If I have bacteria diluted in water and I centrifuge at max speed for 15-30 min, it is possible that I break the walls so the DNA can scape and I do not get any DNA pellet? or should I get it as a pellet everything togheter (lipids, proteins..) even if the mixure is just bacteria diluted in water?

  • $\begingroup$ At which relative centrifugation force (the "g number") do you work? And: Do you use plain water or do you add anything else? Where do these bacteria come from? $\endgroup$ – Chris Jan 16 '17 at 6:08
  • $\begingroup$ I recommend using a proper extraction kit. It may be possible (I mean anything can damage a cell wall) but you may not obtain a high yield. $\endgroup$ – A. Radek Martinez Jan 19 '17 at 17:38

Not with bench centrifuges. Bacteria have cell wall and are rather small. This gives the cell wall alot of strength. I am not even sure that ultra centrifuges would work.

What you will likely get is a cell pellet. If you want DNA, pellet the cell and either go for direct PCR or sequencing. Or use a DNA extraction kit to obtain the DNA you want.

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  • $\begingroup$ yes I use an ultra centrifuge. I am try to up-concentrate the sample but I cannot see any pellet and even when I remove volume and I resuspend the nonvisible pellet, I do real time pcr and it shows the sample was not up-concentrate, any idea why could that happen? $\endgroup$ – Bio Jan 15 '17 at 22:58
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    $\begingroup$ Why aren't you just lysing the cells first? Centrifugation isn't sufficient to lyse bacterial culture to a great degree. $\endgroup$ – Joe Healey Jan 15 '17 at 23:30
  • $\begingroup$ Because I use bacteria direclty to do real time PCR. $\endgroup$ – Bio Jan 16 '17 at 8:47
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    $\begingroup$ Why? You will get more accurate qPCR results with pure DNA anyway. People only normally do colony PCR from whole cells directly as it's a quick and dirty method for checking for transformants and so on. I've never heard of anyone doing qPCR from culture, and I can't really think why you would want to? $\endgroup$ – Joe Healey Jan 16 '17 at 14:18
  • $\begingroup$ because we use samples directly from a collector but maybe we could try to extract as you say. Thanks! $\endgroup$ – Bio Jan 19 '17 at 9:36

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