Study on aerobic degradation of 2,4,6-trinitrotoluene (TNT) using Pseudarthrobacter chlorophenolicus collected from the contaminated site

High-proportions of tailwater discharge alter microbial community composition and assembly in receiving sediments

The tailwater from wastewater treatment plants serves as an important water resource in arid regions, alleviating the conflict between supply and demand. However, the effects of different tailwater discharge proportions on microbial community dynamics remain unclear. In this study, we investigated the effects of different tailwater discharge proportions on the water quality and microbial community characteristics of sediments in receiving water bodies under controlled conditions (WF-1, WF-2, WF-3, WF-4, and WF-5, containing 0% tailwater + 100% natural water, 25% tailwater + 75% natural water, 50% tailwater + 50% natural water, 75% tailwater + 25% natural water, and 100% tailwater + 0% natural water, respectively). Microbial co-occurrence networks and structural equation model were used to unveil the relationship between microbial communities and their shaping factors. Results showed that distinct microbial community compositions were found in the sediments with low- (< 50%) and high- (> 50%) proportions of tailwater. Specifically, WCHB1-41 and g_4-29-1, which are involved in organic degradation-related functions, were the key genera in the high-proportion cluster. A total of 21 taxa were more abundant in the low-proportion (< 50%) cluster than that in high-proportion (> 50%). Moreover, higher modularity was observed in the low-proportion. Total phosphorus directly affected while ammonia nitrogen indirectly affected the microbial community structure. Our findings support the distinct heterogeneity of microbial communities driven by tailwater discharge in receiving water bodies, and further confirmed that high-proportion tailwater depletes sensitive microbial communities, which may be avoided through scientific management.

Microecological characteristics of water bodies/sediments and microbial remediation strategies after 50 years of pollution exposure in ammunition destruction sites in China

The effects of long-term ammunition pollution on microecological characteristics were analyzed to formulate microbial remediation strategies. Specifically, the response of enzyme systems, N/O stable isotopes, ion networks, and microbial community structure/function levels were analyzed in long-term (50 years) ammunition-contaminated water/sediments from a contamination site, and a compound bacterial agent capable of efficiently degrading trinitrotoluene (TNT) while tolerating many heavy metals was selected to remediate the ammunition-contaminated soil. The basic physical and chemical properties of the water/sediment (pH (up: 0.57-0.64), nitrate (up: 1.31-4.28 times), nitrite (up: 1.51-5.03 times), and ammonium (up: 7.06-70.93 times)) were changed significantly, and the significant differences in stable isotope ratios of N and O (nitrate nitrogen) confirmed the degradability of TNT by indigenous microorganisms exposed to long-term pollution. Heavy metals, such as Pb, Zn, Cu, Cd, Cs, and Sb, have synergistic toxic effects in ammunition-contaminated sites, and significantly decreased the microbial diversity and richness in the core pollution area. However, long-term exposure in the edge pollution area induced microorganisms to use TNT as a carbon and nitrogen sources for life activities and growth and development. The Bacteroidales microbial group was significantly inhibited by ammunition contamination, whereas microorganisms such as Proteobacteria, Acidobacteriota, and Comamonadaceae gradually adapted to this environmental stress by regulating their development and stress responses. Ammunition pollution significantly affected DNA replication and gene regulation in the microecological genetic networks and increased the risk to human health. Mg and K were significantly involved in the internal mechanism of microbial transport, enrichment, and metabolism of TNT. Nine strains of TNT-utilizing microbes were screened for efficient TNT degradation and tolerance to typical heavy metals (copper, zinc and lead) found in contaminated sites, and a compound bacterial agent prepared for effective repair of ammunition-contaminated soil significantly improved the soil ecological environment.

Efficient removal of 2,4,6-trinitrotoluene (TNT) from industrial/military wastewater using anodic oxidation on boron-doped diamond electrodes

With growing public concern about water quality particular focus should be placed on organic micropollutants, which are harmful to the environment and people. Hence, the objective of this research is to enhance the security and resilience of water resources by developing an efficient system for reclaiming industrial/military wastewater and protecting recipients from the toxic and cancerogenic explosive compound-2,4,6-trinitrotoluene (TNT), which has been widely distributed in the environment. This research used an anodic oxidation (AO) process on a boron-doped diamond (BDD) electrode for the TNT removal from artificial and real-life matrices: marine water and treated wastewater. During experiments, TNT concentrations were significantly decreased, reaching the anodic degradation efficiency of above 92% within two hours and > 99.9% after six hours of environmental sample treatment. The presented results show the great potential of AO performed on BDD anodes for full-scale application in the industry and military sectors for TNT removal.

