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Microcystins (MCs) are hepatotoxic heptapeptides identified in cyanobacterial bloom-impacted waters and soils. However, their environmental fate in soils is poorly understood, preventing reliable site assessment. This study aims to clarify the variant-specific adsorption, desorption, and dissipation of MC-LR and MC-RR in agricultural soils. Results revealed that their adsorption isotherms followed the Freundlich model (R2 ≥ 0.96), exhibiting a higher nonlinear trend and lower adsorption capacity for MC-LR than for MC-RR. The soils had low desorption rates of 8.14-21.06% and 3.06-34.04%, respectively, following a 24 h desorption cycle. Pairwise comparison indicated that soil pH and clay played key roles in MC-LR adsorption and desorption, while organic matter and cation exchange capacity played key roles in those of MC-RR. MC-LR dissipation half-lives in soils were 27.18-42.52 days, compared with 35.19-43.87 days for MC-RR. Specifically, an appreciable decrease in MC concentration in sterile soils suggested the significant role of abiotic degradation. This study demonstrates that the minor structural changes in MCs might have major effects on their environmental fates in agricultural soil and indicates that the toxic effects of MCs should be of high concern due to high adsorption, low desorption, and slow dissipation.

Perfluorooctanesulfonate (PFOS) as an accumulative emerging persistent organic pollutant in crops poses severe threats to human health. Lettuce varieties that accumulate a lower amount of PFOS (low-accumulating crop variety, LACV) have been identified, but the regarding mechanisms remain unsolved. Here, rhizospheric activation, uptake, translocation, and compartmentalization of PFOS in LACV were investigated in comparison with those of high-accumulating crop variety (HACV) in terms of rhizospheric forms, transporters, and subcellular distributions of PFOS. The enhanced PFOS desorption from the rhizosphere soils by dissolved organic matter from root exudates was observed with weaker effect in LACV than in HACV. PFOS root uptake was controlled by a transporter-mediated passive process in which low activities of aquaporins and rapid-type anion channels were corrected with low expression levels of PIPs (PIP1-1 and PIP2-2) and ALMTs (ALMT10 and ALMT13) genes in LACV roots. Higher PFOS proportions in root cell walls and trophoplasts caused lower root-to-shoot transport in LACV. The ability to cope with PFOS toxicity to shoot cells was poorer in LACV relative to HACV since PFOS proportions were higher in chloroplasts but lower in vacuoles. Our findings provide novel insights into PFOS accumulation in lettuce and further understanding of multiprocess mechanisms of LACV.

Huge volumes of wastewater containing organic flotation reagents such as xanthates have been released into the environment via mining activities, greatly threatening the eco-environment safety. A simple and fast method is urgently needed for accurate analysis of various xanthates in mining and environmental water. Here, a robust method is realized for simultaneous determination of three trace xanthates (i.e., potassium ethyl xanthate, potassium butyl xanthate, and potassium isopropyl xanthate) in environmental water samples, including eutrophic water and flotation wastewater using solid phase extraction (SPE) and HPLC-MS/MS. HPLC-MS/MS parameters, SPE cartridges and eluting solvents, pH values, and SPE procedures were optimized. The new method had an excellent linearity in the range of 1-1000 μg/L (R

Phthalates (PAEs) are ubiquitous in soils and food products and thus pose a high risk to human health. Herein, genome mining revealed a great diversity of bacteria with PAEs-degrading potential. Mining of the genome of Raoultella ornithinolytica XF201, a novel strain isolated from Dongxiang wild rice rhizosphere, revealed the presence of two silenced tandem genes pcdGH (encoding protocatechuate 3,4-dioxygenase, 3,4-PCD), key aromatic ring-cleaving genes in PAEs biodegradation. Ribosome engineering was successfully utilized to activate the expression of pcdGH genes to produce 3,4-PCD in the mutant XF201-G2U5. The mutant XF201-G2U5 showed high 3,4-PCD activity and could remove 94.5 % of di-n butyl phthalate (DBP) in 72 h. The degradation kinetics obeyed the first-order kinetic model. Strain XF201-G2U5 could also degrade the other PAEs and the main intermediate metabolites, ultimately leading to tricarboxylic acid cycle. Therefore, this strategy facilitates novel bacterial resources discovery for bioremediation of PAEs and other emerging contaminants.

