An in Silico Study on Human Carcinogenicity Mechanism of Polybrominated Biphenyls Exposure.

Polybrominated biphenyls (PBBs) are associated with an increased risk of thyroid cancer; however, relevant mechanistic studies are lacking. In this study, we investigated the mechanisms underlying PBB-induced human thyroid cancer. Molecular docking and molecular dynamics methods were employed to investigate the metabolism of PBBs by the cytochrome P450 enzyme under aryl hydrocarbon receptor mediation into mono- and di-hydroxylated metabolites. This was taken as the molecular initiation event. Subsequently, considering the interactions of PBBs and their metabolites with the thyroxine-binding globulin protein as key events, an adverse outcome pathway for thyroid cancer caused by PBBs exposure was constructed. Based on 2D quantitative structure activity relationship (2D-QSAR) models, the contribution of amino acid residues and binding energy were analyzed to understand the mechanism underlying human carcinogenicity (adverse effect) of PBBs. Hydrogen bond and van der Waals interactions were identified as key factors influencing the carcinogenic adverse outcome pathway of PBBs. Analysis of non-bonding forces revealed that PBBs and their hydroxylation products were predominantly bound to the thyroxine-binding globulin protein through hydrophobic and hydrogen bond interactions. The key amino acids involved in hydrophobic interactions were alanine 330, arginine 381 and lysine 270, and the key amino acids involved in hydrogen bond interactions were arginine 381 and lysine 270. This study provides valuable insights into the mechanisms underlying human health risk associated with PBBs exposure.

Risk mitigation strategy and mechanism analysis of neonicotinoid pesticides on earthworms.

Neonicotinoid insecticides (NNIs) are a new class of widely used insecticides with certain risks to non-target organisms, like earthworms. The gray correlation method was used to calculate the comprehensive risk effect value of acute toxicity (LC50) and bioaccumulation (logKow) of NNIs on earthworms. A comprehensive effects three-dimensional quantitative structure-activity relationship (3D-QSAR) model was constructed, using NNIs molecular structures and the comprehensive effect value as the independent and dependent variables, respectively. One of the representatives guadipyr (GUA) was selected as the template molecule for the molecular design and modification. A total of 63 NNIs alternatives were designed with a reduced comprehensive value higher than 10%, and as high as 42%. After screening, 15 NNIs alternatives were screened with decreased acute toxicity to earthworms, bioaccumulation effects and improved functional property. The calculated primary acute risk quotient of earthworms shows that the designed NNIs alternatives have lower earthworm risks (reduction of 70.48-99.99%). Results also found that the electronic, geometric and topological parameters of NNIs are the key descriptors that affect NNIs alternatives' toxicity. The number of hydrophobic interaction amino acid residues in NNIs molecules also contributes to the acute toxicity and the bioaccumulation of NNIs alternatives on earthworms. This study aims to design and screen functionally improved and environmentally friendly NNIs alternatives that have low risk to earthworms and provide theoretical methods and new ideas for the risk control and development of pesticides represented by NNIs.

Role of rice cultivation on fluorine distribution behavior in soda saline-alkali land.

Fluorine stability in the soil is crucial to protecting the groundwater and the food chain from pollution by fluorine, which was abundantly present (762.78-1330.66 mg/kg) in soda saline-alkali soil areas of western Jilin Province. This study investigated the fluorine distribution and pollution level in soil. Two representative areas in Zhenlai County, namely Chagan and Hatu villages, were selected to gather soda saline-alkali soil profiles (0-20, 20-40, and 40-60 cm) from different cultivation years (i.e. 3, 5, 8, 10, 13, 15, 18, and 20). The results revealed that fluorine content in soil decreased with increasing cultivation years. In the soil profiles, fluorine and water-soluble fluorine concentrations followed the order of 40-60 > 20-40 > 0-20 cm, while the contents of exchangeable and organic matter-bound fluorine decreased with the increasing profile depth. Rice planting increased the content of macroaggregates with diameters >2 and 2-0.25 mm, which significantly improved the aggregate structure of the soil. The fluorine content was the greatest in microaggregate with particle sizes <0.053 mm in the aggregates' sizes. Rice planting in saline-alkali soil reduced the contents of water-soluble and exchangeable fluorine, while enhancing the content of organic matter-bound fluorine, thereby reducing the bioavailability of fluorine in the soil and the risk of fluorine migration through the groundwater. The degree of soil pollution decreased with increasing plantation years, and the soil became slightly polluted after 15 years of rice planting. The rice plants grew normally after years of improving fluorine-containing saline-alkali land, and the fluorine content was within the safe limit.

