Identification of osteogenic differentiation-related miRNA-mRNA regulatory network of human periodontal ligament stem cells.

This study aimed to investigate the hub genes and miRNA-mRNA regulatory network around periodontal ligament stem cells (PDLSC) for osteogenic differentiation through bioinformatic analysis. The dataset with osteogenic differentiation of human PDLSC was downloaded from the GEO database. The Weighted gene coexpression network analysis (WGCNA) was performed to identify key modules and hub genes. In addition, differentially expressed genes (DEGs) analysis was conducted with limma. The functional enrichment of differentially expressed hub genes was implemented with KEGG and GSEA analysis. The targeted genes of differentially expressed miRNA were predicted based on miRWalk database. The miRNA-mRNA interaction network of osteogenic differentiation of PDLSC was constructed and visualized. The WGNCA results showed that the light-cyan module was positively correlated with osteogenic differentiation (r=0.98, P<0.05). A total of 3125 hub genes and 1426 differentially expressed hub genes were detected in OG group. Innate immune-related signaling pathways and metabolic pathways were involved in the osteogenic differentiation. In addition, total of 2 upregulated miRNAs with 63 targeted DEGs and 6 downregulated miRNAs with 214 targeted DEGs were detected, which contributed to osteogenic differentiation by regulating amino acid metabolism signaling pathway. We identified hub genes and miRNA-mRNA regulatory network contributing to osteogenic differentiation of human PDLSC, which will provide novel strategy for periodontal disease therapy.

Remediation of cadmium contaminated soil using K2FeO4 modified vinasse biochar.

The remediation of cadmium (Cd) contaminated soil is challenging for agricultural practices. In this study, a novel vinasse biochar modified by potassium ferrate (K2FeO4) was synthesized to immobilize Cd in agricultural soil. Three biochars [i.e., vinasse biochar (BC), KMnO4 modified vinasse biochar (MnBC), and K2FeO4 modified vinasse biochar (FeBC)] were applied to compare their efficiencies of Cd immobilization. The results showed that the orders of pH, ash content, and functional groups in different biochar were the same following BC < MnBC < FeBC. Scanning electron microscope images showed that the FeBC has more micropores than MnBC and BC. X-ray diffraction identified manganese oxides and iron oxides within MnBC and FeBC, indicating that Mn and Fe were well loaded on the biochar. In the soil-based pot experiment, both MnBC and FeBC significantly reduced soil available Cd by 23-38% and 36-45% compared with the control, respectively (p < 0.05). In addition, the application of BC, MnBC, and FeBC significantly increased the yield, chlorophyll, and vitamin C of Chinese cabbage (p < 0.05), and decreased its Cd uptake compared with the control. Notably, shoot Cd significantly reduced when 2% FeBC was applied (p < 0.05). Overall, using K2FeO4 to modify vinasse biochar enriched the surface functional groups and minerals as well as reduced Cd availability in soil and its uptake by the plant. Our study showed that K2FeO4 modified vinasse biochar could be used as an ideal amendment for the remediation of Cd-contaminated soil.

Enhanced silicate remediation in cadmium-contaminated alkaline soil: Amorphous structure improves adsorption performance.

Silicates have been used as soil heavy metal passivators, but low remediation efficiency limited their development. In order to solve this problem, in this paper, an economical and environmentally friendly amorphous iron silicate was prepared by a simple co-precipitation method. It could be proved from the passivation experiments that the remediation efficiency of amorphous iron silicate (AIS) on Cd-contaminated soil was better than that of natural silicates (montmorillonite and diatomite), which reflected the superiority of amorphous materials. Plant experiments showed that AIS could effectively inhibit the absorption and accumulation of Cd2+ in the edible parts of garlic. In addition, it may effectively reduce the potential ecological risk assessment of soil, and its immobilization mechanism of Cd2+ includes electrostatic adsorption, co-precipitation, ion exchange, and complexation of surface functional groups. This study demonstrates the advantages of amorphous iron silicate as a new functional material in the remediation of Cd-contaminated soil and provides a reference for the development and application of environment-friendly passivators.