Recognition of substrates in cobalt crust mining areas can improve mining efficiency. Aiming at the problem of unsatisfactory performance of using single feature to recognize the seabed material of the cobalt crust mining area, a method based on multiple-feature sets is proposed. Features of the target echoes are extracted by linear prediction method and wavelet analysis methods, and the linear prediction coefficient and linear prediction cepstrum coefficient are also extracted. Meanwhile, the characteristic matrices of modulus maxima, sub-band energy and multi-resolution singular spectrum entropy are obtained, respectively. The resulting features are subsequently compressed by kernel Fisher discriminant analysis (KFDA), the output features are selected using genetic algorithm (GA) to obtain optimal feature subsets, and recognition results of classifier are chosen as genetic fitness function. The advantages of this method are that it can describe the signal features more comprehensively and select the favorable features and remove the redundant features to the greatest extent. The experimental results show the better performance of the proposed method in comparison with only using KFDA or GA.

The electrochemical oxidation method is a promising technology for the degradation of perfluorooctane sulfonate (PFOS). However, the elimination processes of PFOS are still unknown, including the electron transfer pathway, key reactive sites, and degradation mechanism. Here, we fabricated diatomite and cerium (Ce) co-modified Sb

In seafloor mining environments, ultrasonic detection is often used for underwater target recognition, and a large number of suspended particles reduce the recognition rate of single-classifier cob...

This study established a high-efficiency fluorescence quenching approach for the in situ visualization and modeling of the spatial distribution of xylanase, β-glucosidase, and phosphatase activities in plant leaves under pollution stress (namely, the leaf zymography technique, LZT). In the LZT, a membrane saturated with an enzyme-specific fluorescent substrate on the leaf surface was incubated and the fluorescence image generated on the membrane under ultraviolet light was recorded. An image-based modeling method for restoring the morphological traits of the true image by reducing noise was developed to ensure the accurate estimation of enzyme activities. The LZT could simultaneously measure 48 samples within 2 h, with good reproducibility. The results obtained by the LZT were comparable to those obtained by a conventional biochemical analysis method and presented low-cost and convenient advantages. This paper explains the theoretical basis required to investigate the realistic application of the LZT for assessing ecotoxicity in large-scale monitoring.

Arbuscular mycorrhizal fungi (AMF) can enhance cadmium (Cd) tolerance and decrease Cd uptake of rice plant. However, in these processes, the essential role of reactive oxygen species (ROS)-antioxidants interactions is so far not investigated. We inoculated AMF, Funneliformis mosseae (Fm) and Rhizophagus intraradices (Ri), to upland rice subjected to 0, 2 or 10 mg Cd kg−1 in soil. ROS, antioxidants, chlorophyll, mesophyll cell ultrastructure, Cd concentration and Cd transporters were measured. Results showed that the levels of ROS (i.e., superoxide, hydrogen peroxide and lipid peroxidation) were mitigated in +AMF + Cd treatments, especially in +Ri + Cd, compared with −AMF + Cd. For antioxidants, lower levels of catalase, peroxidase and superoxide dismutase, whereas higher levels of glutathione and glutathione peroxidase were observed in +AMF + Cd compared with −AMF + Cd. Chlorophyll content and mesophyll cell ultrastructure were improved by AMF. Cd concentrations in plants were significantly decreased in +AMF + Cd (10 mg Cd kg−1) treatments. AMF not only decreased Cd accumulation in rice but also regulated the ROS scavenging activities. The variations of ROS and antioxidants were restrained to smaller ranges by AMF. AMF may assist in Cd restriction and thus helping the host to release glutathione for ROS scavenging.

Rhizospheric degradation is a green and in situ strategy to accelerate dissipation of organic pollutants in soils. However, the mechanism on microbial degradation of phthalic acid esters (PAEs) in rhizosphere is still unclear. Here, the bacterial community and function genes in bulk and rhizospheric soils of maize (Zea mays L.) exposed to gradient concentrations of di-(2-ethylhexyl) phthalate (DEHP) were analyzed with 16 S rRNA, metagenomic sequencing and quantitative PCR (qPCR). Maize rhizosphere significantly increased the dissipation of DEHP by 4.02-11.5% in comparison with bulk soils. Bacterial community in rhizosphere exhibited more intensive response and shaped its beneficial structure and functions to DEHP stress than that in bulk soils. Both rhizospheric and pollution effects enriched more PAE-degrading bacteria (e.g., Bacillus and Rhizobium) and function genes in rhizosphere than in bulk soil, which played important roles in degradation of PAEs in rhizosphere. The PAE-degrading bacteria (including genera Sphingomonas, Sphingopyxis and Lysobacter) identified as keystone species participated in DEHP biodegradation. Identification of PAE intermediates and metagenomic reconstruction of PAE degradation pathways demonstrated that PAE-degrading bacteria degraded PAEs through cooperation with PAE-degrading and non-PAE-degrading bacteria. This study provides a comprehensive knowledge for the microbial mechanism on the superior dissipation of PAEs in rhizosphere.