Extracellular polymeric substance from Rahnella sp. LRP3 converts available Cu into Cu5(PO4)2(OH)4 in soil through biomineralization process.

Soil contamination by toxic heavy metals such as copper is a serious problem. In this study, the extracellular polymeric substance (EPS) extracted from Rahnella sp. LRP3 was found with the potential of immobilizing Cu-polluted in soil. The EPS could bond to Cu (II) through functional groups (polysaccharides, amide, proteins, and carboxyl groups), which further developed into the porous sphere with a diameter of 20 µm. Besides, EPS could induce the formation of Cu5(PO4)2(OH)4 crystal by the biomineralization process. Finally, the EPS in the culture solution reduced 89.4 mg/kg of DTPA-Cu content by 78.99% in soil for 10 d under the condition of 25 °C via biomineralization. The results demonstrated that EPS produced by Rahnella sp. LRP3 will be a promising factor in the remediation of Cu contaminated soil.

The effect of tillage systems on phosphorus distribution and forms in rhizosphere and non-rhizosphere soil under maize (Zea mays L.) in Northeast China.

An appropriate tillage method must be implemented by maize growers to improve phosphorus dynamics in the soil in order to increase phosphorus uptake by plant. The objective of this study was to investigate the effects of tillage systems on phosphorus and its fractions in rhizosphere and non-rhizosphere soils under maize. An experimental field was established, with phosphate fertilizers applied to four treatment plots: continuous rotary tillage (CR), continuous no-tillage (CN), plowing-rotary tillage (PR), and plowing-no tillage (PN). Under the different tillage methods, the available P was increased in the non-rhizosphere region. However, the concentration of available P was reduced in the rhizosphere soil region. The soil available P decreased with the age of the crop until the maize reached physiological maturity. The non-rhizosphere region had 132.9%, 82.5%, 259.8%, and 148.4% more available P than the rhizosphere region under the CR, PR, CN, and PN treatments, respectively. The continuous no-tillage method (CN) improved the uptake of soil phosphate by maize. The concentrations of Ca2-P, Ca8-P, Fe-P, Al-P and O-P at the maturity stage were significantly lower than other seedling stages. However, there was no significant relationship between total P and the P fractions. Therefore, a continuous no-tillage method (CN) can be used by farmers to improve phosphorus availability for spring maize. Soil management practices minimizing soil disturbance can be used to impove phosphorus availability for maize roots, increase alkaline phosphatase activity in the rhizosphere soil and increase the abundance of different phosphorus fractions.

Active 3D Imaging of Vegetation based on Multi-Wavelength Fluorescence LiDAR.

Comprehensive and accurate vegetation monitoring is required in forestry and agricultural applications. The optical remote sensing method could be a solution. However, the traditional light detection and ranging (LiDAR) scans a surface to create point clouds and provide only 3D-state information. Active laser-induced fluorescence (LIF) only measures the photosynthesis and biochemical status of vegetation and lacks information about spatial structures. In this work, we present a new Multi-Wavelength Fluorescence LiDAR (MWFL) system. The system extended the multi-channel fluorescence detection of LIF on the basis of the LiDAR scanning and ranging mechanism. Based on the principle prototype of the MWFL system, we carried out vegetation-monitoring experiments in the laboratory. The results showed that MWFL simultaneously acquires the 3D spatial structure and physiological states for precision vegetation monitoring. Laboratory experiments on interior scenes verified the system's performance. Fluorescence point cloud classification results were evaluated at four wavelengths and by comparing them with normal vectors, to assess the MWFL system capabilities. The overall classification accuracy and Kappa coefficient increased from 70.7% and 0.17 at the single wavelength to 88.9% and 0.75 at four wavelengths. The overall classification accuracy and Kappa coefficient improved from 76.2% and 0.29 at the normal vectors to 92.5% and 0.84 at the normal vectors with four wavelengths. The study demonstrated that active 3D fluorescence imaging of vegetation based on the MWFL system has a great application potential in the field of remote sensing detection and vegetation monitoring.

