Abatement of Pollution through Genetically Engineered Microorganisms
For detoxification and degradation of toxic chemicals, enzymes are encoded by specific genes present on plasmids. Chakraborty and coworkers (1979) succeeded in isolating the microbial culture which could utilize a number of organic chemicals, toxic in nature, such as salicylate, 2,4-D, 3 chlorobenzenes, ethylene, biphenyls, 1,2,4-trimethylbenzene, 2, 4, 5-trichlorophenoxy-acetic acid, etc.
(Chatterjee et al,
1981; Kellogg et al.,
Fig. 5.12. Creation of a superbug (Diagrammatic).
Genes responsible for degradation of environmental pollutants, for example, toluene, chlorobenzene acids, and other halogenated pesticides and toxic wastes have been identified. For every compound, one separate plasmid is required. It is not like that one plasmid can degrade all the toxic compounds of different groups. The plasmids are grouped into four categories:
||OCT plasmid which degrades, octane, hexane and decane,
||XYL plasmid which degrades xylene and toluenes,
||CAM plasmid that decompose camphor, and
||NAH plasmid which degrades naphthalene.
Dr Anand Mohan Chakrabarty (an Indian borne American scientist) produced a new product of genetic engineering called as superbug (oil eating bug) by introducing plasmids from different strains into a single cell of P. putida.
This superbug is such that can degrade all the four types of substrates for which four separate plasmids were required (Fig 5.12).
The plasmids of P. putida
degrading various chemical compounds are TOL (for toluene and xylene), RA500 (for 3,5-xylene) pAC 25 (for 3-cne chlorobenxoate), pKF439 (for salicylatetoluene). Plasmid WWO of P. putida
is one member of a set of plasmids now termed as TOL plasmid. WWO is propagated in E. coli
(Chatterjee et al,
1981; Kellogg et al
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