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Last year I read a course in biology. During that course I learnt that Protozoa like Lamblia intestinalis or Entamoeba hystolitica form cysts in unfavourable conditions.

This year I read a course in microbiology. I learnt that bacteria like Clostridium perfringens or Bacillus anthracis form spores in unfavourable conditions. So far so good. But then I learnt that prokaryotic Borrelia burgdorferi can form a cyst, not a spore.

Firstly, I would highly appreciate any comments that would cast some light on these terms.

Secondly, I would also like to know if the spore inside, say, B.anthracis is the same organism as B.anthracis that produced the spore. Does a spore and the bacteria that produced it have the same DNA sequence? In other words, if I were a sporeforming bacteria, would my spore be myself, my bodypart or my child?

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  • $\begingroup$ I'd like to draw your attention (if you haven't already seen it) to the comments by Souvik - I've edited my answer a bit, but hopefully someone more knowledgeable will come in. $\endgroup$
    – blep
    Commented Jun 4, 2015 at 17:09
  • $\begingroup$ I am in a biology course right now and am learning a lot from it. A spore is all the important parts of the cell gathered up and get cased up like a hard-shelled suitcase.This spore can survive and reproduce when the right conditions come up. $\endgroup$
    – user27300
    Commented Oct 24, 2016 at 20:17

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The bacterial spores you are referring to are called endospores. The spore is formed during unfavorable conditions, by duplication of the bacterial chromosomes, and consequent envelopment by various membranes and protective coatings (while still within the original cell). The spore is dormant and remains so as the outer cell degrades during harsh conditions, releasing the spore. I guess I'd call the spore a clone of the original?

You may enjoy reading the relevant sections in this book, which go into greater detail.

edit: as Souvik has pointed out, this is only one type of "protective" spore. Actinomycetes also form spores, via differentiation of the cells, and cyanobacteria form akinetes also via differentiation (but this structure is not as durable as endospores).

Information about cyst formation is difficult to find, but in bacteria it appears to develop via changes in cell wall composition.

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    $\begingroup$ @ddr3 why are you referring to only a specific sub-group of bacterial spores??....I am a li'l rusty on this section...but as far as I know akinetes & actinomycetes also form spores...which are not endospores.... $\endgroup$
    – souvik bhattacharya
    Commented Jun 4, 2015 at 13:52
  • $\begingroup$ @souvikbhattacharya ah, I missed that on the page. I think I've conflated two different things - I'll try to edit my answer but I'm not an expert on this topic. Please feel free to edit it as well. $\endgroup$
    – blep
    Commented Jun 4, 2015 at 16:44
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dd3 summed up the 1st part of your q nicely.....now 'bout the second part...bacterial spore-s (not necessarily endospores only...but akinets & spores produced by actinomycets) are produced by simple mitosis...so the genetic make-up stays the same as the parent cell.....so if you were a spore-forming bacteria, the spore would be essentially you..in scientific jargon...your "clone"...

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Well, certain bacteria form endospores to tide over unfavourable circumstances. The bacterial cell withdraws its contents so as to form a spherical-shaped mass. This spherical mass is still covered by the original cell wall of the bacterium. This microscopic rounded body covered by the cell wall is called a endospore(endo : inside).It is just like a tortoise tucking its body into its shell. Some other bacteria , to overcome unfavourable conditions develop a hard, protective covering called cyst around themselves. When the conditions become favourable, the cyst ruptures and the bacterium emerges, grows and reproduces. In this case, the bacterium forms a protective covering, while in the former, the cell wall is the protective covering. That, young man, is the difference between a spore and a cyst.

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    $\begingroup$ Thank you for your explanation. I am wondering now if in order to form an endospore a bacterial cell has to withdraw all of its contents. Bacillus anthracis has an endospore within itself. This endospore is less than the bacteria surrounding it. What is more, this bacteria is still active while having an endospore within. $\endgroup$
    – Teiko Abe
    Commented Sep 20, 2015 at 7:26
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A spore is the reproductive part having a protective covering as a spore for its germination has to face harsh environmental conditions such as air currents whereas cyst is the group of cells which come together to protect themselves from harsh conditions. Cyst has nothing to do with the reproduction of the cell.

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  • $\begingroup$ Welcome to Bio. A reference would be appreciated to allow for background reading. $\endgroup$
    – AliceD ♦
    Commented Nov 26, 2015 at 17:45

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