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Hydrogen sulfide (H2S), an emerging gas transmitter, has been shown to be involved in multiple intracellular physiological and biochemical processes. In this study, the effects of hydrogen sulfide coupled with calcium on cadmium removal and resistance in Phanerochaete chrysosporium were examined. The results revealed that H2S enhanced the uptake of calcium by P. chrysosporium to resist cadmium stress. The removal and accumulation of cadmium by the mycelium was reduced by H2S and Ca2+ pretreatment. Moreover, oxidative damage and membrane integrity were alleviated by H2S and Ca2+. Corresponding antioxidative enzyme activities and glutathione were also found to positively respond to H2S and Ca2+, which played an important role in the resistance to cadmium-induced oxidative stress. The effects of hydroxylamine (HA; a hydrogen sulfide inhibitor) and ethylene glycol-bis-(2-aminoethylether)-N,N,N′,N′-tetraacetic acid (EGTA; a calcium chelator) toward H2S and Ca2+ and their cross-interactions confirmed the positive roles and the potential crosstalk of H2S and Ca2+ in cadmium stress resistance. These findings imply that the protective effects of H2S in P. chrysosporium under cadmium stress may occur through a reduction in the accumulation of cadmium and promotion of the antioxidant system, and the H2S-regulated pathway may be associated with the intracellular calcium signaling system. Key points • Altered monoterpenoid tolerance mainly related to altered activity of efflux pumps. • Increased tolerance to geranic acid surprisingly caused by decreased export activity. • Reduction of export activity can be beneficial for biotechnological conversions. [ABSTRACT FROM AUTHOR]

[Display omitted] • P. chrysosporium could tolerate IMI and transform 93.5% for 6 days. • Manganese and lignin peroxidase played important roles in IMI transformation. • IMI mainly underwent nitrate-reduction, hydroxylation, and de-chlorination process. • MD results explained the reactive sites and metabolic mechanisms of enzymes. • 6-chloronicotinic acid, a less neurologically toxic major metabolite, was detected. As one of the widely used neonicotinoid insecticide, imidacloprid (IMI) poses serious threat on many kinds of non-target species. The acceleration of its removal from the contaminated environment is therefore an urgent task. Herein, the transformation of IMI by white-rot fungus Phanerochaete chrysosporium was examined, and the reaction mechanism underlying enzymes-mediated IMI biotransformation was elucidated. In addition, transformed products, pathways, and toxicity to Escherichia coli and Microcystis aeruginosa or the growth of rice seeds were investigated. P. chrysosporium could efficiently transform 93.5% of IMI for 6 days primarily through biotransformation, in which extracellular manganese peroxidase and lignin peroxidase substantially responded to transform IMI. IMI mainly underwent nitrate reduction, hydroxylation, and de-chlorination. A less neurologically toxic major metabolite of IMI, 6-chloronicotinic acid, was detected. Molecular dynamics simulation demonstrated that IMI stably bonded to active pocket of extracellular enzymes. This study reveals the key metabolic mechanism and fate of IMI in environment, and highlights the potential of fungi for IMI transformation. [ABSTRACT FROM AUTHOR]

Due to the widespread application of white-rot fungi for the treatment of pollutants, it's crucial to exploit the special effects of pollutants on the microbes. Here, we studied the effects of cadmium on calcium homeostasis in the most studied white-rot fungus Phanerochaete chrysosporium . The response of P. chrysosporium to cadmium stress is concentration-dependent. A high concentration of cadmium caused the release of calcium from P. chrysosporium , while a hormesis effect was observed at a lower cadmium concentration (10 μM), which resulted in a significant increase in calcium uptake and reversed the decrease in cell viability. Calcium (50 μM) promoted cell viability (127.2% of control), which reflects that calcium can protect P. chrysosporium from environmental stress. Real-time changes in the Ca 2+ and Cd 2+ fluxes of P. chrysosporium were quantified using the noninvasive microtest technique. Ca 2+ influx decreased significantly under cadmium exposure, and the Ca 2+ channel was involved in Ca 2+ and Cd 2+ influx. The cadmium and/or calcium uptake results coupled with the real-time Ca 2+ and Cd 2+ influxes microscale signatures can enhance our knowledge of the homeostasis of P. chrysosporium with respect to cadmium stress, which may provide useful information for improving the bioremediation process. [ABSTRACT FROM AUTHOR]

