Geosmin–Mother Earths perfume!!

Posted: May 8, 2013 in Uncategorized



Geosmin–Mother Earths perfume!!

1)Its an organic compound.

2)PETRICHOR- is the scent of rain on dry earth.;petra-stone; ichor, the fluid that flows in the veins of the gods in Greek mythology. It is defined as “the distinctive scent which accompanies the first rain after a long warm dry spell”.

3)Human Nose is extraordinarily sensitive to the compound GEOSMIN.

4)Geosmin is produced by several classes of microbes, including cyanobacteria and actinobacteria (especially Streptomyces), and released when these microbes die.

5) Communities whose water supplies depend on surface water can periodically experience episodes of unpleasant-tasting water when a sharp drop in the population of these bacteria releases geosmin into the local water supply. Under acidic conditions, geosmin decomposes into odorless substances.

6)In 2006, the biosynthesis of geosmin by a bifunctional Streptomyces coelicolor enzyme was unravelled. A single enzyme, geosmin synthaseconverts farnesyl diphosphate to geosmin in a two-step reaction.

7)Streptomyces coelicolor is the model representative of a group of soil-dwelling bacteria with a complex life cycle involving mycelial growth and spore formation. Besides the production of volatile geosmin, it also produces many other complex molecules of pharmacological interest; its genomesequence is available at the Sanger Institute.

8)Geosmin is responsible for the earthy taste of beets and a contributor to the strong scent that occurs in the air when rain falls after a dry spell of weather (petrichor) or when soil is disturbed.

9)The human nose is extremely sensitive to geosmin and is able to detect it at concentrations as low as 5 parts per trillion.

10)Geosmin is responsible for the muddy smell in bottom-dwelling freshwater fish such as carp and catfish. Cyanobacteria produce geosmin and 2-methylisoborneol, which concentrate in the skin and dark muscle tissue. Geosmin breaks down in acid conditions; hence vinegar and other acidic ingredients in fish recipes help reduce the muddy flavor.

11)The smell after a rainstorm is also attributed to geosmin. (The smell before the rain is ozone.)

12)Geosmin has an exceptionally low detection threshold of the order of 10-100 ppt.

13)Besides its pleasant, characteristic earthy aroma,geosmin is also associated with an undesirable musty odor or off flavor in drinking water, as well as in wine, fish, and other food stuffs, making its detection and elimination important in the management of water and food quality.

14)What could be the role of a metabolite like geosmin? Surely it cannot be just to give wine and water a different taste. There are a number of hypotheses. Some think it may be for defensive reasons: produce a pong and predators will steer clear from their prey. But geosmin could also be a sly way of promoting sporulation. The particular fragrance let off by geosmin usually occurs where humidity is involved. Camels may well smell out an oasis by sniffing the air for traces of the fragrant metabolite. While camels quench their thirst, hordes of Streptomyces spores will be supped with the water or will find a way to stick onto the animals’ hides. In this way, spores can be carried for miles. In the same way, some cacti flowers may also use the geosmin scent to fool insects, in a sort of fragrant mimicry. Indeed, insects are attracted to the plants in the hope of a little refreshment, and in their quest for water, they actually serve as pollinators!

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