Potential adverse effects of microcystin-LR (MC-LR) on soil invertebrates have not been studied. Here we investigated the mechanism of MC-LR toxicity to earthworm (Eisenia fetida) intestine at the individual level and at the cellular level. The results showed an inverse relationship between the bodyweight and survival rate of earthworms over exposure time- and MC-LR doses in soil. Dose-dependent intestinal lesions and disturbances of enzymatic activities (e.g., cellulase, Na

Uptake pathway and accumulation variation of soil and airborne phthalates (PAEs) in plastic greenhouses by vegetables remains unclear. Here, pot experiments of Chinese flowering cabbage were designed to distinguish root or leaf uptake pathways of PAEs, and investigate the mitigation of spraying PAE-degrading strain in PAE accumulation by vegetables. The results showed that leaves of Chinese flowering cabbage grown in plastic greenhouses absorbed more PAEs from air than those of outside greenhouses. Airborne PAEs were mainly stored in leaf surfaces of vegetables grown inside greenhouse, while PAEs absorbed by roots from soil were translocated and mainly stored in mesophyll, especially in cell walls and organelles. PAE concentrations in mesophyll elevated with increasing soil PAE levels, whereas those in leaf surfaces were not influenced by soil PAE levels. The values of bioconcentration factors for leaves inside greenhouses were significantly (1.39-3.47 fold) higher than those outside. PAE-degrading strain (Rhodococcus pyridinivorans XB) sprayed on leaf surfaces could grow well and Rhodococcus was the dominant genus as confirmed by Illumina high-throughput sequencing. PAE-degrading strain effectively reduced PAEs by 12.9%-34.9% in leaf surface, but not those in vegetables grown in high-PAE soil. This study demonstrated mitigation of spraying PAE-degrading strain in PAE accumulation by vegetable leaves from air of plastic greenhouse.

The succession of fungal community and effects of heavy metals on fungi during industrial-scale hyperthermophilic composting of municipal sludge remain unclear. Results showed hyperthermophilic composting enhanced decomposition and humification of municipal sludge in the short terms, while heavy metal concentrations and speciation had no significant change with high copper and zinc levels (101-122 and 292-337 mg/kg, respectively) in compost samples. The fungal community and its ecological assembly displayed dynamic change during hyperthermophilic composting. Some thermophilic-resistant fungi, such as phylum Ascomycota and genera Candida, Aspergillus, Thermomyces and Petriella dominated in hyperthermophilic phase. Heavy metals served important effects on fungal community structure and functions during composting. Some fungal drivers (e.g., Thermomyces, Petriella and Schizophyllum) and keystone fungi (e.g., Candida and Pichia) might be thermophilic- and heavy metal-resistant fungi which played important roles in decomposition and humification of municipal sludge. This study reveals fungal community accelerating humification and its influencing factors during composting.

Crops can take up and accumulate di-n-butyl phthalate (DBP), an extensively used plasticizer with endocrine disrupting effect, which poses potential risk to human health. Our previous study found the genotype variation in accumulation of DBP by different cultivars of rice (Oryza sativa L.). Nevertheless, the effect of DBP metabolism in vivo on the accumulation variation among different plant cultivars remains unknown. In this study, metabolism variation of DBP by low (Fengyousimiao) and high (Peizataifeng) DBP-accumulating cultivars of rice and the key enzymes involving in DBP metabolism in rice plants were investigated using in vivo exposure of rice plants and in vitro exposure of root crude enzyme extracts. Both mono-n-butyl phthalate (MBP) and phthalic acid (PA) were detected as DBP metabolites in all rice tissues (i.e., roots, stems, leaves) and crude enzyme extracts with MBP predominance. DBP metabolism occurred simultaneously when DBP uptake with the highest metabolism in roots in vivo. Degradation of DBP in root crude enzyme extracts fitted well with the first order kinetics (R2 = 0.49–0.76, P

Pot experiments were conducted to investigate the effects of a series of β-cyclodextrin (β-CD) on phytoremediation of soil co-contaminated with Cd and BDE-209 by amaranth (Amaranthus hypochondriacus L.) inoculated with arbuscular mycorrhizal fungus (AMF) – Rhizophagus intraradices. Results showed that the combination of mycorrhizal amaranth and 0.4% β-CD (RI+β0.4) significantly enhanced Cd concentrations and contents in shoots, total PBDEs concentration in roots, and BDE-209 dissipation in soil. Moreover, the RI+β0.4 treatment exerted the highest removal efficiency of both Cd and BDE-209. On the contrary, the xylem area, shoot Cd and BDE-209 concentrations and contents, and removal efficiency of Cd were markedly reduced in mycorrhizal amaranth with 0.8% or 1.2% β-CD treatments (RI+β0.8, RI+β1.2), compared with single inoculation treatment. The well-organized chloroplast and well-defined root anatomical structure were also observed in the treatment of RI+β0.4. Positive correlation was found between shoot biomass and chlorophyll concentrations. Shoot Cd or BDE-209 concentrations were positively correlated with xylem areas. In conclusion, mycorrhizal amaranth added with 0.4% β-CD could be used for the decontamination of soil polluted with mixture of Cd and BDE-209 due to the higher chlorophyll concentration and the larger xylem area.

