Analysis of environmental biological effects and OBT accumulation potential of microalgae in freshwater systems exposed to tritium pollution.

The ecological risk of tritiated wastewater into the environment has attracted much attention. Assessing the ecological risk of tritium-containing pollution is crucial by studying low-activity tritium exposure's environmental and biological effects on freshwater micro-environment and the enrichment potential of organically bound tritium (OBT) in microalgae and aquatic plants. The impact of tritium-contaminated wastewater on the microenvironment of freshwater systems was analyzed using microcosm experiments to simulate tritium pollution in freshwater systems. Low activity tritium pollution (105 Bq/L) induced differences in microbial abundance, with Proteobacteria, Bacteroidota, and Desulfobacterota occupying important ecological niches in the water system. Low activity tritium (105-107 Bq/L) did not affect the growth of microalgae and aquatic plants, but OBT was significantly enriched in microalgae and two aquatic plants (Pistia stratiotes, Spirodela polyrrhiza), with the enrichment coefficients of 2.08-3.39 and 1.71-2.13, respectively. At the transcriptional level, low-activity tritium (105 Bq/L) has the risk of interfering with gene expression in aquatic plants. Four dominant cyanobacterial strains (Leptolyngbya sp., Synechococcus elongatus, Nostoc sp., and Anabaena sp.) were isolated and demonstrated good environmental adaptability to tritium pollution. Environmental factors can modify the tritium accumulation potential in cyanobacteria and microalgae, theoretically enhancing food chain transfer.

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.

Effects of long-term herbaceous plant restoration on microbial communities and metabolic profiles in coal gangue-contaminated soil.

The soil microbial diversity in the gangue accumulation area is severely stressed by a variety of heavy metals, while the influence of long-term recovery of herbaceous plants on the ecological structure of gangue-contaminated soil is to be explored. Therefore, we analysed the differences in physicochemical properties, elemental changes, microbial community structure, metabolites and expression of related pathways in soils in the 10- and 20-year herbaceous remediation areas of coal gangue. Our results showed that phosphatase, soil urease, and sucrase activities of gangue soils significantly increased in the shallow layer after herbaceous remediation. However, in zone T1 (10-year remediation zone), the contents of harmful elements, such as Thorium (Th; 1.08-fold), Arsenic (As; 0.78-fold), lead (Pb; 0.99-fold), and uranium (U; 0.77-fold), increased significantly, whereas the soil microbial abundance and diversity also showed a significant decreasing trend. Conversely, in zone T2 (20-year restoration zone), the soil pH significantly increased by 1.03- to 1.06-fold and soil acidity significantly improved. Moreover, the abundance and diversity of soil microorganisms increased significantly, the expression of carbohydrates in soil was significantly downregulated, and sucrose content was significantly negatively correlated with the abundance of microorganisms, such as Streptomyces. A significant decrease in heavy metals was observed in the soil, such as U (1.01- to 1.09-fold) and Pb (1.13- to 1.25-fold). Additionally, the thiamin synthesis pathway was inhibited in the soil of the T1 zone; the expression level of sulfur (S)-containing histidine derivatives (Ergothioneine) was significantly up-regulated by 0.56-fold in the shallow soil of the T2 zone; and the S content in the soil significantly reduced. Aromatic compounds were significantly up-regulated in the soil after 20 years of herbaceous plant remediation in coal gangue soil, and microorganisms (Sphingomonas) with significant positive correlations with benzene ring-containing metabolites, such as Sulfaphenazole, were identified.

Radon adsorption and air purification by Spanish moss (Tillandsia usneoides) and its metabolic response to radon exposure.

