Hello, I am doing an Independent Research project for my Microbio class. I am wondering where specifically to find M. Luteus? I found that it's found in the normal flora of the skin and in soil, but not any specifics. Any help? I need to get it as isolated as possible too.

Hello, I am doing an Independent Research project for my Microbio class. I am wondering where specifically to find M. Luteus? I found that it's found in the normal flora of the skin and in soil, but not any specifics. Any help? I need to get it as isolated as possible too.

What does the "M." stand for?

Miccrococcus - It's the genus.

Edited October 13, 201411 yr by assanater601

Micrococcus - It's the genus.

So you have to find it first, and isolate it. How are you going to do that, has it got some distinctive features on a culture plate?

http://en.wikipedia.org/wiki/Micrococcus_luteus

So it can be found on your skin. Shouldn't be hard to find. Don't shower for a few days then swab your skin.

Nitpick: if it is for class you should italicize species and genus , whereas genus is capitalized but not the species identifier: Micrococcus luteus. It is also customary to write the name in full once, before using abbreviations, though E. coli is famous enough to not to do it.

M. luteus is, as you already mentioned found in different habitats. What specifically would you like to know? They have been found in skin swabs from different body parts, especially areas rich with sweat glands, but also to some extent in the upper respiratory tract.

Nitpick: if it is for class you should italicize species and genus , whereas genus is capitalized but not the species identifier: Micrococcus luteus. It is also customary to write the name in full once, before using abbreviations, though E. coli is famous enough to not to do it.

M. luteus is, as you already mentioned found in different habitats. What specifically would you like to know? They have been found in skin swabs from different body parts, especially areas rich with sweat glands, but also to some extent in the upper respiratory tract.

How exactly to get a sample. Just take a swab under the armit? Or maybe in the back of the throat?

Yes that would work, though there are a lot of other bacteria there, too, I would avoid the throat, especially as you may cultivate pathogens. That is also a general issue, i.e. there is always a certain risk that some pathogens may be enriched while you try to isolate something from human samples. So you should get some feedback about safety before trying it out. That being said, you can try to get micrococci from part of the skin (often used parts include forehead, cheek, parts of arms etc) though they may not always be M. luteus (or micrococci at all for that matter, as you obviously have also plenty of other skin dwellers). IIRC M. varians is also quite dominant and expected to be present in rather high proportions.

As mentioned above, M. luteus is part of the normal human flora. In our medical microbiology lab we isolate it very often, especially during MRSA screening tests because it also dwells in the nasopharynx and as mentioned above colonizes all the respiratory tract.

M. luteus grows well and fast (you can see its colonies after a period of 24 hours incubation) on TSBA and CNA agars, as well as on Chocolate agar. As its name indicates, the bacterium has a yellow pigmentation which you can easily notice while observing the colonies.

I must add that it is being often confused with Staphylococcus aureus colonies, mainly because of their pigmentation. But while S. aureus has a golden or slightly yellow pigmentation, M. luteus has a bright yellow one.

 

* As you may already know, S. aureus is also part of the normal human flora (~80% of the population carry it in the nasopharynx. so you can easilly isolate them both), so in order to be 100% sure that you deal with M. luteus and not with S. aureus I advise to do the following:

1.) Compare their pigmentation as noticed above.

2.) Gram-stain the suspected colonies: S. aureus (and also other Staphylococci) is a Gram positive coccus which clusters to form a grape-cluster shape, while M. luteus is a Gram positive coccus which tends to form quadruplets.

3.) S. aureus is coagulase positive and DNAse positive, while M. luteus isn't.

 

Hope I helped!

Today I have noticed several M. luteus colonies on TSBA 5%. You can easily spot the bright yellow bacteria among coagulase negative Staphilococci, which are white (see attachment).

This culture was obtained from a vaginal swab.