A great amount of insoluble phosphate in agricultural soils is not available for crops. Three strains of bacteria (Bacillus megaterium YLYP1, Pseudomonas prosekii YLYP6 and Pseudomonas sp. YLYP29) isolated from activated sludge and soil could efficiently solubilise tricalcium phosphate. In particular, the novel strain P. prosekii YLYP6 produced 716 mg L−1 of available phosphate within 6 days under the optimal culture conditions [20 °C, pH 7.9, inoculum size of 0.5% (v:v)] determined by response surface methodology. P. prosekii YLYP6 demonstrated efficient phosphate solubilisation in response to broad variations in pH (5–9) and temperature (15–35 °C). The phosphate solubilisation curves of the strains fit well with a first-order kinetic model (R2 > 0.939), with a half-life of 1.51–5.94 d for 5.0 g L−1 calcium phosphate. Continuous culture experiments combined with scanning electron microscopic observations and gas chromatography–mass spectrometry analysis revealed that 2,3-dimethylfumaric acid, gluconic and N-butyl-tert-butylamine that were produced by P. prosekii YLYP6 were responsible for phosphate solubilisation by supplying H+ ions and organic anions. Efficient phosphate solubilisation in actual soil by P. prosekii YLYP6 demonstrated the strong application potential to reduce the use of chemical P fertilisers and the resulting agricultural nonpoint pollution.

Cadmium (Cd) is one of the hazardous environmental pollutants, and it can be harmful to human health through consumption of food-plants capable of bioaccumulating Cd. Therefore, lowering cadmium accumulation in plants is highly desirable. Here, a rice cultivar ‘Qisanzhan’ was studied using differential display reverse transcription-polymerase chain reaction (DDRT-PCR). Fifty-six differentially expressed genes were found in the root tips of 4-leaf stage rice seedlings exposed to 4 and 12 h of 50 µmol/L Cd(NO3)2 in a nutrient solution using DDRT-PCR. Further validation using semi-quantitative RT-PCR showed that the expression patterns of 16 genes were consistent with those found in DDRT-PCR. These genes encode receptor-like protein kinase, pleiotropic drug resistance protein, aquaporin protein, plasma membrane ATPase, etc. The differentially genes identified here can be used to obtain a better understanding of the molecular mechanisms of Cd absorption and accumulation in plants.

The extensive use of phthalic acid esters (PAEs) has led to their widespread distribution across various environments. As PAEs pose significant threats to human health, it is urgent to develop efficient strategies to eliminate them from environments. Bacteria-driven PAE biodegradation has been considered as an inexpensive yet effective strategy to restore the contaminated environments. Despite great advances in bacterial culturing and sequencing, the inherent complexity of indigenous microbial community hinders us to mechanistically understand in situ PAE biodegradation and efficiently harness the degrading power of bacteria. The synthetic microbial ecology provides us a simple and controllable model system to address this problem. In this review, we focus on the current progress of PAE biodegradation mediated by bacterial isolates and indigenous bacterial communities, and discuss the prospective of synthetic PAE-degrading bacterial communities in PAE biodegradation research. It is anticipated that the theories and approaches of synthetic microbial ecology will revolutionize the study of bacteria-driven PAE biodegradation and provide novel insights for developing effective bioremediation solutions.

The synergistic potential of plant essential oils (EOs) with other conventional and non-conventional antimicrobial agents is a promising strategy for increasing antimicrobial efficacy and controlling foodborne pathogens. Spoilage microorganisms are one of main concerns of seafood products, while the prevention of seafood spoilage principally requires exclusion or inactivation of microbial activity. This review provides a comprehensive overview of recent studies on the synergistic antimicrobial effect of EOs combined with other available chemicals (such as antibiotics, organic acids, and plant extracts) or physical methods (such as high hydrostatic pressure, irradiation, and vacuum-packaging) utilized to reduce the growth of foodborne pathogens and/or to extend the shelf-life of seafood products. This review highlights the synergistic ability of EOs when used as a seafood preservative, discovering the possible routes of the combined techniques for the development of a novel seafood preservation strategy.