Adsorption of Cu2+ by UV aged polystyrene in aqueous solution.

Microplastics are the critical carriers of heavy metals in the environment. Thus, investigating the adsorption mechanisms between the microplastics and heavy metals is helpful to understand the migration and transformation pattern of the heavy metals in the environment. The adsorption of microplastics towards heavy metals can be largely affected by natural aging (e.g., UV-aging), environmental pH, and salinity. In this study, the adsorption of polystyrene (PS) towards Cu2+ and the effects of UV-aging, environment pH, and salinity on the adsorption were systematically investigated. The results show that the adsorption capacity of PS towards Cu2+ increased with the UV-aging time, as UV-aging increased the microcracks and oxygen-containing functional groups on the surface of the PS. Adsorption kinetics data followed the pseudo-second-order model, indicating that the interaction between PS and Cu2+ is chemical adsorption. Adsorption isotherms data could be well-described by both the Langmuir and Freundlich models, indicating that the adsorption was multilayer adsorption. As the solution pH and salinity can influence the surface charge of the PS, they could also affect the performance of the PS on Cu2+ adsorption. High pH facilitated the adsorption of PS towards Cu2+, while high salinity (above 1‰) inhibited the adsorption.

Response of microbiomes with different abundances to removal of metal fractions by soil washing.

Toxic metal contamination causes a great threat to soil ecosystem and human health. Soil washing is a fast practice for removing metals, but its influences on microbial diversity and the stability of soil ecosystem remain unknown. In this study, ethylenediaminetetraacetic acid (EDTA), citric acid (CA), and fermented pineapple peel residue (FPP) were used as representatives of chelates, low molecular organic acids and biological materials to wash Pb-polluted soils, and their impacts on microbial community were investigated. Washing with these agents effectively removed Pb, but altered microbial community structure. After washing with EDTA, CA, and FPP, 3-8 bacterial phyla and 1 fungal phylum greatly increased, while 7-20 bacterial and 0-6 fungal phyla severely decreased or even disappeared. The alterations of different microbiomes were closely related to soil metal fractions. The labile metal fraction had negative effects on most bacteria and fungi, but also showed positive influences on Actinobacteria, Patescibacteria, and Fusobacteria. The moderately stable and stable fractions were nontoxic to the most microbes, but still harmful to Patescibacteria and Deinococcus-Thermus. These findings provide new insights for the effects of soil washing remediation and toxicity of metal fractions on the microbiomes with different abundance.

Dynamics of sediment phosphorus affected by mobile aeration: Pilot-scale simulation study in a hypereutrophic pond.

Controlling the release of phosphorus (P) in sediments is important to prevent eutrophication and harmful algal blooms in water bodies. Here we explored the effect of mobile aerators on the control of P release from sediments in a eutrophic pond. The dissolved oxygen in the water body recovered significantly after six months of aeration, becoming 4.2-5.8 times higher than in the control. The pH and Eh values at the sediment-water interface considerably increased, while the concentration of soluble reactive phosphorus (SRP) in pore water significantly decreased, resulting in the alteration of SRP fluxes from 1.69 mg/m2 d to -53.49 mg/m2 d. Moreover, the inert P in sediments increased by 5.2% of the total P at the end of the study compared with the initial state, and the calcium-bound phosphorus (HCl-P) increased by 96.6%. However, although aeration reduced the concentration of SRP in the water column, the total P concentration was 2.45 times higher than that of the control, and the content of redox-sensitive P (BD-P) in the sediment also increased by 200%. Overall, although mobile aeration can maintain the microenvironment of the sediment interface and increase the inert P content in the sediment to reduce the P flux, it cannot reduce the risk of release of mobile P.

Mechanism and ecological environmental risk assessment of peroxymonosulfate for the treatment of heavy metals in soil.