Rahnella sp. LRP3 induces phosphate precipitation of Cu (II) and its role in copper-contaminated soil remediation.

Microbially induced phosphate precipitation (MIPP) is an advanced bioremediation technology to immobilize heavy metals in soil. In this study, an indigenous bacterial strain LRP3, identified as Rahnella sp., was isolated from Cu-contaminated dark brown soil in the mining area. Strain LRP3 could produce phytase and alkaline phosphatase to degrade phytic acid, which released soluble phosphate to the bacterial culture. Due to the metabolism of bacterial growth, the pH value of bacterial culture was increased. The minimum inhibitory concentration of Cu (II) to bacterial growth in solution was up to 130 mg/L. The bacterial culture could rapidly precipitate Cu (II) in solution through MIPP. The analysis results of Scanning Electron Microscope-Energy Dispersive Spectroscopy (SEM-EDS), Fourier Transform-Infrared Spectrometer (FTIR), and X-ray Diffraction (XRD) revealed that the precipitate form by bacterial culture was rod-shaped Cu3(OH)3PO4 crystal with a diameter of 10 µm. The bacterial culture decreased the content of DTPA-Cu of 83 mg/kg soil in the soil by 58.2%, 61.5% and 75.8% after 5, 10 and 30 days of incubation, respectively, at the temperature of 25 °C. The results indicate that MIPP-based bioremediation by Rahnella sp. LRP3 is a practical, environmental friendly technology for the cleaning-up of copper-contaminated soil.

Organic carbon content and humus composition after application aluminum sulfate and rice straw to soda saline-alkaline soil.

The soil organic carbon accumulation in soda saline-alkaline soil and the humus composition changes with application of aluminum sulfate and rice straw were investigated by the controlled simulative experiments in laboratory. For evaluating the amelioration effect, organic carbon content and humus composition in soda saline-alkaline soil were investigated with different application amounts of rice straw and aluminum sulfate. Potassium dichromate oxidation titration (exogenous heat) method and Kumada method were used to analyze the contents of organic carbon and humus composition, respectively. The transformation of soil organic matter in the saline-alkali soil during the amelioration has been clarified in this paper. The results demonstrated that the contents of soil organic carbon were significantly increased (13-92%) with different application amounts of rice straw and aluminum sulfate. The contents of free fraction and combined fraction of humus and their compositions (humic acid and fulvic acid) were increased with different application amounts of rice straw. The free fraction of humus was increased more dramatically. Due to aluminum sulfate application, free fraction of humus and humic acid (HA) was transformed to combined fraction partially. Free HA was changed to be P type with rice straw application. With aluminum sulfate application, free form of HA was changed from type P to type Rp. For rice straw application, combined HA only was transferred within the area of type A. Aluminum sulfate addition had no significant effect on the type of combined form of HA. With the same amount of rice straw application, the contents of soil organic carbon were increased by increasing the amount of aluminum sulfate application. Both rice straw and aluminum sulfate applications could reduce the humification degree of free and combined fraction of HA. According to the types of HA, it could be concluded that humus became younger and renewed due to the application of rice straw and aluminum sulfate.

Biodegradation of 17ß-estradiol by Bacterial Co-culture Isolated from Manure.

Animal wastes are potential sources of natural and steroidal estrogen hormones into the environment. These hormones can be removed by microorganisms with induced enzymes. Two strains of 17ß-estradiol-degrading bacteria (LM1 and LY1) were isolated from animal wastes. Based on biochemical characteristics and 16 S rDNA gene sequences, we identified strains LM1 and LY1 as belonging to the genus of Acinetobacter and Pseudomonas, respectively. Bacterial co-culture containing LM1 and LY1 bacterial strains could rapidly remove approximately 98% of E2 (5 mg L-1) within 7 days. However, strains LM1 and LY1 degraded 77% and 68% of E2 when they were incubated alone, respectively. More than 90% of 17ß-estradiol (E2, ≤ 20 mg L-1) could be removed by bacterial co-culture. Low C/N ratio (1:35) was more suitable for bacterial growth and E2 degradation. The optimal pH for bacterial co-culture to degrade E2 ranged from 7.00 to 9.00. Coexisting sodium acetate, glucose and sodium citrate decreased E2 degradation in the first 4 days, but more E2 was removed when they were depleted. The growth of the bacterial co-culture was not significantly decreased by Ni, Pb, Cd or Cu at or below 0.8, 1.2, 1.6 or 0.8 mg L-1, respectively. These data highlight the usefulness of bacterial co-culture in the bioremediation of estrogen-contaminated environments.