Plant root-associated microbiome can be influenced by environmental stress like pollution. However, how organic pollution influences microbial communities in different root-associated niches and plant-microbe interaction remains unclear. We analyzed maize root-associated bacterial communities under stress of di-(2-ethylhexyl) phthalate (DEHP). The results demonstrate that structures and functions of bacterial communities are significantly different among four root-associated niches, and bacterial diversities gradually decline along bulk soil - rhizosphere - rhizoplane - endosphere. DEHP stress significantly reduces bacterial community diversities in both rhizosphere and rhizoplane, and changes their composition, enrichment and depleting process. DEHP stress led to the enrichment of some specific bacterial taxa like phthalate-degrading bacteria (e.g., Rhizobium and Agromyces) and functional genes involving in phthalate degradation (e.g., pht3 and pcaG). Notably, rhizoplane bacterial community is more sensitive to DEHP stress by enriching stress-resistant bacteria and more complex microbial network on rhizoplane than in rhizosphere. DEHP stress also disturbs the colonization and biofilm forming of root-associated bacteria on rhizoplane. Rhizoplane bacterial community is significantly correlated with maize growth while negatively influenced by DEHP stress. DEHP stress negatively influences plant-microbe interaction and inhibits maize growth. This study provides deep and comprehensive understanding for root-associated bacterial community in response to organic pollution.

The dissipation of toxic organic pollutants during plant-scale hyperthermophilic composting and the influence of microbial community remain unclear. The results of plant-scale hyperthermophilic composting of municipal sludge with green waste showed that the residual concentrations of polyaromatic hydrocarbons, phthalates, polybrominated diphenyl ethers were5 mg/kg and decreased over time, with the removal percentages from 12.1% to 51.2% during seven days of composting. High-throughput sequencingreveals that hyperthermophilic composting significantly reduced the diversity (e.g., observed species, chao1 and Shannon index) of bacterial community, shifting their structure and functions. The relative abundances of dominant phyla Proteobacteria and Firmicutes declined significantly, while those of extremophilic and heat-resisting phyla Deinococcus-Thermus and Chloroflexi increased dramatically. Some genera capable of degrading organic pollutants presented stably in sludge composts. Moreover, hyperthermophilic composting enriched the bacterial functions related to degradation and metabolism of cellulose and xenobiotics pollutants, which promoted the dissipation of organic pollutants and humification.

The low- and high-arsenic (As) transferring cultivars (LTC and HTC) of cabbage showed significant differences in As uptake and distribution. We hypothesise that chemistry of root cell wall matrix plays a critical role. LTC and HTC were treated with As and grown for 60 days. As concentration and distribution at subcellular and cell wall component (pectin, hemicellulose and lignin) levels were determined. Remodelling enzymes (PME and PAL) and functional groups of cell wall were analysed. Results showed that shoot biomass of LTC was not affected by As. Less As was accumulated in shoot of LTC than HTC. LTC allocated more As in root and majority of As was deposited in cell wall. LTC had more hemicellulose 1 (HC1) and lignin, PME and PAL activities. The uronic acid contents of pectin, HC1 or HC2 were all positively (P 0.05) correlated with As concentrations in each component, respectively. Chemistry of LTC root cell wall was remodelled in terms of changes in porosity, HC and lignin contents, and functional groups, which potentially exerted coupling effects on As entering and deposition. The LTC can restrain As in roots through changing characteristics of root cell wall matrix.

Perfluorooctanoic acid (PFOA) is bioaccumulative in crops. PFOA bioaccumulation potential varies largely among crop varieties. Root exudates are found to be associated with such variations. Concentrations of low-molecular-weight organic acids (LMWOAs) in root exudates from a PFOA-high-accumulation lettuce variety are observed significantly higher than those from PFOA-low-accumulation lettuce variety (p 80% attribution. Oxalic acid at rhizospheric concentrations (0.02-0.5 mM) can effectively inhibit PFOA sorption to soils by decreasing hydrophobic force, electrostatic attraction, ligand exchange, and cation-bridge effect. Oxalic acid enhances dissolution of metallic ions, iron/aluminum oxides, and organic matters from soils and forms oxalate-metal complexes, based on nuclear magnetic resonance spectra, ultraviolet spectra, and analyses of metal ions, iron/aluminum organometallic complexes, and dissolved organic carbon. The findings not only reveal the activation process of PFOA in soils by root exudates, particularly oxalic acid at rhizospheric concentrations, but also give an insight into the mechanism of enhancing PFOA accumulation in lettuce varieties.