Oxidation technologies based on peroxymonosulfate (PMS) have been effectively used for the remediation of soil organic pollutants due to their high efficiency. However, the effects of advanced PMS-based oxidation technologies on other soil pollutants, such as heavy metals, remain unknown. In this study, changes in the form of heavy metals in soil after using PMS and the risk of pollution to the ecological environment were investigated. Furthermore, two risk assessment methods, the mung bean germination toxicity test and groundwater leaching soil column test, were employed to evaluate the soil before and after PMS treatment. The results showed that PMS has a strong ability to degrade complex compounds, enabling the transformation of heavy metals, such as Cd, Pb, and Zn, from stable to active states in the soil. The risk assessments showed that PMS treatment activated heavy metals in the soil, which delayed the growth of plants, increased heavy metal content in plant tissues and the risk of groundwater pollution. These findings provide a new perspective for understanding the effects of PMS on soil, thus facilitating the sustained and reliable development of future research in the field of advanced oxidation applied to soil treatment.

Biochar-derived dissolved organic matter enhanced the release of residual ciprofloxacin from the soil solid phase.

Biochar has been utilized to reduce ciprofloxacin (CIP) residues in soil. However, little is known about the effect of biochar-derived dissolved organic matter (DOM) on residual CIP transformation. Thus, we analyzed the residual soil CIP as influenced by biochar generated from rice straw (RS3 and RS6), pig manure (PM3 and PM6), and cockroach shell (CS3 and CS6) at 300 °C and 600 °C. The three-dimensional excitation-emission matrix (3D-EEM), parallel factor analysis (PARAFAC) and two-dimensional correlation spectral analysis (2D-COS) were used to describe the potential variation in the DOM-CIP interaction. Compared with CK, biochar amendment increased the water-soluble CIP content by 160.7% (RS3), 55.2% (RS6), 534.1% (PM3), 277.5% (PM6), 1160.6% (CS3) and 703.9% (CS6), indicating that the biochar feedstock controlled the soil CIP release. The content of water-soluble CIP was positively correlated with the content of dissolved organic carbon (r = 0.922, p < 0.01) and dissolved organic nitrogen (r = 0.898, p < 0.01), suggesting that the major influence of the water-soluble CIP increase was DOM. The fluorescence quenching experiment showed that the interaction between DOM and CIP triggered static quenching and the creation of a DOM complex. The mean log K of protein-like material (4.977) was higher than that of terrestrial humus-like material (3.491), suggesting that the protein-like material complexed CIP was more stable than the humus-like material. Compared with pyrolysis at 300 °C, pyrolysis at 600 °C decreased the stability of the complex of protein-like material and CIP by 0.44 (RS), 1.689 (PM) and 0.548 (CS). This result suggested that the influence of temperature change was more profound on PM biochar-derived DOM than on RS and CS. These insights are essential for understanding CIP transportation in soil and controlling CIP contamination with biochar.

Inhibition of high sulfur on functional microorganisms and genes in slightly contaminated soil by cadmium and chromium.

It is generally accepted that sulfur can passivate the bioavailability of heavy metals in soil, but it is not clear whether high sulfur in cadmium (Cd) and chromium (Cr) contaminated soil has negative effect on soil microbial community and ecological function. In this study, total sulfur (TS) inhibited the Chao 1, Shannon, Phylogenetic diversity (Pd) of bacterial and Pd of fungi in slightly contaminated soil by Cd and Cr around pyrite. TS, total potassium, pH, total chromium, total cadmium, total nitrogen, soil organic matter were the predominant factors for soil microbial community; the contribution of TS in shaping bacterial and fungal communities ranked at first and fifth, respectively. Compared with the low sulfur group, the abundance of sulfur sensitive microorganisms Gemmatimonas, Pseudolabrys, MND1, and Schizothecium were decreased by 68.79-97.22% (p < 0.01) at high sulfur one; the carbon fixation, nitrogen cycling, phosphorus cycling and resistance genes abundance were significantly lower (p < 0.01) at the latter. Such variations were strongly and closely correlated to the suppression of energy metabolism (M00009, M00011, M00086) and carbon fixation (M00173, M00376) functional module genes abundance in the high sulfur group. Collectively, high sulfur significantly suppressed the abundances of functional microorganisms and functional genes in slightly contaminated soil with Cd and Cr, possibly through inhibition of energy metabolism and carbon fixation of functional microorganisms. This study provided new insights into the environmental behavior of sulfur in slightly contaminated soil with Cd and Cr.