Imidacloprid (IMI), a typic neonicotinoid insecticide, is widely used and persist in soils with long half-time causing serious threat to ecosystem and human health. It is urgent to develop suitable and effective methods to accelerate it degradation and alleviate its negative impacts in soil. In this study, the introduction of functional microbe white-rot fungus Phanerochaete chrysosporium to remediate IMI contaminated wetland soil was carried out. The remediation performance and the response of the soil microbial community were examined. The results showed that P. chrysosporium could improve the degradation of IMI in soil no matter the soil was sterilized or not. The bioaugmentation was especially observed in non-sterilized soil under the inoculation patterns of FE and SP with the maximum IMI degradation rate of 91% and 93% in 7 days, respectively. The invertase activity in soil was also enhanced with P. chrysosporium inoculation. Microbial community analysis revealed that P. chrysosporium inoculation could increase the diversity and richness of bacterial community, and stimulate some IMI degraders genera including Ochrobactrum , Leifsonia , Achromobacter , and Bacillus. Moreover, the xenobiotic degradation and metabolism pathway was generally enhanced with P. chrysosporium inoculation based on PICRUSt analysis. These obtained results demonstrated that the introduction of white-rot fungus is of great potentially enabling the remediation of neonicotinoids contaminated soil. [Display omitted] • P. chrysosporium improved and accelerated IMI degradation in wetland soil. • Inoculation pattern affects IMI degradation and microbial community differently. • The invertase activity in soil was enhanced with P. chrysosporium inoculation. • P. chrysosporium increased microbial diversity, richness, and IMI degraders. • Xenobiotic degradation and metabolism pathway was enhanced during the remediation. [ABSTRACT FROM AUTHOR]

The extensively used neonicotinoid pesticides are reported seriously threatened ecological environment and even human health, which is one of the most urgent environmental problems. In this study, the bioremediation of thiamethoxam contaminated wetland soil by Phanerochaete chrysosporium and the analysis of microorganisms' response was conducted. Results showed that P. chrysosporium improved thiamethoxam degradation both in non-sterilized and sterilized soils. Obvious bioaugmentation of thiamethoxam degradation was especially found in non-sterilized soil at the earlier stage (< 10 d). The pH of the soils increased accompanied with the decreasing in organic matter after remediation. Increase in invertase activity and decrease in urease activity was observed, while the catalase activity changed little. Microbial community analysis illustrated that phyla Proteobacteria , Actinobacteria , Firmicutes , and Bacteroidetes were the dominate species for bacteria, and phyla Ascomycota , Basidiomycota were the dominate species for fungi. P. chrysosporium inoculation in different modes shifted the composition and relative abundance of microbial community differently, but increased in microbial diversity in soil was observed overall. The obtained results proved that white-rot fungus P. chrysosporium enhanced elimination was available for bioremediation of thiamethoxam contaminated soil. [Display omitted] • P. chrysosporium enhanced remediation of THX contaminated soil was confirmed. • THX degradation, soil enzymes, and microbial community varied with inoculated modes. • Increased microbial diversity overall with P. chrysosporium inoculation. [ABSTRACT FROM AUTHOR]

The extracellular secretions are believed to have a significant influence on microorganisms physicochemical properties related to growth, morphological preservation, and environment stress defense. In this study, the response and potential detoxification role of the extracellular secretions in the widely used white-rot fungus, Phanerochaete chrysosporium , was investigated. The results indicated that the EPS production was elevated and the activities of two main ligninolytic enzymes (LiP and MnP) were generally inhibited by cadmium. At the early exposure period (0–8 h), the extracellular protein was induced by 50 μM cadmium. However, an opposite result was observed with further increase in exposure time. The oxalate secretion under cadmium stress increased by 73.2%–218.4% compared to control. The addition of oxalic acid resulted in elevation in P. chrysosporium viability up to 190.6%, which confirms the detoxification of oxalate. The extracellular secretions such as EPS, extracellular protein and oxalate were elevated in some extent by cadmium, which was probably a stress response for P. chrysosporium to bind cadmium ion and cope the toxicity. Moreover, extracellular biosynthesis of cadmium crystal particles was observed, which is a directly evidence of P. chrysosporium extracellular secretions to reduce the mobility and bioavailability of cadmium ion. [ABSTRACT FROM AUTHOR]

Microorganisms need to resist the hazards posed by heavy metals during the process of metal adsorption. Phanerochaete chrysosporium is a fungus that is efficiently used for heavy-metal biosorption in wastewater treatment. Extraction and analysis of proteins induced by heavy metals can help to understand the regulatory mechanisms of P. chrysosporium in wastewater treatment. In this study, P. chrysosporium was exposed to 50 μM cadmium nitrate. A maximum cadmium adsorption capability of 77.1 mg/g dry biomass was found after 65 h, which was accompanied by a relatively higher protein concentration. After separation of the culture fluid proteins by two-dimensional difference gel electrophoresis (2D-DIGE), three differentially expressed proteins were detected from 17 spots. By using 2D-DIGE, followed by matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry (MALDI-TOF/TOF MS), glutathione S-transferase, glyceraldehyde-3-phosphate dehydrogenase, and malate dehydrogenase were identified. All three enzymes play important roles in the oxidative stress caused by cadmium. [ABSTRACT FROM AUTHOR]