This study established a high-efficiency fluorescence quenching approach for the

The growing incidence of microcystins (MCs) in the environment has become an issue of global concern for the high ecological and human health risks. Herein, a comparative adsorption of three MCs (MC-LR, MC-YR and MC-RR) by spent mushroom substrate (SMS)-derived biochars from contrasting pyrolytic conditions (temperature: 600/300 °C; and gas steam: CO2/N2) was surveyed to better understand the mechanisms and factors affecting the adsorption performance. For biochar preparation, 600 °C and CO2 led to greater levels of aromaticity, ash, SBET, and porosity, while 300 °C and N2 created more surface functional groups. The adsorption of MCs by biochars was a pH-dependent and endothermic physisorption process, following the pseudo-second-order kinetics (R2 = 0.99) and linear isotherm model (R2 > 0.88). The distribution coefficients Kd (0.98–19.2 L/kg) varied greatly among MCs (MC-YR > MC-RR > MC-LR) and biochars (BC600 > BN600 > BC300 > BN300), which depends on the combined effects of hydrophobicity, electrostatic attraction, H-bonding, cation bridging, and the amounts of adsorption sites on biochars. Higher ash, SBET, and total pore volume of BC600 facilitated the adsorption capacity for MCs relative to other biochars. Furthermore, the co-adsorption efficacy for MCs (Kd = 1.09–8.86 L/kg) was far below those for the single adsorption, indicating strong conflicts among competing MCs. This study sheds light on the roles of pyrolytic temperature and gas steam in biochar properties, and elucidates the mechanisms and factors affecting the adsorption performance of different MCs, which lays a foundation for MCs removal from water.

How nitrate (NO3-) fertilization influences ciprofloxacin (CIP) uptake by crops remains unsolved. Here, two Brassica parachinensis cultivars differing in CIP accumulation were cultivated to investigate the effects of NO3- supply on CIP uptake and the underlying mechanism. The results showed that NO3- supply effectively reduced CIP toxicity and accumulation in the two cultivars, especially in the low CIP cultivar. Moreover, NO3- supply induced different mechanisms of coping with CIP stress in the two cultivars through influencing subcellular distribution of CIP. The uptake of CIP by root was demonstrated to be a carrier-mediated, energy-consuming, and proton motive force-dependent influx process. Consequently, a mechanism of nitrate supply decreasing CIP uptake was proposed that uptake of CIP and NO3- into root cell would compete for the proton motive force and share a common energy source provided by plasma membrane H+-ATPase. Besides, regulating the concentration balances of cytoplasmic NO3- and proton by inhibiting the activities of NRase and two tonoplast proton pumps (V-ATPase and V-PPase) led to opposite effect on CIP uptake, further supporting this inference. Our results provide a novel insight into CIP uptake by plant roots, and improve the strategy of minimizing CIP accumulation in crops for food safety by fertilization management.

Microcystin-LR (MC-LR) is prevalent in water and can be translocated into soil-crop ecosystem via irrigation, overflow (pollution accident), and cyanobacterial manure applications, threatening agricultural production and human health. However, the effects of various input pathways on the bioaccumulation and toxicity of MCs in terrestrial plants have been hardly reported so far. In the present study, pot experiments were performed to compare the bioaccumulation, toxicity, and health risk of MC-LR as well as its degradation in soils among various treatments with the same total amount of added MC-LR (150 &mu, g/kg). The treatments included irrigation with polluted water (IPW), cultivation with polluted soil (CPS), and application of cyanobacterial manure (ACM). Three common leaf-vegetables in southern China were used in the pot experiments, including Ipomoea batatas L., Brassica juncea L., and Brassica alboglabra L. All leaf vegetables could bioaccumulate MC-LR under the three treatments, with much higher MC-LR bioaccumulation, especially root bioconcentration observed in ACM treatment than IPW and CPS treatments. An opposite trend in MC-LR degradation in soils of these treatments indicated that ACM could limit MC-LR degradation in soils and thus promote its bioaccumulation in the vegetables. MC-LR bioaccumulation could cause toxicity to the vegetables, with the highest toxic effects observed in ACM treatment. Similarly, bioaccumulation of MC-LR in the edible parts of the leaf-vegetables posed 1.1~4.8 fold higher human health risks in ACM treatment than in IPW and CPS treatments. The findings of this study highlighted a great concern on applications of cyanobacterial manure.