The capacity of Spanish moss (Tillandsia usneoides), an aerial plant, to adsorb radon (Rn) and absorb CO2 was assessed to analyze its capacity to remove pollutants from indoor air and to determine its radon (Rn) tolerance mechanism. Transcriptomics and metabolomics techniques were used to analyze the response of the plant to Rn exposure. Spanish moss absorbed indoor CO2 at night using the type of photosynthesis termed crassulacean acid metabolism. The CO2 absorption efficiency of the plant was mainly affected by the light duration and diurnal temperature differences. The highest purification efficiency was 48.25%, and the scales on the Spanish moss leaf surface were the key sites for Rn adsorption. Metabolome analysis showed that Rn exposure induced differential metabolites significantly enriched in the metabolism of lipids, amino acids, nucleotides, and carbohydrates. Transcriptome analysis showed significantly upregulated expression levels of functional genes in Rn-exposed leaves. Rn had significant effects on respiratory metabolism, as indicated by upregulated expression of metabolites and functional genes related to the glycolysis pathway, pyruvate oxidation, tricarboxylic acid cycle, and oxidative phosphorylation pathway. These responses indicated that the internal mechanism by which Spanish moss alleviates Rn stress involves an enhancement of cellular energy supplies and regulation of respiratory metabolic pathways to allow adaptation to Rn pollution.

Tritium and Carbon-14 Contamination Reshaping the Microbial Community Structure, Metabolic Network, and Element Cycle in the Seawater Environment.

The potential ecological risks caused by entering radioactive wastewater containing tritium and carbon-14 into the sea require careful evaluation. This study simulated seawater's tritium and carbon-14 pollution and analyzed the effects on the seawater and sediment microenvironments. Tritium and carbon-14 pollution primarily altered nitrogen and phosphorus metabolism in the seawater environment. Analysis by 16S rRNA sequencing showed changes in the relative abundance of microorganisms involved in carbon, nitrogen, and phosphorus metabolism and organic matter degradation in response to tritium and carbon-14 exposure. Metabonomics and metagenomic analysis showed that tritium and carbon-14 exposure interfered with gene expression involving nucleotide and amino acid metabolites, in agreement with the results seen for microbial community structure. Tritium and carbon-14 exposure also modulated the abundance of functional genes involved in carbohydrate, phosphorus, sulfur, and nitrogen metabolic pathways in sediments. Tritium and carbon-14 pollution in seawater adversely affected microbial diversity, metabolic processes, and the abundance of nutrient-cycling genes. These results provide valuable information for further evaluating the risks of tritium and carbon-14 in marine environments.

Assessing the ecological risk of tritium and Carbon-14 discharge on cyanobacteria through metabolic profiling.

The ecological risk posed by tritium (T) and carbon-14 (C-14) discharge from nuclear accidents has gained attention. This study evaluated the toxic impact of T and C-14 (at a concentration of 37 kBq/L for 15 days) on the cyanobacteria (Synechococcus elongatus). The results showed that the assimilation efficiency of cyanobacteria was significantly higher for C-14 than T, and the intracellular C-14 activity reached 30.62-40.58 kBq/kg. T and C-14 exposure had no significant effect on cell proliferation but impacted photosynthesis and respiration. T exposure increased the content of Ca, Mg, Na, P, K, and Mn, while C-14 exposure primarily affected trace element absorption in cyanobacteria. 31, 27, and 58 different metabolites (DEMs) were identified under T, C-14, and combined exposure conditions. These DEMs were enriched in the amino acid biosynthesis pathway, and nitrogen assimilation was one of the crucial pathways affected by T and C-14 exposure. The absorption of mineral elements by cyanobacteria was influenced by the variation in metabolites in the ABC transporter pathway caused by T and C-14 exposure. Our findings provide insights into the metabolic response of cyanobacteria to T and C-14 exposure and will help to guide the ecological risk evaluation of nuclear accidents.

Non-targeted metabolomics reveals the stress response of a cellulase-containing penicillium to uranium.

Human industrial activities have caused environmental uranium (U) pollution, resulting in uranium(VI) had radiotoxicity and chemical toxicity. Here, a cellulase-producing Penicillium fungus was screened and characterized by X-ray fluorescence (XRF), and Fourier transform infrared reflection (FT-IR), as well as by GC/MS metabolomics analysis, to study the response to uranium(VI) stress. The biomass of Penicillium decreased after exposure to 100 mg/L U. Uranium combined with carboxyl groups, amino groups, and phosphate groups to form uranium mineralized deposits on the surface of this fungal strain. The α-activity concentration of uranium in the strain was 2.57×106 Bq/kg, and the ß-activity concentration was 2.27×105 Bq/kg. Metabolomics analysis identified 118 different metabolites, as well as metabolic disruption of organic acids and derivatives. Further analysis showed that uranium significantly affected the metabolism of 9 amino acids in Penicillium. These amino acids were related to the TCA cycle and ABC transporter. At the same time, uranium exhibited nucleotide metabolism toxicity to Penicillium. This study provides an in-depth understanding of the uranium tolerance mechanism of Penicillium and provides a theoretical basis for Penicillium to degrade hyper-enriched plants.

