Biotransformation of 2, 4, 6, 8, 10, 12-hexanitro-2, 4, 6, 8, 10, 12-hexaazaisowurtzitane (CL-20) by a denitrifying Pseudomonas sp. FA 1

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DOIResolve DOI: http://doi.org/10.1128/AEM.69.9.5216-5221.2003
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TypeArticle
Journal titleApplied and Environmental Microbiology
Volume69
Issue9
Pages52165221; # of pages: 6
Subjectenv
AbstractThe microbial and enzymatic degradation of a new energetic compound, 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20), is not well understood. Fundamental knowledge about the mechanism of microbial degradation of CL-20 is essential to allow the prediction of its fate in the environment. In the present study, a CL-20-degrading denitrifying strain capable of utilizing CL-20 as the sole nitrogen source, Pseudomonas sp. strain FA1, was isolated from a garden soil. Studies with intact cells showed that aerobic conditions were required for bacterial growth and that anaerobic conditions enhanced CL-20 biotransformation. An enzyme(s) involved in the initial biotransformation of CL-20 was shown to be membrane associated and NADH dependent, and its expression was up-regulated about 2.2-fold in CL-20-induced cells. The rates of CL-20 biotransformation by the resting cells and the membrane-enzyme preparation were 3.2+-0.1 nmol h-1 mg of cell biomass-1 and 11.5+-0.14 nmol h-1 mg of protein-1, respectively, under anaerobic conditions. In the membrane-enzyme-catalyzed reactions, 2.3 nitrite ions (NO2-), 1.5 molecules of nitrous oxide (N2O), and 1.7 molecules of formic acid (HCOOH) were produced per reacted CL-20 molecule. The membrane-enzyme preparation reduced nitrite to nitrous oxide under anaerobic conditions. A comparative study of native enzymes, deflavoenzymes, and a reconstituted enzyme(s) and their subsequent inhibition by diphenyliodonium revealed that biotransformation of CL-20 is catalyzed by a membrane-associated flavoenzyme. The latter catalyzed an oxygen-sensitive one-electron transfer reaction that caused initial N denitration of CL-20.
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AffiliationNational Research Council Canada; NRC Biotechnology Research Institute
Peer reviewedNo
NRC number45949
NPARC number3538908
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Record identifierdb85d011-7126-48f0-a241-7719e35fedbe
Record created2009-03-01
Record modified2016-05-09
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