Staph aureus: is the color just ornamental?

You have all seen in last week’s lab how Staphylococcus aureus produces the characteristic golden yellow pigment that gave this species its name (aureus: web definitions). Have you wondered why the pathogenic staphylococci produce this pigment unlike other species that are not professional pathogens and whose colonies have different colors?
As a matter of fact, scientists working in the field of microbial pathogenesis have also been curious about this golden pigment, and it was very recently that they reached some plausible answers.

Golden pigment-producing staphylococci (left) cause mouse skin lesion unlike non-golden colonies (right).

Try to find out how this golden pigment can help staphylococci overcome the human defenses- Make a guess before you find the answer in literature. The answer is not in textbooks yet! You have to find it by searching scientific literature: check, for example, PUBMED, or… how about Google Scholar?

The answer will be posted in this weblog next week month. You can always click on the “comments” link below these lines and post whatever you found. All you need is to put your email address, which will be kept private. I prefer that you put your name and serial number as well- but it is not a condition.


  • What do you know about pigments in general from your pharmacognosy classes?
  • What do you know about golden pigments in general? In food products?

4 Responses to “Staph aureus: is the color just ornamental?”

  1. Staph Pigments: Three weeks -no answer? Now there is a prize! « Learning Microbiology and Immunology Says:

    […] a prize! Three weeks ago, exactly on March 7th 2007, I have posed a question related to the pigements of Staphylococcus aureus. Until now, I have not received a single comment–not even a question–about that post. […]

  2. s.positive Says:

    dear Dr Ramy

    i read that scientists suggest that anti biotic which can impair the golden pigment can be effective against S.aureus,
    could this (theoritically) be done by modifing the oxidation potential of the carotenoid pigment and (thus decreasing its affinity towards electons to be lower than the bacterial structure it protects) ??
    this a suggestion i thought about in the biochemistery lecture about redox potential!

  3. Sara Fouad (555) Says:

    I have found that the gloden colour of staphylococcus aureus (Gloden armor) acts as an antioxidant. It inhibits the oxidative property of the immunity and so has higher infectivity.

    The golden colour help it resist killing by neutrophils, white blood cells with a front line role in immune defense against invading microbes.

    This is the proof: “The UCSD team used a molecular genetic approach for their studies, knocking out the genes for carotenoid synthesis to generate a mutant strain of Staph that appeared white in color instead of the normal gold.

    “We found that the nonpigmented Staph mutant became much more susceptible to oxidants such as hydrogen peroxide and singlet oxygen produced by neutrophils,” said George Liu, M.D., Ph.D., a research fellow in the UCSD department of pediatrics who spearheaded the studies. “Without its golden pigment, the Staph lost its ability to survive in human neutrophils or blood, and could no longer form an abscess when injected into the skin of experimental mice.”


    btw: I always thought of microbiology as boring (sorry) but now i totally changed my opinion!!
    Thank you Dr.Ramy

  4. One more link between peas and carrots! « It’s a MicrobeFul World! Says:

    […] } Remember the carotenoids? These antioxidants that also let golden staphylococci resist phagocytosis […]

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