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Aamir Khan M, Sharma A, Yadav S, Celin SM, Sharma S. A sketch of microbiological remediation of explosives-contaminated soil focused on state of art and the impact of technological advancement on hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) degradation. CHEMOSPHERE 2022; 294:133641. [PMID: 35077733 DOI: 10.1016/j.chemosphere.2022.133641] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 01/02/2022] [Accepted: 01/13/2022] [Indexed: 06/14/2023]
Abstract
When high-energy explosives such as hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), 2,4,6-trinitrotoluene (TNT) are discharged into the surrounding soil and water during production, testing, open dumping, military, or civil activities, they leave a toxic footprint. The US Environmental Protection Agency has labeled RDX as a potential human carcinogen that must be degraded from contaminated sites quickly. Bioremediation of RDX is an exciting prospect that has received much attention in recent years. However, a lack of understanding of RDX biodegradation and the limitations of current approaches have hampered the widespread use of biodegradation-based strategies for RDX remediation at contamination sites. Consequently, new bioremediation technologies are required to enhance performance. In this review, we explore the requirements for in-silico analysis for producing biological models of microbial remediation of RDX in soil. On the other hand, potential gene editing methods for getting the host with target gene sequences responsible for the breakdown of RDX are also reported. Microbial formulations and biosensors for detection and bioremediation are also briefly described. The biodegradation of RDX offers an alternative remediation method that is both cost-effective and ecologically acceptable. It has the potential to be used in conjunction with other cutting-edge technologies to further increase the efficiency of RDX degradation.
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Affiliation(s)
- Mohd Aamir Khan
- Centre for Rural Development & Technology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016, India
| | - Abhishek Sharma
- Amity Food and Agriculture Foundation, Amity University Uttar Pradesh, Noida, 201313, India.
| | - Sonal Yadav
- Centre for Rural Development & Technology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016, India
| | - S Mary Celin
- Centre for Fire, Explosives and Environment Safety, Defence Research & Development Organization, Brig. Mazumdar Road, Delhi, 110 054, India
| | - Satyawati Sharma
- Centre for Rural Development & Technology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016, India
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Li J, Yang X, Lai JL, Zhang Y, Luo XG, Zhao SP, Zhu YB. Characteristics of RDX degradation and the mechanism of the RDX exposure response in a Klebsiella sp. strain. Biochem Eng J 2021. [DOI: 10.1016/j.bej.2021.108174] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Yang X, Zhang Y, Lai JL, Luo XG, Han MW, Zhao SP, Zhu YB. Analysis of the biodegradation and phytotoxicity mechanism of TNT, RDX, HMX in alfalfa (Medicago sativa). CHEMOSPHERE 2021; 281:130842. [PMID: 34023765 DOI: 10.1016/j.chemosphere.2021.130842] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 04/26/2021] [Accepted: 05/05/2021] [Indexed: 06/12/2023]
Abstract
The aim of this study was to reveal the mechanism underlying the toxicity of TNT (trinitrotoluene), RDX (cyclotrimethylene trinitroamine), and HMX (cyclotetramethylene tetranitramine) explosives pollution in plants. Here, the effects of exposure to these three explosives were examined on chlorophyll fluorescence, antioxidant enzyme activity, and the metabolite spectrum in alfalfa (Medicago sativa) plants. The degradation rates for TNT, RDX, and HMX by alfalfa were 26.8%, 20.4%, and 18.4%, respectively, under hydroponic conditions. TNT caused damage to the microstructure of the plant roots and inhibited photosynthesis, whereas RDX and HMX induced only minor changes. Exposure to any of the three explosives caused disturbances in the oxidase system. Non-targeted metabolomics identified a total of 6185 metabolites. TNT exposure induced the appearance of 609 differentially expressed metabolites (189 upregulated, 420 downregulated), RDX exposure induced 197 differentially expressed metabolites (155 upregulated and 42 downregulated), and HMX induced 234 differentially expressed metabolites (132 upregulated and 102 downregulated). Of these differentially expressed metabolites, lipids and lipid-like molecules were the main metabolites induced by explosives poisoning. TNT mainly caused significant changes in the alanine, aspartate, and glutamate metabolism metabolic pathways, RDX mainly caused disorders in the arginine biosynthesis metabolic pathway, and HMX disrupted the oxidative phosphorylation metabolic pathway. Taken together, the results show that exposure to TNT, RDX, and HMX leads to imbalances in plant photosynthetic characteristics and antioxidant enzyme systems, changes the basic metabolism of plants, and has significant ecotoxicity effects.