Toxicity analysis of TNT to alfalfa's mineral nutrition and secondary metabolism.

KEY MESSAGE: Alfalfa has the ability to degrade TNT. TNT exposure caused root disruption of mineral nutrient metabolism. The exposure of TNT imbalanced basal cell energy metabolism. The mechanism of 2,4,6-trinitrotoluene (TNT) toxicity effects was analyzed in alfalfa (Medicago sativa L.) seedlings by examining the mineral nutrition and secondary metabolism of the plant roots. Exposure to 25-100 mg·L-1 TNT in a hydroponic solution for 72 h resulted in a TNT absorption rate of 26.8-63.0%. The contents of S, K, and B in root mineral nutrition metabolism increased significantly by 1.70-5.46 times, 1.38-4.01 times, and 1.40-4.03 times, respectively, after TNT exposure. Non-targeted metabolomics analysis of the roots identified 189 significantly upregulated metabolites and 420 significantly downregulated metabolites. The altered metabolites were primarily lipids and lipid-like molecules, and the most significant enrichment pathways were alanine, aspartate, and glutamate metabolism and glycerophospholipid metabolism. TNT itself was transformed in the root system into several intermediate products, including 4-hydroxylamino-2,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene, 2-hydroxylamino-4,6-dinitrotoluene, 2,4',6,6'-tetranitro-2',4-azoxytoluene, 4,4',6,6'-tetranitro-2,2'-azoxytoluene, and 2,4-dinitrotoluene. Overall, TNT exposure disturbed the mineral metabolism balance, and significantly interfered with basic plant metabolism.

Reshaping the microenvironment and bacterial community of TNT- and RDX-contaminated soil by combined remediation with vetiver grass (Vetiveria ziznioides) and effective microorganism (EM) flora.

Explosive pollutants remaining in global soils are serious threats to human health and ecological safety. Soils contaminated by trinitrotoluene (TNT) and cyclotrimethylene trinitramine (RDX) are simulated in this study and remediated using vetiver grass and effective microorganism (EM) flora to determine the efficacy of combined remediation in reshaping the microenvironment and bacterial community of soils contaminated by explosives. The degradation rates of TNT and RDX after 60 days of combined remediation were 95.66% and 84.37%, respectively. Soil microbial activity and enzyme activities related to the nitrogen cycle were upregulated. The content of soil elements in the remediation group changed significantly. Vetiver remediation increased the diversity and significantly changed the structure of the microbial community. Notably, bacteria, such as Sphingomonadaceae and Actinobacteriota, which can degrade explosives, occupied the soil niche, and the Proteobacteria and Bacteroidota, which are involved in sugar metabolism, showed particularly increased abundance. The metabolism of soil carbohydrates, fatty acids, and amino acids was upregulated in the vetiver, EM flora, and combined vetiver+EM flora remediation groups, and the most significantly upregulated pathway was galactose metabolism. The combined vetiver and EM flora treatment of soil contaminated by explosives greatly improved the ecology of the soil microenvironment.

In situ restoration of soil ecological function in a coal gangue reclamation area after 10 years of elm/poplar phytoremediation.

