Why does petroleum have a rainbow-like reflection in the sunlight?

When the light strikes a thin film of a fluid(such as petrol) in which light moves slower than air, there is an initial reflection off of the surface. Some of the light is transmitted into the fluid and it reflects off the bottom and then finally travels back out.

These waves take slightly longer to reflect due to the travel of a very short distance through the oil, they are now slightly out of phase with the initial reflection, creating a rainbow of interference

And this phenomenon is known as thin-film interference.

Microbiology helps in fighting toothdecay!

Personal Blog of IfuM

One of my classmates suggested that, "You should try finding out some organisms which degrades the calculus or tartar(white stuff which usually is formed on the teeth.) and later you can extract the enzyme responsible for this degradation and make mouthwash with it." And I said "You cannot cure tooth problems by microbiology, that IMPOSSIBLE!"

I have got teeth problems for a long time. I always used to wonder that whether microorganisms can be used to cure/heal all my teeth problems. Turns out there are ways in which scientists have been trying to achieve it.

What causes tooth decay? Bacteria are present on teeth. These bacteria convert sugar to lactic acid, sugar can be obtained from any source of food which you eat and it sticks/remains on your teeth. The lactic acid produced causes tooth decay.

Streptococcus mutans which is a facultatively anaerobic, Gram-positive coccus-shaped bacteria. It is most commonly found in the human oral cavity and is a significant contributor to tooth decay.

So a group of scientists have engineered a genetically mutated strain of Streptococcus which do not produce lactic acid. But you may think, what about the rest of the normal flora? no worries because this strain also produces antibiotics which kill/inhibit the lactic acid producing bacteria!

Genetically altered strain of S. mutans is also called SMaRT. It is engineered to have an advantage over native S. mutans strains. It produces minute amounts of a lantibiotic that kills off the native strains but leaves the SMaRT strain unharmed.

Dont get to excited though you may not get rid of toothbrush anytime soon (:

Cysteine proteases for meat tenderisation - actinidin, bromelain, papain.

Article by Mufaddal IfuM Dewaswala

Have you ever cooked raw meat which was brought home directly from the butcher? It is very tough to cook, if it isnt tenderized. There are various ways of tenderizing the meat eg. mechanical tenderization, dry aging, marinating etc

But one of the classic ways which people follow is putting the meat in pieces of raw papaya for a few hours. I used to always question myself how does it help, well the answer is below!

Raw papaya has high amounts of an enzyme called 'papain'. It is a cysteine protease i.e. they break down proteins by a common catalytic mechanism that involves a nucleophilic cysteine thiol in a catalytic dyad. So basically when it is kept with meat this enzyme acts on it and breaks down the proteins in the meat and thus tenderizing it.

Now a days animals are injected with enzymes like papain before a few mins of slaughter so that the enzyme gets uniformly distributed in the body.

Enzymes which are cysteine protease are papain from papaya, bromelain from pineapple and actinidin from kiwifruit.

Sweet Smell of First Rain - Petrichor

Article by IfuM

Whenever it rains do you notice a different type of smell? It is a very pleasant smell and it is due many reasons and one of them is bacteria! The scent of rain on dry earth is also known as "Petrichor", the word is constructed from Greek.

The smell is due to a gram-positive bacteria of the group 'Actinomycetes'. They usually grow in soil when the conditions are warm. The bacteria produces spores when the soil dries out. When it rains due to the force of rainfall these spores rise above the ground where the moisture acts as an aerosol. We breathe these moist spores in and get that pleasant smell.

We do not smell it all the time because the bacteria leave the spores when the conditions are not dry. These bacteria are very common and are found in all parts of the world and it is usually known as sweet after the rain smell.

And there you go Microbiology has been made easy again ! Likes needed:D