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Novel pathway for the degradation of 2-chloro-4-nitrobenzoic acid by Acinetobacter sp. strain RKJ12.

DIR@IMTECH: CSIR-Institute of Microbial Technology

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Title Novel pathway for the degradation of 2-chloro-4-nitrobenzoic acid by Acinetobacter sp. strain RKJ12.
 
Creator Prakash, Dhan
Kumar, Ravi
Jain, R K
Tiwary, B N
 
Subject QR Microbiology
 
Description The organism Acinetobacter sp. RKJ12 is capable of utilizing 2-chloro-4-nitrobenzoic acid (2C4NBA) as a sole source of carbon, nitrogen, and energy. In the degradation of 2C4NBA by strain RKJ12, various metabolites were isolated and identified by a combination of chromatographic, spectroscopic, and enzymatic activities, revealing a novel assimilation pathway involving both oxidative and reductive catabolic mechanisms. The metabolism of 2C4NBA was initiated by oxidative ortho dehalogenation, leading to the formation of 2-hydroxy-4-nitrobenzoic acid (2H4NBA), which subsequently was metabolized into 2,4-dihydroxybenzoic acid (2,4-DHBA) by a mono-oxygenase with the concomitant release of chloride and nitrite ions. Stoichiometric analysis indicated the consumption of 1 mol O(2) per conversion of 2C4NBA to 2,4-DHBA, ruling out the possibility of two oxidative reactions. Experiments with labeled H(2)(18)O and (18)O(2) indicated the involvement of mono-oxygenase-catalyzed initial hydrolytic dechlorination and oxidative denitration mechanisms. The further degradation of 2,4-DHBA then proceeds via reductive dehydroxylation involving the formation of salicylic acid. In the lower pathway, the organism transformed salicylic acid into catechol, which was mineralized by the ortho ring cleavage catechol-1,2-dioxygenase to cis, cis-muconic acid, ultimately forming tricarboxylic acid cycle intermediates. Furthermore, the studies carried out on a 2C4NBA(-) derivative and a 2C4NBA(+) transconjugant demonstrated that the catabolic genes for the 2C4NBA degradation pathway possibly reside on the ∼55-kb transmissible plasmid present in RKJ12.
 
Publisher ASM
 
Date 2011-09
 
Type Article
PeerReviewed
 
Format application/pdf
 
Identifier http://crdd.osdd.net/open/455/1/dhanprakash11.pdf
Prakash, Dhan and Kumar, Ravi and Jain, R K and Tiwary, B N (2011) Novel pathway for the degradation of 2-chloro-4-nitrobenzoic acid by Acinetobacter sp. strain RKJ12. Applied and environmental microbiology, 77 (18). pp. 6606-13. ISSN 1098-5336
 
Relation http://aem.asm.org/content/77/18/6606.full.pdf+html
http://crdd.osdd.net/open/455/