Authors: SongHua Zhu Jens Reuther Jie Liu Fiona H Crocker Karl J Indest Lindsay D Eltis William W Mohn
Publish Date: 2014/08/22
Volume: 99, Issue: 1, Pages: 459-467
Abstract
Hexahydro135trinitro135triazine RDX is a widely used explosive and a major soil and groundwater contaminant Organisms such as Gordonia sp KTR9 capable of degrading RDX and using it as an N source may prove useful for bioremediation of contaminated sites XplA is a cytochrome P450 monooxygenase responsible for RDX degradation Expression of xplA in KTR9 was not induced by RDX but was strongly induced 50fold during Nlimited growth When glnR encoding a regulatory protein affecting N assimilation in diverse Actinobacteria was deleted from KTR9 the bacterium lost the ability to use nitrate nitrite and RDX as N sources Deletion of glnR also abolished the inhibition of xplA expression by nitrite Our results confirm the essential role of GlnR in regulating assimilation of nitrite but there was no evidence for a direct role of GlnR in regulating XplA expression Rather the general availability of nitrogen repressed XplA expression We conclude that the inability of the glnR mutant to use RDX as an N source was due to its inability to assimilate nitrite an intermediate in the assimilation of nitrogen from RDX Regulation of XplA does not seem adaptive for KTR9 but it is important for RDX bioremediation with KTR9 or similar bacteriaThis research was funded in part through grants from Genome BC the Strategic Environmental Research and Development Program Project ER1609 and the US Army Corps of Engineers Environmental Quality Program Views opinions and/or findings contained herein are those of the authors and should not be construed as an official Department of the Army position or decision unless so designated by other official documentation We thank Christine Florizone for guidance in chemical analyses
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