Microwave assisted digestion followed by ICP-MS for determination of trace metals in atmospheric and lake ecosystem.

The study of trace metals in the atmosphere and lake water is important due to their critical effects on humans, aquatic animals and the geochemical balance of ecosystems. The objective of this study was to investigate the concentration of trace metals in atmospheric and lake water samples during the rainy season (before and after precipitation) between November and December 2015. Typical methods of sample preparation for trace metal determination such as cloud point extraction, solid phase extraction and dispersive liquid-liquid micro-extraction are time-consuming and difficult to perform; therefore, there is a crucial need for development of more effective sample preparation procedure. A convection microwave assisted digestion procedure for extraction of trace metals was developed for use prior to inductively couple plasma-mass spectrometric determination. The result showed that metals like zinc (133.50-419.30µg/m3) and aluminum (53.58-378.93µg/m3) had higher concentrations in atmospheric samples as compared to lake samples before precipitation. On the other hand, the concentrations of zinc, aluminum, chromium and arsenic were significantly higher in lake samples after precipitation and lower in atmospheric samples. The relationship between physicochemical parameters (pH and turbidity) and heavy metal concentrations was investigated as well. Furthermore, enrichment factor analysis indicated that anthropogenic sources such as soil dust, biomass burning and fuel combustion influenced the metal concentrations in the atmosphere.

Description of Sphingomonas mohensis sp. nov., Isolated from Sediment.

An aerobic, gram-reaction-negative, rod-shaped bacterium, designated strain Z6(T), was isolated from sediment collected at Mohe Basin, China. And its taxonomic position was investigated by applying a polyphasic approach. Growth occurs at 10-45 °C (optimum, 30 °C), at pH 6.0-11.0 (optimum, pH 7.0) and in the presence of 0-3.0 % (w/v) NaCl (optimum, 0 %). The polar lipid profile of strain Z6(T) revealed the presence of diphosphatidylglycerol, phosphatidylethanolamine, sphingoglycolipid and two unidentified phospholipids, and the major quinone was Q-10. The major fatty acids were C18:1 ω7c and/or C18:1 ω6c (summed feature 8) and C16:1 ω6c and/or C16:1 ω7c (summed feature 3). The predominant polyamine was homospermidine. The DNA G + C content of strain Z6(T) is 65.2 mol%. On the basis of the polyphasic evidence presented, strain Z6(T) represents a novel species of the genus Sphingomonas, for which the name Sphingomonas mohensis sp. nov. is proposed. The type strain is Z6(T) (=CGMCC 1.12891(T) = JCM 19983(T)).

Altererythrobacter buctense sp. nov., isolated from mudstone core.

A yellow-pigmented, Gram-negative, non-flagellated, rod-shaped bacterial strain, designated M0322(T), was isolated from a mudstone core sample of the Mohe Basin, China. Growth of strain M0322(T) was observed at 15-40 °C (optimum, 30 °C), at pH 5.0-10.0, (optimum, pH 6.0-7.0) and in the presence 0-4 % NaCl (optimum, 0 %). Phylogenetic analyses of 16S rRNA gene sequences revealed that strain M0322(T) formed a distinct phyletic lineage with the members of the genus Altererythrobacter and is closely related to Altererythrobacter aestuarii JCM 16339(T) (96.1 %) and Altererythrobacter namhicola JCM 16345(T) (95.7 %). The only isoprenoid quinone was identified as ubiquinone 10 (Q-10), major polar lipids were determined to be phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, one unidentified glycolipid and three unidentified phospholipids, while major cellular fatty acids were summed feature 8 (C18:1 ω6c and/or C18:1 ω7c), summed feature 3 (C16:1 ω6c and/or C16:1 ω7c) and 11-Methyl C18:1 ω7c. The DNA G+C content of strain M0322(T) was determined to be 64.6 mol%. Based on the results of the polyphasic taxonomic study, strain M0322(T) is considered to represent a novel species of the genus Altererythrobacter, for which the name Altererythrobacter buctense sp. nov. is proposed. The type strain is M0322(T) (=CGMCC 1.12871(T) = JCM 30112(T)).