Isolation and characterization of nitroguanidine-degrading microorganisms

Nitroguanidine (NQ) is a component of newly developed insensitive munition (IM) formulations which are more resistant to impact, friction, heat, or sparks than conventional explosives. NQ is also used to synthesize various organic compounds and herbicides, and has both human and environmental health impacts. Despite the wide application and associated health concerns, limited information is known regarding NQ biodegradation, and only one NQ-degrading pure culture identified as Variovorax strain VC1 has been characterized. Here, we present results for three new NQ-degrading bacterial strains isolated from soil, sediment, and a lab-scale aerobic membrane bioreactor (MBR), respectively. Each of these strains -utilizes NQ as a nitrogen (N) source rather than as a source of carbon or energy. The MBR strain, identified as Pseudomonas extremaustralis strain NQ5, is capable of degrading NQ at a rate of approximately 150 μmole L-1 h-1 under aerobic conditions with glucose as a sole carbon source - and NQ as a sole N source. The addition of NH4+ to strain NQ5 during active growth with NQ as a sole N source slowed the growth rate for several hours, and the strain released NH4+, presumably from NQ. When NO3- was added as an alternate N source under similar conditions, the NO3- was not consumed, but NH4+ release into the culture medium was again observed. Strain NQ5 was also able to utilize guanylurea, guanidine, and ethyl allophanate as N sources, and - tolerate salt concentrations as high as 4 % (as NaCl). The other two stains, NQ4 and NQ7, both identified as Arthrobacter spp., grew significantly slower than strain NQ5 under similar culture conditions and tolerated only ∼1 % NaCl. In addition, neither strain NQ4 nor strain NQ7 was able to degrade guanlyurea or ethyl allophanate, but each degraded guanidine. These strains, particularly strain NQ5, may have practical applications for in-situ and ex-situ NQ bioremediation.

Isolation and characterization of the aspartame-degrading strain Pseudarthrobacter sp. AS-1

Aspartame is one of the main varieties of artificial sweeteners. Although it has been approved as a food additive, the environmental hazards and ecological risks posed by aspartame are attracting more and more attention. In the present study, strain Pseudarthrobacter sp. AS-1 was isolated and characterized as an efficient aspartame degrader. Strain AS-1 was capable of degrading 200 mg L-1 aspartame within 10 h under conditions optimized at 30 °C and pH 8.0. At the same time, it was found that enzymes degrading aspartame in strain AS-1 were induced and secreted extracellularly. Degradation of aspartame in Pseudarthrobacter sp. AS-1 was identified as following: it was first demethylated to aspartyl-phenylalanine, then degraded to phenylalanine and aspartate, and finally the two amino acids were further degraded. In addition, strain AS-1 was able to remove more than 85% of aspartame in soil and river water. It is the first time that pure bacterial cultures were reported to have the capability of aspartame degradation. These findings add to our knowledge of the microbial metabolic mechanisms of aspartame.

Biotransformation of 2,4,6-trinitrotoluene by Diaphorobacter sp. strain DS2

Diaphorobacter strain DS2 degrades 3-nitrotoluene and 2-nitrotoluene via ring oxidation with 3-nitrotoluene dioxygenase (3NTDO). In the current study, we hypothesized that 3NTDO might also be involved in the degradation of 2,4,6-trinitrotoluene (TNT), a major nitroaromatic explosive contaminant in soil and groundwater. Strain DS2 transforms TNT as a sole carbon and nitrogen source when grown on it. Ammonium chloride and succinate in the medium accelerated the TNT degradation rate. A resting cell experiment suggested that TNT does not compete with 3NT degradation (no negative impact of TNT on the reaction velocity for 3NT). Enzyme assay with 3NTDO did not exhibit TNT transformation activity. The above results confirmed that 3NTDO of DS2 is not responsible for TNT degradation. In the resting cell experiment, within 10 h, 4ADNT completely degraded. The degradation of 2ADNT was 97% at the same time. We hypothesized that 3NTDO involve in this reaction. Based on the DS2 genome, we proposed that the N-ethylmaleimide reductases (nemA) were involved in the initial reduction of the nitro group and aromatic ring of TNT. Our findings suggest that strain DS2 could be helpful for the removal of TNT from contaminated sites with or without any additional carbon and nitrogen source and with minimal accumulation of undesirable intermediates.

