2,4,6-trinitrophenol, better known as picric acid, has a well-developed chemistry. Picric acid, (also known as TNP) is a yellow crystalline solid. It is mainly used for explosive, in steel etching and textiles industries. Exposure to picric acid leads to irritation of eyes & skin, sensitization dermatitis, yellow-stained hair, skin, lassitude (weakness, exhaustion), myalgia, anuria, polyuria, bitter taste, gastrointestinal disturbance, hepatitis, hematuria (blood in the urine), albuminuria, nephritis.

Picric acid is often used as stain and explosives. Many sites of factories that produ ce this chemical and those which use it are highly contaminated with it. Since the acid as well as its derivatives is highly sensitive in nature, it has become a matter of more concern to study the microbial degradation of this compound. Earlier, picric acid waste were disposed by means of dumping at specified land-fill areas, isolation in suitable, reinforced containers, land based deep-welling, dumping in deep water at sea and incineration. But, it is observed that other problems arise due to these methods. For example, incineration causes air pollution while land fill leads to soil contamination. If they are dumped in deep sea water , then, due to their toxic nature they affect the marine life severely. Hence, the new and only effective way of disposal of is biodegradation of the compound.

Microbial degradation of these compounds depends on the number of nitro groups on the aromatic ring. Usually, the first step in aromatic degradation is electrophilic attack. Due to the electron-withdrawing effect of the nitro group, this step becomes more difficult with an increase in the number of nitro group substituents. Consequently, very few examples of microbial metabolism of trinitroarenes have been described. In contrast to studies of 2,4,6- trinitrotoluene transformation, there have been few investigations of the metabolism of picric acid. There are only a few examples of microbial conversion of picric acid. Very few organisms that have been described previously are able to use this compound as a sole source of carbon, nitrogen, andenergy at high rates. It has been observed that if a microorganism degrades a particular aromatic compound, then it is also able to degrade other compounds of similar nature.

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