The soil ecological health risks and toxic effects of coal gangue accumulation were examined after 10 years of elm/poplar phytoremediation. The changes in soil enzyme activities, ionome metabolism, and microbial community structure were analyzed at shallow (5-15 cm), intermediate (25-35 cm), and deep (45-55 cm) soil depths. Soil acid phosphatase activity in the restoration area increased significantly by 4.36-7.18 fold (p < 0.05). Soil concentrations of the metal ions Cu, Pb, Ni, Co, Bi, U, and Th were significantly reduced, as were concentrations of the non-metallic element S. The repair effect was shallow > middle > deep. The soil community structure, determined by 16S diversity results, was changed significantly in the restoration area, and the abundance of microorganisms increased at shallow soil depths. Altererythrobacter and Sphingomonas species were at the center of the microbial weight network in the restoration area. Redundancy analysis (RDA) showed that S and Na are important driving forces for the microbial community distributions at shallow soil depths. The KEGG function prediction indicated enhancement of the microbial function of the middle depth soil layers in the restoration area. Overall, phytoremediation enhanced the biotransformation of soil phosphorus in the coal gangue restoration area, reduced the soil content of several harmful metal elements, significantly changed the structure and function of the microbial community, and improved the overall soil ecological environment.

Phytotoxicity mechanism of the natural radionuclide thorium in Vicia faba.

Elucidation of the phytotoxic mechanisms of thorium (Th) is important for controlling Th accumulation in crops and improving the efficiency of phytoremediation. Here, we analyzed the subcellular distribution of Th in Vicia faba seedlings and the toxic reaction of seedlings to Th (5-40 µmol·L-1) at the subcellular and cellular levels. Increasing the phosphate level in the culture medium from 0.01 to 0.1 mmol·L-1 decreased the Th accumulation by the roots by 47-57%. Th was mainly distributed in the root cell walls (94-96%) and existed mainly in the form of residue (92-94%). Th accumulation in the root was similar to the changes observed for P, Ni, Cu, and Fe. High concentrations of Th (40 µmol·L-1) induced abnormal root growth and leaf photosynthetic metabolism. At the cellular level, Th (40 µmol·L-1) induced root edge cell death and inhibited root respiration and cell mitosis. SOD, POD and CAT activities were involved in the regulation of reactive oxygen species accumulation in the roots. Untargeted metabolomics identified 580 and 262 differentially expressed metabolites in roots and leaves. At the metabolic level, its toxicological mechanism involved a severe inhibition of the expression of nucleotides in roots and leaves.

Alterations of the rhizosphere soil microbial community composition and metabolite profiles of Zea mays by polyethylene-particles of different molecular weights.

Polyethylene film is the most widely used plastic film in agricultural production activities, and its depolymerization products are mainly polyethylene-particles (PE-particles) of different molecular weights. However, the impact of the molecular weights of the PE-particles on soil-crop microenvironment has not been elucidated. In this study, a potted microcosmic simulation system was used to evaluate the impact of low, medium and high molecular weight PE-particles on soil metabolism, microbial community structure, and crop growth. There were obvious differences in the shape and surface microstructure of PE-particles with different molecular weights. Soil sucrase and peroxidase had significant responses to PE-particles of different molecular weights. In the rhizosphere, the number of microorganisms and the microbial alpha diversity index increased with increasing PE-particles molecular weight. Rhizobacter, Nitrospira, and Sphingomonas were the dominant microorganisms induced by PE-particles to regulate the metabolism of elements. Carbohydrate and amino acid contents in rhizosphere soils were the key factors affecting the species abundance of Lysobacter, Polyclovorans, Rhizobacter, and Sphingomonas. In plants, PE-particles treatment reduced the plant biomass and photosynthetic rate and disrupted normal mineral nutrient metabolism. Different molecular weight PE-particles may therefore have adverse effects on the soil-plant system.

Adsorption and enrichment of U in a cellulase-producing Trichoderma sp. and its physiological response mechanism.