Highlights: [•] H2S alleviated 2,4-DCP toxicity and improved its degradation by P. chrysosporium. [•] H2S shortened the time required for 2,4-DCP complete degradation. [•] H2S alleviated 2,4-DCP caused oxidative stress and improved cell viability. [Copyright &y& Elsevier]

Highlights: [•] Membrane fluidity and H+-ATPase activity were significantly reduced by cadmium. [•] Cadmium induced cell death is produced by breakdown of MMP and ROS formation. [•] Extracellular cadmium crystal particles were synthesized after exposure to Cd2+. [•] Cells survive by activating antioxidant and biosynthesis of crystal particles. [Copyright &y& Elsevier]

The extensive use of neonicotinoid pesticides in the past two decades caused serious impacts on many kinds of living beings. Therefore, it has been strongly suggested to detoxify and eliminate neonicotinoids' residual levels in environment. Here, the degradation and detoxification of thiamethoxam (THX) by white-rot fungus Phanerochaete chrysosporium was conducted. Results shown that P. chrysosporium can tolerate THX and degraded 49% of THX after incubation for 15 days, and then 98% for 25 days at the initial concentration of 10 mg/L, which indicates the excellent degradation ability of this fungus to THX. Based on the by-products identified, THX underwent dechlorination, nitrate reduction, and C–N cleavage between the 2-chlorothiazole ring and oxadiazine. (Z)-N-(3-methyl-1,3,5-oxadiazinan-4-ylidene)nitramide and 3-methyl-1,3,5-oxadiazinan-4-imine were identified as the main metabolites. The impacts of THX and its corresponding degradation intermediates on the growth of E. coil and Microcystis aeruginosa as well as the germination of rape and cabbage demonstrated that P. chrysosporium effectively degrades THX into metabolites and reduces its biotoxicity. The present work demonstrates that P. chrysosporium can be effectively used for degradation and detoxification of THX. [Display omitted] • Phanerochaete chrysosporium showed excellent degradation ability to THX. • Five transformation products were identified during biodegradation of THX. • Dichlorination, nitrate reduction, and cleavage of C–N were the major decomposition route. • The THX metabolites showed less biotoxicity. [ABSTRACT FROM AUTHOR]

This study systematically investigated the advanced oxidation processes driven by the white-rot fungus (WRF) Phanerochaete chrysosporium in the removal of the neonicotinoid pesticide imidacloprid (IMI). The quinone redox cycling driven by P. chrysosporium promotes the degradation of IMI in presence of Mn2+ and Fe (III)-oxalate. Results showed that the degradation efficiency varied with the type of quinine mediator, and gallic acid (GA) was a more effective mediator than 1,4-benzoquinone (BQ). The removal rate of IMI was increased by 1.8-fold in the presence of 100 μM of Mn2+ compared with that of the system without Mn2+. The addition of oxalic acid and EDTA promoted the degradation of IMI, and the effect of oxalic acid was more pronounced at the later stage (day 5 and day 6); the optimal Fe3+/oxalate ratio was 1:3. Time-course experiments revealed the maximum removal rates of IMI were 97.37%, 82.0% and 73.52% at the initial IMI concentration of 10, 20, and 30 mg/L, respectively, in the presence of 100 μM Mn2+, 100 μM Fe3+-300 μM of oxalate and 500 μM gallic acid. Under quinone redox cycling conditions, the good correlation between ·OH production rates and the enzymes activity was concluded, the quinines redox cycles promote enzyme activity, as well as the rate of ·OH production. Results from this study indicated the GA mediator-based system using P. chrysosporium offers a new method to advance the bio-oxidation process owing to its simple culture system, low-cost precursors, unique fungi, and degradation stability. • P. chrysosporium has the ability to drive advanced oxidation processes. • Advanced bio-oxidation by P. chrysosporium increased its degradation ability. • An appropriate amount of Mn2+ is beneficial for IMI degradation. • The substitution of Fe3+-EDTA by Fe3+-oxalate improve IMI degradation rate. • The quinines redox cycles promote enzyme activity. [ABSTRACT FROM AUTHOR]