Effects of climate and geochemical properties on the chemical forms of soil Cd, Pb and Cr along a more than 4000 km transect.

Soil heavy metal speciation has received much attention for their different ecological and environmental effects. However, the effects of climate and soil geochemical properties on them in uncontaminated soils at macroscale were still unclear. Therefore, a transect more than 4000 km was chosen to study the effects of these factors on soil Cd, Pb and Cr forms. The results revealed that mean annual temperature and precipitation showed significant positive relations with the exchangeable and Fe-Mn oxide bound states of Cd, Pb and Cr, and residual Cr. And humidity and drought indexes were significantly positively correlated with their organic and carbonate bound forms, respectively. As for soil geochemical properties, pH displayed significant negative relationships with exchangeable, Fe-Mn oxide and organic bound Pb and Cr, and exchangeable Cd. Fe2O3 was significantly positively with the exchangeable and Fe-Mn oxide bound Cd, Pb and Cr, and residual Cr. And soil organic matter showed positive relations with organic bound Pb and Cr, and residual Cd and Cr, displayed negative relationships with carbonated bound Pb and Cr. Overall, climate and soil geochemical properties together affect the transformation and transport of heavy metals between different forms in uncontaminated soils.

miR-137 restoration sensitizes multidrug-resistant MCF-7/ADM cells to anticancer agents by targeting YB-1.

Multidrug resistance (MDR) to chemotherapeutic agents is a major obstacle to successful treatment in breast cancer patients. The aims of this study were to investigate whether miR-137 was involved in the regulation of MDR, and to explore the mechanism of miR-137 on the sensitivity of MCF-7/ADM cells. miR-137 was downregulated in MCF-7/ADM cells, and its expression was found to inversely correlate with Y-box binding protein-1 (YB-1) and P-glycoprotein (P-gp) levels in breast cancer cells. Furthermore, YB-1 was confirmed as a target of miR-137 by luciferase reporter assay and western blot analysis. Moreover, elevated expression of miR-137 reduced the protein expression levels of YB-1 and P-gp, mimicking the effect of YB-1 knockdown in the sensitivity of MCF-7/ADM cells to anticancer agents, whereas restoration of YB-1 diminished this effect. In conclusion, our results demonstrated that miR-137 was involved in MDR in cancer through modulation of P-gp by targeting YB-1, suggesting that miR-137 might be a potential target for preventing and reversing MDR in tumor cells.

miR-106a confers cisplatin resistance by regulating PTEN/Akt pathway in gastric cancer cells.

Recent studies have shown that microRNA-106a (miR-106a) is overexpressed in gastric cancer and contributes to tumor growth. In this study, we investigated whether miR-106a mediated resistance of the gastric cancer cell line SGC7901 to the chemotherapeutic agent cisplatin (DDP). MiR-106a expression was up-regulated in the DDP resistant cell line SGC7901/DDP compared with its parental line SGC7901. Transfection of miR-106a induced DDP resistance in SGC7901, while suppression of miR-106a in SGC7901/DDP led to enhanced DDP cytotoxicity. Further study indicated that the mechanism of miR-106a-induced DDP resistance involved the expression of phosphatase and tensin homolog deleted from chromosome 10 (PTEN) protein and its downstream phosphatidylinositol 3 kinase (PI3K)/protein kinase B (AKT) pathway. This study provides a novel mechanism of DDP resistance in gastric cancer.