The cellulase produced by Trichoderma sp. was characterized by investigating the adsorption and enrichment of U and the physiological response to U exposure. The effects of U exposure (0 and 400 µM) on the growth, morphological characteristics, cellulase production, U adsorption, and U enrichment capacity of the Trichoderma strain were assessed. The effects of U exposure on the basic metabolism of this fungus were also analyzed by non-targeted metabolomics. Exposure to U (400 µM) for 24 h resulted in OD600 turbidity of 0.278, and activities of carboxymethyl cellulase (CMC), filter paper enzyme (FPA), and ß-glucosidase of 12834 U·mL-1, 9285 U·mL-1, and 12574 U·mL-1, respectively. The measurement of the background α and ß radioactivity showed an α activity concentration of 3.35 × 106 Bq·kg-1 in the fungus, a ß activity concentration of 6.28 × 105 Bq·kg-1, and a U enrichment rate of 70.4 ± 4.5%. GC-MS metabolomics analysis identified a total of 319 metabolites (34 up-regulated and 30 down-regulated), which mainly caused the metabolic imbalance of organic acids and derivatives. The alanine, aspartate, and glutamate metabolic pathways were the most significantly enriched. Trichoderma sp. therefore has a strong ability to tolerate/accumulate U and continues to produce cellulase under U (400 µM) exposure. However, U interferes with the basic metabolism of this fungus.

Effects of polystyrene nanoplastics (PSNPs) on the physiology and molecular metabolism of corn (Zea mays L.) seedlings.

The effects of polystyrene nanoplastics (PSNPs) on the physiological and molecular metabolism of corn seedlings were examined by treating corn (Zea mays L.) seedlings with 100, 300, and 500 nm diameter PSNPs and examining plant photosynthetic characteristics, antioxidant enzyme systems, and molecular metabolism. After 15 days of exposure to PSNPs with different particle sizes (50 mg·L-1), the photosynthetic characteristics of the plant remained stable, and the maximum photochemical quantum yield (Fv/Fm) and non-photochemical quenching coefficient (NPQ) had no significant effects. The root microstructure was damaged and the antioxidant enzyme system was activated, and the content of malondialdehyde (MDA) was significantly increased by 2.25-4.50-fold. In addition, 100 nm and 300 nm PSNPs exposure caused root superoxide dismutase (SOD) activity to increase 1.28-fold and 1.53-fold, and glutathione-peroxidase (GSH-PX) activity increased 1.30-fold and 1.58-fold. Non-targeted metabolomics analysis identified a total of 304 metabolites. Exposure to 100, 300, and 500 nm PSNPs led to the production of 85 (upregulated: 85, downregulated: 0), 73 (upregulated: 73, downregulated: 0), and 86 (upregulated: 84, downregulated: 2) differentially expressed metabolites, respectively, in the plant roots. Co-expressed differential metabolites accounted for 38.2% of the metabolites and indicated a metabolic imbalance primarily in organic acids and derivatives in the root system. The most significant enrichment pathways were those of alanine, aspartate, and glutamate metabolism. Overall, exposure to PSNPs of different particle sizes activated the root antioxidant enzyme system and interfered with plant basic metabolism. The alanine, aspartate, and glutamate metabolic pathways appear to be closely related to plant mechanisms for tolerance/detoxification of PSNPs.

Degradation of Uranium-Contaminated Decontamination Film by UV Irradiation and Microbial Biodegradation.

This research provides a complete degradation scheme for acrylic copolymer/cellulose acetate butyrate peelable decontamination films. This study analyzed the removal efficiency of uranium by peelable decontamination film. More importantly, the degradability of the films was evaluated by a combined treatment with UV radiation and microbial biodegradation. The results showed that UV radiation would rupture the surface of the decontamination films, which leaded the weight-average molecular weight decreased by 55.3% and number-average molecular weight decreased by 75.83%. Additionally, the microbial flora induced light-degradable decontamination film weight-average molecular weight and number-average molecular weight decreased by 9.3% and 30.73%, respectively. 16S rRNA microbial diversity analysis indicated that Pantoea, Xylella, Cronobacter, and Olivibacter were the major degrading bacteria genera. Among them, 4 key strains that can be stripped of decontamination films have been isolated and identified from the dominant degrading bacteria group. The results show that UV radiation combined with microbial flora can achieve rapid degradation of the decontamination films.

Microbial community structure and metabolome profiling characteristics of soil contaminated by TNT, RDX, and HMX.