A novel PAE-hydrolyzing esterase (named Hyd) gene was screened from the genomic library of Rhodococcus sp. 2G and was successfully expressed in heterologous E. coli, which was defined as a new family of esterolytic enzymes. The purified Hyd could efficiently degrade various PAEs, displaying high activity and stability with a broad range of pH (4–10) and temperature (20–60 °C). Interaction mechanism of Hyd with dibutyl phthalate (DBP) was investigated by integrated multi-spectroscopic and docking simulation methods. Fluorescence and UV–vis spectra revealed that DBP could quench the fluorescence of Hyd through a static quenching mechanism. The results from synchronous fluorescence and CD spectra confirmed that the DBP binding to Hyd triggered conformational and micro-environmental changes of Hyd, which were characterized by increased stretching extent and random coil, and decreased α-helix and β-sheet. Molecular docking study showed that DBP could be bound to the cavity of Hyd with hydrogen bonding and hydrophobic interaction. A novel and distinctive catalytic mechanism was proposed: two key residues Thr190 and Ser191 might catalyze the hydrolysis of DBP, instead of the conserved catalytic triad (Ser-His-Asp) reported elsewhere, which was confirmed by site-directed mutagenesis.

Phthalate acid esters (PAEs) are ubiquitous pollutants in agricultural soils. Application of bioorganic fertilizer (BOF) containing beneficial microbes represents a promising approach to improve the yield and quality of crops grown in contaminated soils. In the present study, a novel multifunctional bioorganic fertilizer N-BOF was developed by using compost of sewage sludge and agricultural waste and inoculating with PAEs-degrading B. megaterium YJB3 and phosphate solubilizing B. megaterium YLYP1. Its feasibility of improving the yield and quality of vegetable grown in PAEs (including DBP and DEHP) contaminated soil was evaluated by pot experiments. The N-BOF could effectively promote plant growth, with biomass increasing by 4-66.9% and 19-110% compared to chemical (CF) and no fertilizer (CK), respectively. The concentrations of DBP and DEHP in shoots of chemically fertilised vegetable ranged 1.23-3.12 mg/kg (dry weight, DW) and 1.63-3.89 mg/kg (DW), respectively. Their concentrations were significantly decreased (p 0.05) when N-BOF was applied (1%, 2%, 5% amendment), especially at higher application rate ranging 0.11-0.3 mg/kg (DW) and 0.16-0.32 mg/kg (DW), respectively. Meanwhile, vegetable quality attributes were also significantly improved when 2% N-BOF was applied, with increase in the contents of vitamin C, vitamin B1, total protein, and starch, and decrease in the contents of nitrite and nitrate. In this case, the human health risk from consumption of the vegetable grown in PAEs-contaminated soil could be significantly reduced. Thus, our study is expected to provide an efficient way of high-value utilization of organic substrates by producing low-cost but high quality N-BOF. Future studies on the effects of N-BOF in terms of fertilizer regimes on yield and quality of the vegetable are needed, and further field studies for assessing the long-term efficacy and reliability of this promising N-BOF are also warranted.

Microbial fuel cell (MFC), a promising bio-electrochemical reactor could decompose organics in wastewater by redox processes of electro-active microorganism in anode and produce bio-energy, and the total MFC performance could mainly rely on electrochemical performance anode. Here, biomass carbon derived from municipal sludge was employed as low-cost and high-performance bio-anode for enhancing bioelectricity generation and wastewater treatment in MFC simultaneously. The electrochemical tests demonstrated that the large electrochemical active surface area, strong conductivity, and good biocompatibility in sludge carbon (SC) electrode resulted in higher power density (615.2 mW m−2) and lower power loss (5.4%) than those of none carbon (NC) electrode in long term operation. After 30-cycle of continuous running, the low loss of chemical oxygen demand (COD) removal was achieved up to 5.2%, which was smaller than that of NC electrode (14.1%), indicating that the MFC with SC anode could effectively treat wastewater and keep stable redox processes in anode electrode. After the formation of biofilm, the charge transfer resistance of SC electrode (16.38 Ω) was 72.4% lower than that of NC electrode (59.35 Ω). High-throughput analysis of biofilm exhibit Proteobacteria was the dominant electro-active bacteria, and the modification of SC could slightly change the bacterial community. Therefore, resource utilization of natural wastes provided the novel concept of anode catalyst fabrication for MFC in enhancing electron transfer, power output and wastewater decomposition.