Oxygen-insensitive nitroreductase bacteria-mediated degradation of TNT and proteomic analysis

2,4,6-trinitrotoluene (TNT) is a nitroaromatic compound that causes soil and groundwater pollution during manufacture, transportation, and use, posing significant environmental and safety hazards. In this study, a TNT-degrading strain, Bacillus cereus strain T4, was screened and isolated from TNT-contaminated soil to explore its degradation characteristics and proteomic response to TNT. The results showed that after inoculation with the bacteria for 4 h, the TNT degradation rate reached 100% and was transformed into 2-amino-4,6-dinitrotoluene (2-ADNT), 4-amino-2,6-dinitrotoluene (4-ADNT), 2,4-diamino-6-nitrotoluene (2,4-DANT), and 2,6-diamino-4-nitrotoluene (2,6-DANT), accompanied by the accumulation of nitrite and ammonium ions. Through proteomic sequencing, we identified 999 differentially expressed proteins (482 upregulated, 517 downregulated), mainly enriched in the pentose phosphate, glycolysis/gluconeogenesis, and amino acid metabolism pathways. In addition, the significant upregulation of nitroreductase and N-ethylmaleimide reductase was closely related to TNT denitration and confirmed that the strain T4 converted TNT into intermediate metabolites such as 2-ADNT and 4-ADNT. Therefore, Bacillus cereus strain T4 has the potential to degrade TNT and has a high tolerance to intermediate products, which may effectively degrade nitroaromatic pollutants such as TNT in situ remediation in combination with other bacterial communities.

Compost with spent mushroom substrate and chicken manure enhances rice seedling quality and reduces soil-borne pathogens

Using cultivated soils for rice seedlings can reduce the sustainability of arable land and thus giving negative impacts to food production. As a substitute, spent mushroom compost (SMC), which has high water-holding capacity and nutrient content, shows great potentials. To determine the impacts of the proportion of SMC and paddy soil on seedling quality, rhizosphere microbial characteristics, and fungal pathogens in rice seedling substrates, we conducted a 21-day pot experiment for rice seedling under five treatments: CK, 100% paddy soil; R1, 20% SMC and 80% paddy soil; R2, 50% SMC and 50% paddy soil; R3, 80% SMC and 20% paddy soil; and R4, 100% SMC. The results showed that incorporating SMC into the substrate, especially at 50% volume (R2), increased seedling growth and vitality at the seedling growth stage without external fertilization. Moreover, the SMC amendment increased microbial activity and promoted rice seedling recruitment of plant growth-promoting rhizobacteria (PGPR) and fungi (PGPF). In addition, using SMC significantly reduced the abundance of pathogenic fungi, especially Magnaporthe grisea. Overall, the multi-faceted benefits exhibit the strong possibilities of using SMC in sustainable rice productions.

Pseudarthrobacter humi sp. nov., an actinobacterium isolated from soil

A Gram-stain-positive, facultatively aerobic, rod-shaped and non-motile bacterial strain designated RMG13^T was isolated from the soil near Gaetgol Eco Park and collected in Siheung-si, Republic of Korea. It was taxonomically characterized through polyphasic analysis. Phylogenetic analysis based on the 16S rRNA gene revealed that the novel isolate was most closely related to the type strains of species of the genus Pseudarthrobacter. RMG13^T shared the highest similarities with Pseudarthrobacter sulfonivorans ALL^T (99.2 %) and Pseudarthrobacter psychrotolerans YJ56^T (99.0 %). In silico DNA-DNA hybridization values of RMG13^T with P. sulfonivorans ALL^T and P. psychrotolerans YJ56^T were 28.1 and 41.8 %, respectively. The average nucleotide identities of RMG13^T with P. sulfonivorans ALL^T and P. psychrotolerans YJ56^T were 84.2 and 70.3 %, respectively, whilst the average amino acid identities of RMG13^T with P. sulfonivorans ALL^T and P. psychrotolerans YJ56^T were 90.5 and 74.6 %, respectively. Two-dimensional thin-layer chromatography showed that the major polar lipids of RMG13^T were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylinositol, and its major cellular fatty acids were anteiso-C_15 : 0, iso-C_15 : 0 and anteiso-C_17 : 0. MK-9 (H2) was the sole menaquinone. Cells grew at 4-37 °C (optimum 30 °C) and pH 5.0-12.0 (optimum pH 8.0) in Reasoner's 2A (MB cell). The cells tolerated 0-5% NaCl (w/v) but not 6 % NaCl. The DNA G+C content of RMG13^T was 65.0 %. The results of phenotypic, genotypic, chemotaxonomic and phylogenetic analyses indicated that RMG13^T represents a novel member of the genus Pseudarthrobacter, and the proposed name is P. humi sp. nov. The type strain of P. humi is RMG13^T (= KACC 22359^T = TBRC 15115^T).