Chromium(VI) transport and fate in unsaturated zone and aquifer: 3D Sandbox results.

The simulation of Cr(VI) behavior in an unsaturated zone and aquifer, using a 3D experimental set-up were performed to illustrate the distribution, transport and transformation of Cr(VI), and further to reveal the potential harm of Cr(VI) after entering the groundwater. The result indicated that chromium(VI) was transported in the vertical direction, meanwhile, was transported in the horizontal direction under the influence of groundwater flow. The direction and distance away from the pollution source zone had great effect on the chromium(VI) concentration. At the sampling sites near the pollution source zone, there was a sudden increase of chromium(VI) concentration. The concentration of chromium(III) concentration in some random effluent samples was not detected. Chromium had not only transported but also had fraction and specie transformation in the unsaturated zone and aquifer. The relative concentration of residue fraction chromium was decreased with time. The content of Fe-Mn oxide fraction chromium was increased with time. The relative content of exchangeable and carbonate-bound fraction chromium was lower and the content variations were not obvious. Chromium(VI) (91-98%) was first reduced to chromium(III) rapidly. The oxidation reaction occurred later and the relative content of chromium(VI) was increased again. The presence of manganese oxides under favorable soil conditions can promote the reoxidation of Cr(III) to Cr(VI).

Tianweitania sediminis gen. nov., sp. nov., a member of the family Phyllobacteriaceae, isolated from subsurface sediment core.

A bacterial strain, designated Z8T, was isolated from the terrestrial sediment of the Mohe Basin in north-east China. Phylogenetic analyses of 16S rRNA genes showed that this strain belonged to the family Phyllobacteriaceae, and was most closely related to Phyllobacterium bourgognense, with a sequence similarity of 96.9 %. The major cellular fatty acids were summed feature 4 (iso-C17 : 1 I and/or anteiso-C17 : 1 B) and summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c). The major respiratory quinone was ubiquinone-10. The three major polar lipids of strain Z8T consisted of glycolipids, phosphatidylethanolamine and phosphatidylmethylethanolamine. The DNA G+C content was 59.6 mol%. The chemotaxonomic characteristics of strain Z8T differed in some respects from those of members of the family Phyllobacteriaceae. Based on phylogenetic, phenotypic and chemotaxonomic data, strain Z8T is considered to represent a novel species of a novel genus within the family Phyllobacteriaceae, for which the name Tianweitania sediminis gen. nov., sp. nov. is proposed. The type strain is Z8T ( = CGMCC 1.12944T = JCM 30358T).

Dyadobacter sediminis sp. nov., isolated from a subterranean sediment sample.

A Gram-reaction-negative, flexirubin-type-pigmented, rod-shaped, aerobic, non-motile bacterium, designated strain Z12(T), was isolated from a subsurface sediment sample. In a phylogenetic tree based on 16S rRNA gene sequences, strain Z12(T) formed a distinct clade with the members of the genus Dyadobacter (<96.7 % sequence similarity). The G+C content of genomic DNA was 45.4 %. The major fatty acids of strain Z12(T) were iso-C15 : 0, C16 : 1ω6c and/or C16 : 1ω7c (summed feature 3) and anteiso-C17 : 1 B and/or iso-C17 : 1 I (summed feature 4). The major respiratory quinone was MK-7 and the major polar lipid was phosphatidylethanolamine. On the basis of phenotypic, phylogenetic and genotypic features, strain Z12(T) is considered to represent a novel species, for which the name Dyadobacter sediminis sp. nov., is proposed. The type strain is Z12(T) ( = JCM 30073(T) = CGMCC 1.12895(T)).

Moheibacter sediminis gen. nov., sp. nov., a member of the family Flavobacteriaceae isolated from sediment, and emended descriptions of Empedobacter brevis, Wautersiella falsenii and Weeksella virosa.

