Archive for the ‘Exercises’ Category

Competition! QuestionI/GroupB: The Dead Sea halophiles

Wednesday 10 October, 2007

Here is a question to group B third-year students, since students from group A have already answered yesterday’s question:

Find the name of a halophilic microorganism (a bacterium or preferably an archaeon) that has been isolated from the Dead Sea (البحر الميّت)…

Send the answer (name + source of information) by email or bring it in person. The fastest three will have prizes (of course, if the answer is correct!)

Competition! QuestionI/GroupA: What’s the microbe that withstands high radiation dose?

Tuesday 9 October, 2007

Find the name of a bacterium that can live in high radiation and is currently studied to be used for radioactive waste cleaning.

Send the answer (name + source of information) by email or bring it in person. The fastest three will have prizes (only if the answer is correct!)

Staph pigments competition: Three winners already!

Monday 2 April, 2007

We already have three winners for the Staph pigments competition.

The winners are
1) Samar Galal Ahmed Kabeel (سمر جلال أحمد قابيل) emailed the right answer at 4:28 PM, Cairo Time
2) Mohammed Shehta Mostafa (محمد شحتة عبد النبي مصطفى) posted the right answer at 9:02 PM, Cairo Time
3) Soha Khairy ElMekkawy (سهى خيري المكاوي) handed out a full answer at 3:30 PM, Cairo Time, in the laboratory.

All others, please keep sending your answers.

Staph pigments: Three weeks-no answer? Now there is a prize!

Friday 30 March, 2007

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. This surprises me because many people visit the weblog everyday and comment on other posts. In addition, a simple Google search will reveal the answer; so…?!

OK. I will not post the answer yet. I will give you another week. This time, there is an incentive: a prize!
The first three who email me the correct answer will be eligible to win. Alternatively, you can write the answer on a piece of paper and bring it to me in person in the laboratory on Monday April 2nd at 3 pm or Wednesday April 4th at 4 pm.

Condition: I will discuss with you how you got the answer. If you fail to explain how you exactly found it, or I realize that you received it from someone else: no prize!!

Staph aureus: is the color just ornamental?

Wednesday 7 March, 2007

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?

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