Comparative Genomic Analysis of Antarctic Pseudomonas Isolates with 2,4,6-Trinitrotoluene Transformation Capabilities Reveals Their Unique Features for Xenobiotics Degradation

The nitroaromatic explosive 2,4,6-trinitrotoluene (TNT) is a highly toxic and persistent environmental pollutant. Since physicochemical methods for remediation are poorly effective, the use of microorganisms has gained interest as an alternative to restore TNT-contaminated sites. We previously demonstrated the high TNT-transforming capability of three novel Pseudomonas spp. isolated from Deception Island, Antarctica, which exceeded that of the well-characterized TNT-degrading bacterium Pseudomonas putida KT2440. In this study, a comparative genomic analysis was performed to search for the metabolic functions encoded in the genomes of these isolates that might explain their TNT-transforming phenotype, and also to look for differences with 21 other selected pseudomonads, including xenobiotics-degrading species. Comparative analysis of xenobiotic degradation pathways revealed that our isolates have the highest abundance of key enzymes related to the degradation of fluorobenzoate, TNT, and bisphenol A. Further comparisons considering only TNT-transforming pseudomonads revealed the presence of unique genes in these isolates that would likely participate directly in TNT-transformation, and others involved in the β-ketoadipate pathway for aromatic compound degradation. Lastly, the phylogenomic analysis suggested that these Antarctic isolates likely represent novel species of the genus Pseudomonas, which emphasizes their relevance as potential agents for the bioremediation of TNT and other xenobiotics.

2,4,6-trinitrotoluene (TNT) degradation by Indiicoccus explosivorum (S5-TSA-19)

2,4,6-trinitrotoluene (TNT), a nitro-aromatic explosive commonly used for defense and several non-violent applications is contributing to serious environmental pollution problems including human health. The current study investigated the remediation potential of a native soil isolate, i.e., Indiicoccus explosivorum (strain S5-TSA-19) isolated from collected samples of an explosive manufacturing site, against TNT. The survivability of I. explosivorum against explosives is indirectly justified through its isolation; thus, it is being chosen for further study. At a TNT concentration of 120 mg/L within an optimized environment (i.e., at 30 °C and 120 rpm), the isolate was continually incubated for 30 days in a minimal salt medium (MSM). The proliferation of the isolate and the concentration of TNT, nitrate, nitrite, and ammonium ion were evaluated at a particular time during the experiment. Within 168 h (i.e., 7 days) of incubation, I. explosivorum co-metabolically degraded 100% TNT. The biodegradation procedure succeeded the first-order kinetics mechanism. Formations of additional metabolites like 2,4-dinitrotoluene (DNT), 2,4-diamino-6-nitrotoluene (2-DANT), and 2-amino-4,6-dinitrotoluene (2-ADNT), were also witnessed. TNT seems to be non-toxic for the isolate, as it reproduced admirably in TNT presence. To date, it is the first report of Indiicoccus explosivorum, efficiently bio-remediating TNT, i.e., a nitro-aromatic compound via different degradation pathways, leading to the production of simpler as well as less harmful end products. Further, at the field-scale application, Indiicoccus explosivorum may be explored for the bioremediation of TNT (i.e., a nitro-aromatic compound)-contaminated effluents.

