Genetically engineered microorganisms for the detection of explosives' residues

Abstract

The manufacture and use of explosives throughout the past century has resulted in the extensive pollution of soils and groundwater, and the widespread interment of landmines imposes a major humanitarian risk and prevents civil development of large areas. As most current landmine detection technologies require actual presence at the surveyed areas, thus posing a significant risk to personnel, diverse research efforts are aimed at the development of remote detection solutions. One possible means proposed to fulfill this objective is the use of microbial bioreporters: genetically engineered microorganisms "tailored" to generate an optical signal in the presence of explosives' vapors. The use of such sensor bacteria will allow to pinpoint the locations of explosive devices in a minefield. While no study has yet resulted in a commercially operational system, significant progress has been made in the design and construction of explosives-sensing bacterial strains. In this article we review the attempts to construct microbial bioreporters for the detection of explosives, and analyze the steps that need to be undertaken for this strategy to be applicable for landmine detection.

Keywords: 2,4,6- trinitrotoluene; 2,4-dinitrotoluene; bioluminescence; biosensors; explosives; landmines; microbial bioreporters.

FIGURE 1

Schematic description of a “lights on” bioreporter design. A target analyte molecule enters the cell. The analyte, or its metabolite, is identified by a regulatory protein, which then activates the promoter attached to the reporter gene. Transcription is initiated, resulting in the synthesis of a reporter protein and the production of a measurable signal.

FIGURE 2

(A,B) yqjF-based bioreporter response when immobilized in agar and exposed to DNT buried in soil; (A) bioluminescent lux-based reporter; (B) fluorescent gfp-based reportet (from Yagur-Kroll et al., 2014, by permission; copyright (2013) Springer-Verlag Berlin Heidelberg). (C) yqjF-based bioluminescent bioreporter response when spread on LB agar plates and exposed to disks soaked with varying amounts of DNT (Yagur-Kroll et al., unpublished). (D) xylR5-based bioreporter response to DNT vapors and DNT crystals (from Garmendia et al., 2008, by permission). (E) xylR5-based bioreporter fluorescent response when spread on LB agar plates supplemented with DNT (from Garmendia et al., 2008, by permission; copyright (2008) Society for Applied Microbiology and Blackwell Publishing Ltd.). (F) Riboswitch-based bioreporer response to DNT when riboswitch is in “ON” or “OFF” mode at time zero and after 4 h of exposure. Reprinted (adapted) with permission from Davidson et al. (2012). Copyright (2012) American Chemical Society.