently formulated. ——— Please also take the time to go through the help pages starting with How to Ask questions effectively on this site and then edit your question accordingly. Thanks! 😊 $\endgroup$ – tyersome Oct 25 at 2:59
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    $\begingroup$ @JoeHealey — Please read the purpose of comments. They are to ask for clarification or suggest improvements, and explicitly not to provide answers, partial or otherwise. $\endgroup$ – David Oct 25 at 8:06
  • $\begingroup$ I am not an expert here by any means but I'll bet that Mycobacterium tuberculosis, the causative agent of tuberculosis, is 'right up there' with a double time of 15-20 hours (ref). In comparison, E.coli is about 20 min. Historically, this was of critical importance in the search for a cure for tuberculosis. See, for example, The Greatest Story Never Told by Frank Ryan $\endgroup$ – user1136 Oct 28 at 12:39
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    $\begingroup$ 3000 years plus seems a little longer than 15 hours. $\endgroup$ – iayork Oct 28 at 15:00
  • $\begingroup$ MTB was literally my suggestion but was deleted by the mods for being in the comments. Nice to know SO's fully even moderation strategy is alive and well -_- $\endgroup$ – Joe Healey Nov 3 at 10:21
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There is no answer to your question

The doubling time of a bacterium is dependent on the conditions: primarily on the temperature and the availability of nutrients, but other factors can apply. Because of this, the doubling time of any particular bacterial strain cannot be considered in the abstract, thus to give a single number we can consider the optimum doubling time for a strain instead - i.e. how fast it will double under the perfect (for it) temperature and nutritional conditions. For the E. coli strain you worked with, this is likely 37 degrees and in a rich media such as Lysogeny Broth. But for the staggeringly vast array of bacteria out there, we simply don't know what the optimum conditions are much less have actually measured growth under them. In fact, there are many bacteria which are known about, but currently uncultured so we haven't even begun to understand their growth dynamics.

So even the simplified question of longest optimal doubling time cannot be answered because we don't have the data for so, so many bacteria. The question of the maximum time between divisions is even less clear: there are bacteria that live under conditions of extreme nutritional limitation that can take thousands of years to double, and strains that can exist as spores for at least 100,000 years and maybe even tens of millions. Do we consider their doubling time to be a 100,000 years? 25 million years? Without specifying the conditions under which the doubling takes place, the question is poorly defined.

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