A Gram-reaction-negative, yellow-pigmented, strictly aerobic bacterium, designated M0116T, was isolated from the sediment of the Mohe Basin in north-east China. Flexirubin-type pigments were produced. Cells were catalase- and oxidase-positive and non-gliding rods. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain M0116T was a member of the family Flavobacteriaceae and was most closely related to members of the genera Empedobacter, Wautersiella and Weeksella with 90.5-91.0% sequence similarities. The major cellular fatty acids were iso-C15:0 and iso-C17:0 3-OH. The major respiratory quinone was MK-6 and the major polar lipid was phosphatidylethanolamine. The DNA G+C content was 38.2 mol%. Based on phenotypic, phylogenetic and genotypic data, strain M0116T is considered to represent a novel species of a new genus in the family Flavobacteriaceae, for which the name Moheibacter sediminis gen. nov., sp. nov. is proposed. The type strain is M0116T (=CGMCC 1.12708T=JCM 19634T). Emended descriptions of Empedobacter brevis, Wautersiella falsenii and Weeksella virosa are also proposed.

Investigation of the transport and fate of Pb, Cd, Cr(VI) and As(V) in soil zones derived from moderately contaminated farmland in Northeast, China.

Some farmland in Shenyang had been irrigated with industrial wastewater since 1962. Although wastewater irrigation was ceased in 1992, soil had been heavily polluted by heavy metals, especially by Cd. For better understanding processes of soil-heavy metal interactions, in particular, the mobility and retention mechanism of heavy metal in soil, a study on the transport and fate of heavy metals in soil zones from Shenyang suburb was carried out by column leaching tests in laboratory. Breakthrough curves of Pb, Cd, Cr(VI) and As(V) fitted by Thomas model and Yoon-Nelson model. The results of fitted breakthrough curves showed that transport rates of the four heavy metals in the soil zones followed the order: Cr(VI)>As(V)>Cd>Pb, which indicated that Cr(VI) was much more mobile, and Pb was comparatively unmovable. Cr in effluents and As were almost entirely Cr(VI) and As(V), respectively, and no Cr(III) and As(III) was ever detected during the leaching tests. The contents of Pb, Cd, Cr and As in leached soils decreased in the order of Pb>Cd>Cr>As, which suggested that adsorption ability of soil to Pb was greatest and to As was least. The methods of selective sequential extraction and solvent extraction were used to determine the fractions of Pb, Cd, Cr, As and the valent states of Cr, As [Cr(VI) or Cr(III), As(V) or As(III)] in original soils and in leached soils. After leaching tests, the relative and absolute concentrations of exchangeable, carbonate, Fe-Mn oxide and organic fraction of each element were all increased, which enhanced the potential mobility and risk of Pb, Cd, Cr and As to soil/groundwater system. The relative concentrations of Cr(III) and As(III) in different depth of the soil zones after leaching tests were increased by about 6.0% and 5.6%, respectively. Cr(III) and As(III) tended to be adsorbed by soils, which reduced the mobility of them into groundwater.

Investigation of the potential mobility of Pb, Cd and Cr(VI) from moderately contaminated farmland soil to groundwater in Northeast, China.

The adsorption/desorption of Pb, Cd and Cr(VI) on moderately contaminated farmland soils in Northeast China and the effect of pH value on adsorption/desorption were investigated. Soil column leaching experiment was also carried out to further understand the mobility of the three metals in aeration zone of soil. Both Langmuir and Freundlich model gave good fits to the adsorption data of Pb and Cd, while the adsorption data of Cr(VI) followed linear adsorption isotherm. The adsorption/desorption of Pb, Cd and Cr(VI) obtained equilibrium in a few hours. Adsorption amounts of the three metals decreased in the order: Pb>Cd>>Cr(VI). Desorption of the metals was insignificant at pH 5.0. Pb and Cd adsorption increased with pH, while Cr(VI) decreased. The effect of pH on desorption was contrary to that of adsorption. Leaching experiment showed that the mobility of these metals followed the order of Cr(VI)>>Cd>Pb, which was consistent with the adsorption/desorption study. The results suggest that once soil is polluted by wastewater containing Pb and Cd, Pb and Cd tend to accumulating in topsoil and move downward very slowly, while the mobility of Cr(VI) in soil/groundwater system is much high because only limited amount of Cr(VI) were adsorbed by soil.