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Affiliation(s)
- Xu Yang
- School of Life Science and Engineering, Southwest University of Science and Technology, Mianyang, 621010, China
| | - Yu Zhang
- School of Life Science and Engineering, Southwest University of Science and Technology, Mianyang, 621010, China
| | - Jin-Long Lai
- School of Life Science and Engineering, Southwest University of Science and Technology, Mianyang, 621010, China; Engineering Research Center of Biomass Materials, Ministry of Education of, SWUST, Mianyang, 621010, China.
| | - Xue-Gang Luo
- School of Life Science and Engineering, Southwest University of Science and Technology, Mianyang, 621010, China; Engineering Research Center of Biomass Materials, Ministry of Education of, SWUST, Mianyang, 621010, China
| | - Meng-Wei Han
- State Key Laboratory of NBC Protection for Civilian, Beijing, 102205, China
| | - San-Ping Zhao
- State Key Laboratory of NBC Protection for Civilian, Beijing, 102205, China.
| | - Yong-Bing Zhu
- State Key Laboratory of NBC Protection for Civilian, Beijing, 102205, China
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Dang H, Cupples AM. Diversity and abundance of the functional genes and bacteria associated with RDX degradation at a contaminated site pre- and post-biostimulation. Appl Microbiol Biotechnol 2021; 105:6463-6475. [PMID: 34357428 DOI: 10.1007/s00253-021-11457-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 06/30/2021] [Accepted: 07/03/2021] [Indexed: 11/28/2022]
Abstract
Bioremediation is becoming an increasingly popular approach for the remediation of sites contaminated with the explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). Multiple lines of evidence are often needed to assess the success of such approaches, with molecular studies frequently providing important information on the abundance of key biodegrading species. Towards this goal, the current study utilized shotgun sequencing to determine the abundance and diversity of functional genes (xenA, xenB, xplA, diaA, pnrB, nfsI) and species previously associated with RDX biodegradation in groundwater before and after biostimulation at an RDX-contaminated Navy Site. For this, DNA was extracted from four and seven groundwater wells pre- and post-biostimulation, respectively. From a set of 65 previously identified RDX degraders, 31 were found within the groundwater samples, with the most abundant species being Variovorax sp. JS1663, Pseudomonas fluorescens, Pseudomonas putida, and Stenotrophomonas maltophilia. Further, 9 RDX-degrading species significantly (p<0.05) increased in abundance following biostimulation. Both the sequencing data and qPCR indicated that xenA and xenB exhibited the highest relative abundance among the six genes. Several genes (diaA, nsfI, xenA, and pnrB) exhibited higher relative abundance values in some wells following biostimulation. The study provides a comprehensive approach for assessing biomarkers during RDX bioremediation and provides evidence that biostimulation generated a positive impact on a set of key species and genes. KEY POINTS: • A co-occurrence network indicated diverse RDX degraders. • >30 RDX-degrading species were detected. • Nine RDX-degrading species increased following biostimulation. • Sequencing and high-throughput qPCR indicated that xenA and xenB were most abundant.
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Affiliation(s)
- Hongyu Dang
- Department of Civil and Environmental Engineering, Michigan State University, A135, 1449 Engineering Research Court, East Lansing, Michigan, 48824, USA
| | - Alison M Cupples
- Department of Civil and Environmental Engineering, Michigan State University, A135, 1449 Engineering Research Court, East Lansing, Michigan, 48824, USA.
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Niedźwiecka JB, McGee K, Finneran KT. Combined Biotic-Abiotic 2,4-Dinitroanisole Degradation in the Presence of Hexahydro-1,3,5-trinitro-1,3,5-triazine. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:10638-10645. [PMID: 32687325 DOI: 10.1021/acs.est.0c02363] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The Department of Defense has developed new explosive formulations in which traditionally used cyclic nitramines such as hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) have been updated with the insensitive munition (IM) 2,4-dinitroanisole (DNAN). Understanding combined degradation of both compounds at explosive-contaminated sites will allow remediation approaches that simultaneously target both contaminants. DNAN reduction in the presence of RDX was evaluated in abiotic experiments using substoichiometric, stoichiometric, and superstoichiometric concentrations of ferrous iron and anthrahydroquinone disulfonate within a pH range from 7.0 to 9.0. Biological degradation was investigated in resting cell suspensions of Geobacter metallireducens strain GS-15, a model Fe(III)-reducing Bacteria. Cells were amended into anoxic tubes buffered at pH 7.0, with initial 100 μM DNAN and 40-50 μM RDX. In both abiotic and biological experiments, the DNAN was reduced through the intermediate 2-methoxy-5-nitroaniline or 4-methoxy-3-nitroaniline to 2,4-diaminoanisole. In biological experiments, the RDX was reduced to form methylenedinitramine, formaldehyde (HCHO), and ammonium (NH4+). Cells were able to reduce both DNAN and RDX most readily in the presence of extracellular electron shuttles and/or Fe(III). DNAN degradation (abiotic and biotic) was faster than degradation of RDX, suggesting that the reduction of IMs will not be inhibited by cyclic nitramines, but degradation dynamics did change in mixtures when compared to singular compounds.
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Affiliation(s)
- Jolanta B Niedźwiecka
- Environmental Engineering and Earth Sciences, Clemson University, 312 Biosystems Research Complex (BRC) Suite 312, Clemson, South Carolina 29634, United States
- Department of Ecosystem Biology, Faculty of Science, University of South Bohemia, Branišovská 1760, České Budějovice 370 05, Czech Republic
| | - Kameryn McGee
- Environmental Engineering and Earth Sciences, Clemson University, 312 Biosystems Research Complex (BRC) Suite 312, Clemson, South Carolina 29634, United States
| | - Kevin T Finneran
- Environmental Engineering and Earth Sciences, Clemson University, 312 Biosystems Research Complex (BRC) Suite 312, Clemson, South Carolina 29634, United States
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