I am currently attempting to grow a culture of P. Acnes bacteria. Right now, my only hope in identifying colonies of the bacteria in the culture is to use a black light to find colonies that glow orange. I am not sure whether or not this will work since nutrient agar may not provide them with something that helps them produce porphyrins. It's also entirely possible that another form of bacteria contaminating the culture would produce the same effect.

I would like to entertain the possibility of buying a microscope for this project. I have never owned a quality microscope(just toy ones in the past), so I don't really know what type of microscope or what magnification I'll need in order to correctly identify and observe the P. Acnes bacteria.

What would be interesting is if I could turn this into a pharmacological project; if I can verify that I have the correct bacteria(to a fair degree of certainty, anyway), I can see how the bacteria reacts to different chemicals and environments.

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    $\begingroup$ How a bacterium reacts to different chemicals and environments is often more useful in identification that microscopy. It's also cheaper. You may want to look into some differential/selective media and/or biochemical tests. Or just send it away for 16S sequencing. $\endgroup$
    – canadianer
    Feb 10, 2015 at 8:13

1 Answer 1


I agree with canadianer that chemical tests are generally more useful for identification. However, morphology does help and some staining techniques can be useful for identification (the Gram stain is the obvious one). If you are looking for a microscope, look for a nice scope with a 100x oil-immersion objective and a 10x ocular lens (12x would be OK too). Zeiss, Nikon and Olympus are some old names that make good scopes - and there are more.


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