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Studies on the biodegradation of nitroaromatic pollutants by the isolated bacterial cultures

Shodhganga@INFLIBNET

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Title Studies on the biodegradation of nitroaromatic pollutants by the isolated bacterial cultures
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Contributor Ninnekar, H Z
 
Subject Biochemistry
nitroaromatic pollutants
 
Description Nitroaromatic compounds are the major chemical pollutants because of their widespread use and toxicity. Nitrotoluenes, nitrobenzoates, nitrophenols, nitrobenzene and nitroanilines are extensively used in industry for manufacture of pesticides, explosives, dyes, plastics and pharmaceuticals. Many of these chemicals are reported to be either toxic, mutagenic or carcinogenic to humans and animals. Microorganisms play a vital role in the detoxification of such hazardous chemicals through the process of biodegradation. Hence, the present investigation has been undertaken to isolate and characterize indigenous microorganisms capable of degrading nitroaromatic pollutants and to study their biodegradative pathways. A bacterial consortium capable of degrading nitroaromatic compounds was isolated from pesticide-contaminated agricultural soil samples by selective enrichment on 2-nitrotoluene as a sole source of carbon and energy. The three different bacterial isolates obtained from bacterial consortium were identified as Bacillus sp., Bacillus flexus and Micrococcus sp. on the basis of their morphological and biochemical characteristics and by the phylogenetic analysis based on 16S rRNA gene sequences. The bacterial isolates utilized various nitroaromatic compounds as growth substrates. The pathways for the degradation of 2-nitrotoluene by Micrococcus sp. strain SMN-1 and 3-nitrobenzoic acid by Bacillus flexus strain XJU-4 were elucidated by the isolation and identification of metabolites, growth and enzymatic studies. Micrococcus sp. strain SMN-1 degraded 2-nitrotoluene to 3-methylcatechol with release of nitrite. The cell-free extract of Micrococcus sp. strain SMN-1 grown on 2-nitrotoluene contained the activity of catechol 2,3-dioxygenase, which suggest that 3-methylcatechol was further degraded by a metacleavage pathway. Bacillus flexus strain XJU-4 degraded 3-nitrobenzoic acid to protocatechuic acid with release of nitrite. The cell-free extract of Bacillus flexus strain XJU-4 grown on 3-nitrobenzoic acid
Bibliography p.177-217
 
Date 2013-05-13T12:53:28Z
2013-05-13T12:53:28Z
2013-05-13
n.d.
2011
n.d.
 
Type Ph.D.
 
Identifier http://hdl.handle.net/10603/8744
 
Language English
 
Relation -
 
Rights university
 
Format 217p.
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None
 
Coverage Biochemistry
 
Publisher Dharwad
Karnatak University
Department of Bio-Chemistry
 
Source INFLIBNET