Phthalates (PAEs) accumulated in agricultural soils and rice have increased human exposure risks. Microbial degradation could efficiently reduce the residue of organic pollutants in soil and crop plants. Here, we hypothesized that endophytic bacteria from wild rice have the potential for degradation of PAEs and plant growth promoting. The endophytic bacterial community and functional diversity in wild rice (Oryza meridionalis) were analyzed for the first time, and the potential for PAE degradation and plant growth promoting by endophytes were investigated. The results of Illumina high-throughput sequencing revealed that abundant endophytes inhabited in wild rice with Proteobacteria, Bacteroidetes, Firmicutes and Actinobacteria being the dominant phyla. Endophytic bacterial diversity and complexity were confirmed by isolation and clustering of isolates. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis demonstrated that endophytes exerted diverse functions such as plant growth promoting, xenobiotics biodegradation, pollution remediation and bacterial chemotaxis. Pure culture experiment showed that 30 isolated endophytic strains exhibited in vitro plant growth promoting activities, and rice plants inoculated with these strains confirmed their growth promoting abilities. Some endophytic strains were capable of efficiently degrading PAEs, with the highest removal percentage of di-n-butyl phthalate (DBP) up to 96.1% by Bacillus amyloliquefaciens strain L381 within 5 days. Synthetic community F and strain L381 rapidly removed DBP from soil (removing 91.0%–99.2% within 10 d and from rice plant slurry (removing 93.4%–99.2% within 5 d). These results confirmed the hypothesis and demonstrated the diversity of endophytic bacteria in wild rice with diverse functions, especially for plant growth promoting and removing PAEs. These multifunctional endophytic bacteria provided good alternatives to reduce PAE accumulation in crops and increase yield.

High-effective catalyst for activating peroxymonosulfate (PMS) to degrade pollutant in wastewater and minimize its toxicity is crucial. Herein, CoFe2O4/montmorillonite composites (CF/MO) were synthesized and used as high-effective PMS catalysts for the degradation of tetracycline (TC). The CoFe2O4 nanoparticles were firmly loaded on the surface of MO with Fe O Al bonds, preventing the leaching of metal ions and bringing superior reusability and stability. It was optimized that the 20%-CF/MO showed superior catalytic activity to activate PMS for TC degradation, and SO4 − was the dominant active species for TC complete degradation within 30 min and achieved high kinetic rate of 0.178 min−1. The ultrahigh catalytic performance toward TC degradation was ascribed to the cycles and regeneration of Co(III)/Co(II) and Fe(III)/Fe(II) synthergetic surface redox couples in the catalysts. The TC degradation pathway and reaction mechanism in the 20%-CF/MO/PMS system were also proposed based on DFT calculation. The ecotoxicity of degradation products was assessed using proteomics, and the toxicity of TC was found to decrease significantly as the reaction progressed.

A novel bacterial strain designated as Rhodococcus pyridinivorans XB, capable of utilizing various endocrine disruptor phthalates or phthalic acid (PA) as sole source of carbon and energy, was isolated from activated sludge. Under the optimal culture conditions (pH 7.08, 30.4 °C, inoculum size (OD600 nm) of 0.6) obtained by response surface methodology, di-(2-ethylhexyl) phthalate (DEHP, 200 mg/L) could be degraded by strain XB with a removal rate of 98% within 48 h. Under the observation of an atomic force microscope, it was confirmed that DEHP did not inhibit the growth of strain XB which might produce some extracellular polymeric substances as a response to DEHP stress, resulting in rapid degradation of DEHP. At initial concentrations of 50–800 mg/L DEHP, its degradation curves were well fitted with the first-order kinetic model, and the half-life of DEHP degradation varied from 5.44 to 23.5 h. The degradation intermediates of DEHP were identified by both GC–MS and high performance liquid chromatography–time of flight-mass spectrometry (HPLC–TOF-MS). Significant up-regulation was observed for the relative expression levels of genes (i.e., phthalate hydrolase, PA 3,4-dioxygenase, protocatechuate 3,4-α and 3,4-β dioxygenase) involved in DEHP degradation determined by real-time quantitative PCR (RT-qPCR). A DEHP biodegradation pathway by strain XB was proposed based on the identified intermediates and the degrading genes. Bioaugmentation of DEHP-contaminated soils with strain XB could efficiently promote DEHP removal, offering great potential in bioremediation of DEHP-contaminated environment.

Sorption of perfluorooctanoic acid (PFOA), a toxic and persistent organic pollutant, by various size fractions of an agricultural soil at environmentally relevant concentrations was evaluated. PFOA sorption to all fractions involved both film diffusion and intraparticle diffusion with the rate-limiting step by the latter. PFOA isotherm data fitted a linear model. Organic matter (OM), cation exchange capacity, pore volume, and the Brunauer-Emmett-Teller area played key roles in PFOA sorption. The sorption capacity followed the order of humic acid > clay (0.15-4.4 mm) > fine silt (1.9-39.8 mm) > coarse silt (17.3-79.4 mm) > fine sand (45.7-316.2 mm) > coarse sand (120-724.4 mm), opposite to their contributions to overall PFOA sorption due to the influence of their percentage weight in the original soil. Percentage OM content was the dominant factor controlling the fraction contributions to overall PFOA sorption, demonstrating influence of the hydrophobic force on sorption. PFOA should be highly mobile and bioavailable in soil-crop systems due to the low log Koc values.