Trends in environmental monitoring of high explosives present in soil/sediment/groundwater using LC-MS/MS

Environmental contamination by explosives occurs due to improper handling and disposal procedures. Explosives and their transformation products pose threat to human health and the ecosystem. Trace level detection of explosives present in different environmental matrices is a challenge, due to the interference caused by matrix components and the presence of cocontaminants. Liquid chromatography combined with tandem mass spectrometry (LC-MS/MS) is an advanced analytical tool, which is ideal for quantitative and qualitative detection of explosives and its metabolites at trace levels. This review aims to showcase the current trends in the application of LC-MS/MS for detecting explosives present in soil, sediment, and groundwater with detection limits ranging from nano to femtogram levels. Specificity and advantages of using LC-MS/MS over conventional analytical methods and various processing methods and techniques used for sample preparation are discussed in this article. Important application aspects of LC-MS/MS on environmental monitoring include site characterization and degradation evaluation. Studies on qualitative and quantitative LC-MS/MS analysis in determining the efficiency of treatment processes and contamination mapping, optimized conditions of LC and MS/MS adopted, role of different ionization techniques and mass analyzers in detection of explosives and its metabolites, relative abundance of various product ions formed on dissociation and the levels of detection achieved are reviewed. Ionization suppression, matrix effect, additive selection are some of the major factors which influence MS/MS detection. A summary of challenges and future research insights for effective utilization of this technique in the environmental monitoring of explosives are presented.

Modification of glassy carbon electrode with manganese cobalt oxide-cubic like structures incorporated graphitic carbon nitride sheets for the voltammetric determination of 2,4,6 -trichlorophenol

Novel cube-like transition metal oxide embedded on graphitic carbon nitride (MCO@GCN) formed a hybrid composite via hydrothermal assisted sonochemical synthesis. The synthesized composite was examined with various physical characterizations such as morphological SEM, EDX, XRD, and FT-IR spectroscopy. The electrocatalytic activity of MCO@GCN composite was further investigated when used  to modify a glassy carbon electrode (GCE). The electrochemical sensor was investigated using modified MCO@GCN/GCE towards environmental pollutant 2,4,6-trichlorophenol (2,4,6-TCP) detection with at a potential of (+ 0.654 V vs Ag/AgCl) in pH-7. The structural features have favored a high charge transfer ratio with excellent conductivity which showed a low detection limit (LOD) of 0.0068 μM and sensitivity of 23.57 μA·μM^-1·cm^-2 comprising a wide linear working range of 0.01-1720 μM by using differential pulse voltammetry. Besides, the MCO@GCN/GCE displayed excellent selectivity , repeatability, reproducibility, storage, and operational stability. Notably, the proposed MCO@GCN/GCE was validated with different environmental samples (tap, river, and industrial water) with RSD 0.62-2.86% and 96.51-99.66% (n = 3) recovery.

Association Between Gut Dysbiosis and Sepsis-Induced Myocardial Dysfunction in Patients With Sepsis or Septic Shock

Objective

Sepsis-induced myocardial dysfunction (SIMD) seriously affects the evolution and prognosis of the sepsis patient. The gut microbiota has been confirmed to play an important role in sepsis or cardiovascular diseases, but the changes and roles of the gut microbiota in SIMD have not been reported yet. This study aims to assess the compositions of the gut microbiota in sepsis or septic patients with or without myocardial injury and to find the relationship between the gut microbiota and SIMD.

Methods

The prospective, observational, and 1:1 matched case–control study was conducted to observe gut microbiota profiles from patients with SIMD (n = 18) and matched non-SIMD (NSIMD) patients (n = 18) by 16S rRNA gene sequencing. Then the relationship between the relative abundance of microbial taxa and clinical indicators and clinical outcomes related to SIMD was analyzed. The receiver operating characteristic (ROC) curves were used to evaluate the predictive efficiencies of the varied gut microbiota to SIMD.

Results

SIMD was associated with poor outcomes in sepsis patients. The beta-diversity of the gut microbiota was significantly different between the SIMD patients and NSIMD subjects. The gut microbiota profiles in different levels significantly differed between the two groups. Additionally, the abundance of some microbes (Klebsiella variicola, Enterobacteriaceae, and Bacteroides vulgatus) was correlated with clinical indicators and clinical outcomes. Notably, ROC analysis indicated that K. variicola may be a potential biomarker of SIMD.

