TY - JOUR
T1 - Transformation of 2, 4, 6-trinitrotoluene by Stenotrophomonas strain SG1 under aerobic and anaerobic conditions
AU - Gupta, Swati
AU - Goel, Shikhar S.
AU - Siebner, Hagar
AU - Ronen, Zeev
AU - Ramanathan, Gurunath
N1 - Funding Information:
This research was funded by the University Grant Commission (UGC) and the Israel Science Foundation (ISF) grant number 2712/17 , within the ISF-UGC Joint Research Program framework. Swati Gupta received a training fellowship from the Israel Council for Higher Education.
Publisher Copyright:
© 2022 Elsevier Ltd
PY - 2023/1/1
Y1 - 2023/1/1
N2 - TNT, or 2,4,6-trinitrotoluene, is a common explosive that can contaminate soil and groundwater in production sites, military training areas, and disposal locations. The compound is highly toxic; therefore, there is an urgent need to rehabilitate the impacted environments. Harnessing the microbial ability to biodegrade TNT into environmentally harmless compound(s) is one approach to remediating contaminated sites. In our study, we report on the genomic and metabolic ability of Stenotrophomonas strain SG1 to degrade TNT under aerobic and anaerobic conditions. The bacterial strain SG1 was first isolated as a contaminant from a culture of Diaphorobacter sp. strain DS2 over minimal media supplemented with TNT. The draft genome assembly of strain SG1 is ∼4.7 Mb and is distributed among 358 contigs. The homology search against the custom database of enzymes responsible for TNT biodegradation revealed the presence of three N-ethylmaleimide reductases (NemA) with a defined KEGG ortholog and KEGG pathway of TNT degradation. The presence of respiratory nitrate reductases has also been mapped, which supports denitrification under anaerobic conditions. Experimentally, the TNT transformation rate accelerated when carbon sources, such as sodium acetate, sodium citrate, sodium succinate, sucrose, and glucose (final concentration of 5 mM), were added. Citrate promoted the highest growth and TNT transformation ratio (88.35%) in 120 h. With the addition of 5 mM ammonium chloride, TNT completely disappeared in the citrate and sucrose-containing treatments in 120 h. However, higher biomass was obtained in the sucrose and glucose-containing treatments in 120 h. During incubation, the formation of amino dinitrotoluene isomers, dinitrotoluene isomers, trinitrobenzene, azoxy isomers, diaryl hydroxylamines, and corresponding secondary amines was confirmed by GC/MS and UPLC/MS. 2-Amino-4-nitrotoluene, 4-amino-2-nitrotoluene, and 2-amino-6-nitrotoluene were also identified in the culture supernatant by GC/MS. Under anaerobic conditions, TNT completely disappeared in the citrate and citrate plus nitrate treatments. Since the strain shows the ability to remove TNT, this research should be useful in basic research and practical applications for removing TNT from wastewater.
AB - TNT, or 2,4,6-trinitrotoluene, is a common explosive that can contaminate soil and groundwater in production sites, military training areas, and disposal locations. The compound is highly toxic; therefore, there is an urgent need to rehabilitate the impacted environments. Harnessing the microbial ability to biodegrade TNT into environmentally harmless compound(s) is one approach to remediating contaminated sites. In our study, we report on the genomic and metabolic ability of Stenotrophomonas strain SG1 to degrade TNT under aerobic and anaerobic conditions. The bacterial strain SG1 was first isolated as a contaminant from a culture of Diaphorobacter sp. strain DS2 over minimal media supplemented with TNT. The draft genome assembly of strain SG1 is ∼4.7 Mb and is distributed among 358 contigs. The homology search against the custom database of enzymes responsible for TNT biodegradation revealed the presence of three N-ethylmaleimide reductases (NemA) with a defined KEGG ortholog and KEGG pathway of TNT degradation. The presence of respiratory nitrate reductases has also been mapped, which supports denitrification under anaerobic conditions. Experimentally, the TNT transformation rate accelerated when carbon sources, such as sodium acetate, sodium citrate, sodium succinate, sucrose, and glucose (final concentration of 5 mM), were added. Citrate promoted the highest growth and TNT transformation ratio (88.35%) in 120 h. With the addition of 5 mM ammonium chloride, TNT completely disappeared in the citrate and sucrose-containing treatments in 120 h. However, higher biomass was obtained in the sucrose and glucose-containing treatments in 120 h. During incubation, the formation of amino dinitrotoluene isomers, dinitrotoluene isomers, trinitrobenzene, azoxy isomers, diaryl hydroxylamines, and corresponding secondary amines was confirmed by GC/MS and UPLC/MS. 2-Amino-4-nitrotoluene, 4-amino-2-nitrotoluene, and 2-amino-6-nitrotoluene were also identified in the culture supernatant by GC/MS. Under anaerobic conditions, TNT completely disappeared in the citrate and citrate plus nitrate treatments. Since the strain shows the ability to remove TNT, this research should be useful in basic research and practical applications for removing TNT from wastewater.
KW - Aerobic
KW - Explosives
KW - Reduction pathway
KW - Stenotrophomonas
KW - TNT transformation
UR - http://www.scopus.com/inward/record.url?scp=85141272280&partnerID=8YFLogxK
U2 - 10.1016/j.chemosphere.2022.137085
DO - 10.1016/j.chemosphere.2022.137085
M3 - Article
C2 - 36328316
AN - SCOPUS:85141272280
VL - 311
JO - Chemosphere
JF - Chemosphere
SN - 0045-6535
M1 - 137085
ER -