Promotional effects of Nb5+ and Fe3+ co-doping on catalytic performance and SO2 resistance of MnOx-CeO2 low-temperature denitration catalyst.

As we know, SO2 can cause MnOx-CeO2 (MnCeOx) catalyst poisoning, which seriously shortens the service life of the catalyst. Therefore, to enhance the catalytic activity and SO2 tolerance of MnCeOx catalyst, we modified it by Nb5+ and Fe3+ co-doping. And the physical and chemical properties were characterized. These results illustrate that the Nb5+ and Fe3+ co-doping can optimally improve the denitration activity and N2 selectivity of MnCeOx catalyst at low temperature by improving its surface acidity, surface adsorbed oxygen as well as electronic interaction. What's more, NbOx-FeOx-MnOx-CeO2 (NbFeMnCeOx) catalyst possesses an excellent SO2 resistance due to less SO2 being adsorbed and the ammonium bisulfate (ABS) formed on its surface tends to decompose, as well as fewer sulfate species formed on its surface. Finally, the possible mechanism that Nb5+ and Fe3+ co-doping enhances the SO2 poisoning resistance of MnCeOx catalyst is proposed.

Effects of intercropping ryegrass with hollyhock and inoculation with Bacillus thuringiensis on enhancing phytoremediation of Cd-contaminated soils.

Cd is a heavy metal that contaminates soils. These kinds of heavy metals pose a serious threat to food security, ecosystems, and human health. To improve the phytoremediation efficiency of moderately Cd-contaminated cropland soils and achieve simultaneous production and remediation, intercropping ryegrass (Lolium perenne L.) with hollyhock (Althaea rosea) was investigated using pot experiments, and Bacillus thuringiensis (B. thuringiensis) inoculation was used as a booster to strengthen the absorption and accumulation of Cd in plants. The results showed that intercropping (Int treatment) decreased the Cd concentration in plants compared to hollyhock and ryegrass monocropping. However, the Cd accumulation in ryegrass and hollyhock was promoted by B. thuringiensis addition to intercropping (Int-B treatment), as the biomass of ryegrass and hollyhock was 2.33 and 1.13 times that of the Int treatment, respectively. Compared with the Int treatment, the total Cd concentration in soils of the Int-B treatment decreased by 8.1%, while diethylenetriaminepentaacetic acid solution extracted Cd (DTPA-Cd) increased by 18.2%, indicating that B. thuringiensis increases the available Cd concentration in soils to promote Cd adsorption by hollyhock enrichment plants. High-throughput sequencing results further revealed that the dominant microflora in the soils of the Int and Int-B treatments were consistent with the control, although their abundance and diversity decreased slightly. Overall, intercropping with B. thuringiensis addition effectively increased the hollyhock remediation efficiency in moderately Cd-contaminated soils, and the concentration of Cd in forage crops of ryegrass was lower than the limit value of "Hygienic standards for feeds' (GB 13078-2017) in China.

Effects of variable-sized polyethylene microplastics on soil chemical properties and functions and microbial communities in purple soil.

Microplastic contamination of soil has drawn increased attention due to the ecological harm it poses to the soil ecosystem. However, little is known about how microplastic particle sizes affect soil chemical properties and microbial communities, particularly in purple soil. In this study, a four-week incubation experiment was conducted to evaluate the effect of polyethylene microplastics (PE MPs) with different particle sizes (i.e., 300 and 600 µm) on soil properties, extracellular polymeric substances (EPS), enzyme activities, and microbial communities in purple soil. When compared to 600 µm-PE MPs, 300 µm-PE MPs reduced contents of dissolved organic matter (DOM), EPS, and ß-1,4-N-acetylglucosaminidase (NAG) activity, but increased the cation exchange capacity (CEC). High-throughput 16S rRNA gene sequencing revealed that the 300 µm-PE MPs resulted in an increase in the phylum Nitrospirae, which is associated with microplastic degradation. The data implied that smaller PE MPs improved the growth of polyethylene-degrading bacteria by adsorbing more EPS and DOM, resulting in the degradation of microplastics. Co-occurrence network analysis revealed that smaller PE MPs had lower toxicity to microbial populations than larger PE MPs, increasing the stability of the network. CEC and ß-1,4-glucosidase (BG) were found to be the two major factors affecting the microbial communities by redundancy analysis (RDA). The study highlighted how microplastic particle sizes affect soil bacterial communities and soil functions.