This experiment was conducted to evaluate the ecotoxicity of typical explosives and their mechanisms in the soil microenvironment. Here, TNT (trinitrotoluene), RDX (cyclotrimethylene trinitramine), and HMX (cyclotetramethylene tetranitramine) were used to simulate the soil pollution of single explosives and their combination. The changes in soil enzyme activity and microbial community structure and function were analyzed in soil, and the effects of explosives exposure on the soil metabolic spectrum were revealed by non-targeted metabonomics. TNT, RDX, and HMX exposure significantly inhibited soil microbial respiration and urease and dehydrogenase activities. Explosives treatment reduced the diversity and richness of the soil microbial community structure, and the microorganisms able to degrade explosives began to occupy the soil niche, with the Sphingomonadaceae, Actinobacteria, and Gammaproteobacteria showing significantly increased relative abundances. Non-targeted metabonomics analysis showed that the main soil differential metabolites under explosives stress were lipids and lipid-like molecules, organic acids and derivatives, with the phosphotransferase system (PTS) pathway the most enriched pathway. The metabolic pathways for carbohydrates, lipids, and amino acids in soil were specifically inhibited. Therefore, residues of TNT, RDX, and HMX in the soil could inhibit soil metabolic processes and change the structure of the soil microbial community.

Analysis of the biodegradation and phytotoxicity mechanism of TNT, RDX, HMX in alfalfa (Medicago sativa).

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.

Biodegradation and physiological response mechanism of Bacillus aryabhattai to cyclotetramethylenete-tranitramine (HMX) contamination.

This study aims to reveal the biodegradation and interaction mechanism of cyclotetramethylenete-tranitramine (HMX) by a newly isolated bacteria. In this study, a bacterial strain (Bacillus aryabhattai) with high efficiency for HMX degradation was used as the test organism to analyze the changes in growth status, cell function, and mineral metabolism following exposure to different stress concentrations (0 and 5 mg L-1) of HMX. Non-targeted metabonomics was used to reveal the metabolic response of this strain to HMX stress. The results showed that when the HMX concentration was 5 mg L-1, the removal rate of HMX within 24 h of inoculation with Bacillus aryabhatta was as high as 90.5%, the OD600 turbidity was 1.024, and the BOD5 was 225 mg L-1. Scanning electron microscope (SEM) images showed that the morphology of bacteria was not obvious Variety, Fourier transform infrared spectroscopy (FTIR) showed that the cell surface -OH functional groups drifted, and ICP-MS showed that the cell mineral element metabolism was disturbed. Non-targeted metabonomics showed that HMX induced the differential expression of 254 metabolites (133 upregulated and 221 downregulated). The main differentially expressed metabolites during HMX stress were lipids and lipid-like molecules, and the most significantly affected metabolic pathway was purine metabolism. At the same time, the primary metabolic network of bacteria was disordered. These results confirmed that Bacillus aryabhattai has a high tolerance to HMX and can efficiently degrade HMX. The degradation mechanism involves the extracellular decomposition of HMX and transformation of the degradation products into intracellular purines, amino sugars, and nucleoside sugars that then participate in cell metabolism.

Analysis of accumulation and phytotoxicity mechanism of uranium and cadmium in two sweet potato cultivars.

The purpose of this study was to reveal the accumulation and phytotoxicity mechanism of sweet potato (Ipomoea batatas L.) roots following exposure to toxic levels of uranium (U) and cadmium (Cd). We selected two accumulation-type sweet potato cultivars as experimental material. The varietal differences in U and Cd accumulation and physiological metabolism were analyzed by a hydroponic experiment. High concentrations of U and Cd inhibited the growth and development of sweet potato and damaged the microstructure of root. The roots were the main accumulating organs of U and Cd in both sweet potato. Root cell walls and vacuoles (soluble components) were the main distribution sites of U and Cd. The chemical forms of U in the two sweet potato varieties were insoluble and oxalate compounds, while Cd mainly combined with pectin and protein. U and Cd changed the normal mineral nutrition metabolism in the roots, and also significantly inhibited the photosynthetic metabolism of sweet potatoes. RNA-seq showed that the cell wall and plant hormone signal transduction pathways responded to either U or Cd toxicity in both varieties. The inorganic ion transporter and organic compound transporter in roots of both sweet potato varieties are sensitive to U and Cd toxicity.