Conclusion

Our study indicates that SIMD patients may have a particular gut microbiota signature and that the gut microbiota might be a potential diagnostic marker for evaluating the risk of developing SIMD.

Four-year biochar study: Positive response of acidic soil microenvironment and citrus growth to biochar under potassium deficiency conditions

Biochar has direct or indirect effects on soil microorganisms, but the changes in soil metabolism are rarely monitored and analyzed. In addition, the potassium (K) effect of biochar has not attracted much attention. This study set up a four-year experiment with acid soil and citrus as the test soil and plants, respectively. The long-term effects of biochar on the acid soil microenvironment and citrus growth were explored from soil properties (nutrient contents, microbial communities, and metabolites) and citrus growth (nutrient contents, reactive oxygen species (ROS), and root endophytes). The results showed that the four-year amendment of biochar in acid soil was very significant, in which the soil pH was increased by 1 unit, organic matter and cation exchange capacity (CEC) increased by 120.77% and 16.21%, respectively. Biochar improved the K availability of soil by increasing the number and metabolic activity of Azotobacter and Pseudomonas, and finally effectively alleviated the K deficiency of citrus. From the perspective of available K content, 2% biochar reduced the 20% conventional K application rate. The pH, organic matter, and cation exchange capacity (CEC) were the most important factors affecting the bacterial community structure, while the fungal community was more sensitive to the change in the nutrient environment. Biochar mainly stimulated the progress of soil metabolism by affecting the metabolic activity of bacterial communities. Biochar application increased some of the beneficial bacteria in the soil, i.e., the relative abundance of Pseudarthrobacter increased by 700 times. However, biochar and exogenous K did not significantly affect arbuscular mycorrhizal fungi (AMF) and endophytic bacteria in citrus roots. In general, biochar has a long-term and positive response to the acidic soil microenvironment and citrus growth, as well as promotion value in the agricultural field.

Recruiting Perovskites to Degrade Toxic Trinitrotoluene

Everybody knows TNT, the most widely used explosive material and a universal measure of the destructiveness of explosions. A long history of use and extensive manufacture of toxic TNT leads to the accumulation of these materials in soil and groundwater, which is a significant concern for environmental safety and sustainability. Reliable and cost-efficient technologies for removing or detoxifying TNT from the environment are lacking. Despite the extreme urgency, this remains an outstanding challenge that often goes unnoticed. We report here that highly controlled energy release from explosive molecules can be accomplished rather easily by preparing TNT-perovskite mixtures with a tailored perovskite surface morphology at ambient conditions. These results offer new insight into understanding the sensitivity of high explosives to detonation initiation and enable many novel applications, such as new concepts in harvesting and converting chemical energy, the design of new, improved energetics with tunable characteristics, the development of powerful fuels and miniaturized detonators, and new ways for eliminating toxins from land and water.

Bacterial Enrichment Cultures Biotransform the Mycotoxin Deoxynivalenol into a Novel Metabolite Toxic to Plant and Porcine Cells

The mycotoxin deoxynivalenol (DON), produced in wheat, barley and maize by Fusarium graminearum and Fusarium culmorum, is threatening the health of humans and animals. With its worldwide high incidence in food and feed, mitigation strategies are needed to detoxify DON, maintaining the nutritional value and palatability of decontaminated commodities. A promising technique is biological degradation, where microorganisms are used to biotransform mycotoxins into less toxic metabolites. In this study, bacterial enrichment cultures were screened for their DON detoxification potential, where DON and its potential derivatives were monitored. The residual phytotoxicity was determined through a bioassay using the aquatic plant Lemna minor L. Two bacterial enrichment cultures were found to biotransform DON into a still highly toxic metabolite for plants. Furthermore, a cytotoxic effect was observed on the cellular viability of intestinal porcine epithelial cells. Through liquid chromatography high-resolution mass spectrometry analysis, an unknown compound was detected, and tentatively characterized with a molecular weight of 30.0 Da (i.e., CH₂O) higher than DON. Metabarcoding of the subsequently enriched bacterial communities revealed a shift towards the genera Sphingopyxis, Pseudoxanthomonas, Ochrobactrum and Pseudarthrobacter. This work describes the discovery of a novel bacterial DON-derived metabolite, toxic to plant and porcine cells.