Effects of overwintering cyanobacteria on phosphorus and iron regeneration across the sediment-water interface: A pilot simulation experiment.

Cyanobacterial blooms are a major environmental problem in eutrophic reservoirs in China. Algal cells can migrate to the sediment surface in winter and maintain biological activity, which could further affect the cycling process of sediment phosphorus (P) and iron (Fe). In this study, a pilot simulation experiment was conducted to investigate the effect of overwintering cyanobacteria (Owc) on P and Fe regeneration across the sediment-water interface (SWI). Owc esterase activity ranged from 16.4 to 26.6 nmol (FDA)/(L·h), with a fluctuating increasing trend within the incubation time. Compared with the control (no Owc), Owc treatment increased the redox potential value (Eh) at the SWI but slightly decreased the pH during the first stage of this experiment (0-24 d); however, the Eh at the SWI under Owc treatment decreased to 50.9 % of that of the control on day 90. The Fe(II) could rapidly oxidized to Fe (oxyhydro)oxides and combine with phosphate in high Eh environments, and Owc inhibited P and Fe release at the SWI within 24 days; however, the continuous decrease in Eh resulted in the reduction of Fe(III). Thus, the Fe concentration measured via diffusive gradients in thin films in the Owc-treated interstitial water gradually increased to 1.92 times that of the control, promoting the release of Fe and P across the SWI. For 13 days after Owc addition, the amount of mobile P in the sediment was significantly higher than that in the control, and it gradually decreased from day 24 to 90, with the lowest being approximately 74.1 % of the amount in the control. The reactive Fe concentration in the sediment showed a similar variation trend. These results indicate that mobile P and reactive Fe in the sediment could be the main sources of regeneration across the SWI in the presence of Owc.

Improvement of cadmium immobilization in contaminated paddy soil by using ureolytic bacteria and rice straw.

Cadmium (Cd) in paddy soil can be immobilized via microbially induced carbonate precipitation (MICP), but it poses a risk to the properties and eco-function of the soil. In this study, rice straw coupled with Sporosarcina pasteurii (S. pasteurii) was used to treat Cd-contaminated paddy soil with minimizing the detrimental effects of MICP. Results showed that the application of rice straw coupled with S. pasteurii reduced Cd bioavailability. The X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) confirmed that Cd immobilization efficiency was increased in the rice straw coupled with S. pasteurii treatment via co-precipitating with CaCO3. Moreover, rice straw coupled with S. pasteurii enhanced soil fertility and ecological functions as reflected by the high amount of alkaline hydrolysis nitrogen (AN) (14.9 %), available phosphorus (AP) (13.6 %), available potassium (AK) (60.0 %), catalase (9.95 %), dehydrogenase (736 %), and phosphatase (214 %). Further, the relative abundance of dominant phyla such as Proteobacteria and Firmicutes significantly increased when applying both rice straw coupled with S. pasteurii. The most significant environmental factors that affected the composition of the bacterial community were AP (41.2 %), phosphatase (34.2 %), and AK (8.60 %). In conclusion, using rice straw mixed with S. pasteurii is a promising application to treat Cd-contaminated paddy soil due to its positive effects on treating soil Cd as well as its ability to reduce the detrimental effects of the MICP process.

Effects of complex pollution by microplastics and heavy metals on soil physicochemical properties and microbial communities under alternate wetting and drying conditions.

Microplastics (MPs) broadly coexist with heavy metals (HMs) in soil, Cd and Cu are the main types of soil HMs contamination, in addition to polystyrene (PS), which is also widely present in the environment and prone to aging. However, differences in the effects of MPs and HMs on soil properties and microbial characteristics under alternating wetting and drying (AWD) remain unclear. Thus, this study investigated the effects of four conventional (0.2% (w/w)) and aged MPs in indoor incubation experiments on soil properties under desiccation (Dry) and AWD. We found that with the influence of the "enzyme lock" theory, the coexistence of MPs and HMs under Dry had a more pronounced effect on soil physicochemical properties, whereas the effects on soil enzyme activity under AWD were more significant. In addition, MPs decreased the available Cu by 4.27% and, conversely, increased the available Cd by 8.55%. Under Dry, MPs affected microbial function mainly through physicochemical properties, with a contribution of approximately 72.4%, whereas under AWD enzyme activity and HMs were significantly greater, with increases of 28.2% and 7.9%, respectively. These results indicate that the effects of MPs on environmental variation and microbial profiles under AWD conditions differed significantly from those under Dry.

Allelopathic effect of pyrogallic acid on cyanobacterium Microcystis aeruginosa: The regulatory role of nitric oxide and its significance for controlling harmful algal blooms (HABs).

Utilization of allelochemicals to inhibit overgrowth of toxic cyanobacteria is considered to be an environmentally friendly approach. However, the regulatory role of the signaling molecule nitric oxide (NO) on cyanobacteria under allelopathic stress remains unanswered. Here we demonstrate that the effect of NO on the cyanobacterium Microcystis aeruginosa depends on allelopathic stress of pyrogallic acid (PA). The experimental results revealed that general stimulation of M. aeruginosa by PA occurred within the concentration range 0.4-0.8 mg/L. In parallel with increasing concentration of PA (1.6-16.0 mg/L), the growth of M. aeruginosa was observed to decrease. The effect of NO on M. aeruginosa was evaluated by addition of the NO scavenger hemoglobin. In the stimulation stage, intracellular NO was seen to decreased to modulate the level of reactive oxygen species (ROS) and to maintain redox homeostasis of the cells. In the inhibition stage, the physiological characteristics of M. aeruginosa were changed significantly. Additionally, the accumulation of S-nitrosothiol by M. aeruginosa indicated that the high concentrations of PA induced nitric oxidative stress in M. aeruginosa. This study provides a new thought to understand the role of NO in controlling harmful algal blooms through the allelopathic effect of aquatic macrophytes.

A novel bio-washing eluent obtained from fermentation of fruit wastes for removal of soil Pb: efficiency, mechanism, and risk assessment.

Agricultural wastes are inexpensive materials for soil remediation. However, the direct water extracts from these wastes showed low efficiency for Pb removal, thus limiting their application. In this study, citrus pericarp (CP) and pineapple peel (PP), as the common agricultural wastes, were inoculated with lactic acid bacteria to produce fermentation liquors (FCP and FPP) for improving Pb removal efficiency. Results showed that the Pb removal rates by FCP and FPP reached 37.3 and 43.6%, and increased by almost 50.0% than those by CP and PP. The ecological risk of Pb reduced by 83.0-88.2% after five times continuous washing with FCP and FPP, and the Pb concentrations conformed to soil remediation standard of China. Moreover, soil organic carbon 1.5 times increased in the washed soils, while total potassium improved by 40.7-68.0%. The mechanisms of Pb removal by these wastes involved in adsorption-desorption of Pb2+, complexation with organic ligands, and co-precipitation of Pb complexes. The increase of low molecular organic acids during the fermentation promoted dissolution of Pb and provided more hydroxyl, carboxyl, and amine groups to interact with Pb2+, thus improving its removal rate. Therefore, fermentation liquid from fruit wastes is a novel, effective, and ecofriendly bio-washing eluent for Pb removal from contaminated soils.