Abstract Hydrogen sulfide (H 2 S), an important cellular signaling molecule, plays vital roles in mediating responses to biotic/abiotic stresses. Influences of H 2 S on metal removal, cell viability, and antioxidant response of Phanerochaete chrysosporium upon exposure to heavy metals and silver nanoparticles (AgNPs) in the present study were investigated. An enhancement in Pb(ΙΙ) removal with an increase in concentration of the H 2 S donor sodium hydrosulfide (NaHS) was observed, and the maximum removal efficiencies increased by 31% and 17% under 100 and 200 mg/L Pb(ΙΙ) exposure, respectively, in the presence of 500 μM NaHS. Application of 500 μM NaHS increased the cell viability by 15%–39% under Pb(II) stress (10–200 mg/L) with relative to the untreated control. Increase in total Ag uptake and cell survival was also elicited by NaHS in a concentration-dependent manner under AgNP stress. Meanwhile, activities of superoxide dismutase and catalase were significantly enhanced with the introduction of NaHS under stresses of Pb(II), Cd(II), Cu(II), Zn(II), Ni(II), and AgNPs. The inhibition in lipid peroxidation and oxidative stress was observed in P. chrysosporium cells exposed to these toxicants following NaHS pretreatment, which could be attributed to the upregulation in antioxidant enzymes. The results obtained suggest that H 2 S can alleviate heavy metals and AgNP-induced toxicity to P. chrysosporium and improve the removal efficiency of these toxicants from wastewater. Highlights • H 2 S can greatly improve the removal of metal ions and total Ag from wastewater. • A dose-dependent increase in cell survival was evoked by H 2 S under toxicant stress. • Application of H 2 S significantly enhanced the expression of SOD and CAT activities. • MDA and O 2 – levels were alleviated in P. chrysosporium cells pretreated with H 2 S. • Inhibition in oxidative stress was ascribed to upregulation in antioxidant enzymes. [ABSTRACT FROM AUTHOR]

Abstract Antioxidative response of Phanerochaete chrysosporium induced by silver nanoparticles (AgNPs) and their toxicity mechanisms were comprehensively investigated in a complex system with 2,4-dichlorophenol (2,4-DCP) and Ag+. Malondialdehyde content was elevated by 2,4-DCP, AgNPs, and/or Ag+ in concentration- and time-dependent manners within 24 h, indicating an increase in lipid peroxidation. However, beyond 48 h of exposure, lipid peroxidation was alleviated by upregulation of intracellular protein production and enhancement in the activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). Comparatively, POD played more major roles in cell protection against oxidative damage. Furthermore, the dynamic change in reactive oxygen species (ROS) level was parallel to that of oxidized glutathione (GSSG), and ROS levels correlated well with GSSG contents (R 2 = 0.953) after exposure to AgNPs for 24 h. This finding suggested that elimination of oxidative stress resulted in depletion of reduced glutathione. Coupled with the analyses of anoxidative responses of P. chrysosporium under the single and combined treatments of AgNPs and Ag+, HAADF-STEM, SEM, and EDX demonstrated that AgNP-induced cytotoxicity could originate from the original AgNPs, rather than dissolved Ag+ or the biosynthesized AgNPs. Graphical abstract Image 1 Highlights • Lipid peroxidation was alleviated via enhancement of SOD, CAT, and POD activities. • POD played a predominant role in effective protection against chronic cell damage. • Suppression of ROS production was closely related to the depletion of GSH at 24 h. • HAADF-STEM and EDX analyses revealed particle-specific toxicity mechanism of AgNPs. [ABSTRACT FROM AUTHOR]

Potential transformations of silver nanoparticles (AgNPs) upon interaction with naturally ubiquitous organic ligands in aquatic environments influence their transport, persistence, bioavailability, and subsequent toxicity to organisms. In this study, differential behaviors of AgNPs and silver ions (Ag + ) towards cysteine (Cys), an amino acid representative of thiol ligands that easily coordinate to Ag + and graft to nanoparticle surfaces, were investigated in the aspects of bioremediation and their toxicity to Phanerochaete chrysosporium . Total Ag removal, 2,4-dichlorophenol (2,4-DCP) degradation, extracellular protein secretion, and cellular viability were enhanced to some extent after supplement of various concentrations of cysteine under stress of AgNPs and Ag + . However, an obvious decrease in total Ag uptake was observed after 5–50 μM cysteine addition in the groups treated with 10 μM AgNPs and 1 μM Ag + , especially at a Cys:Ag molar ratio of 5. More stabilization in uptake pattern at this ratio was detected under Ag + exposure than that under AgNP exposure. Furthermore, in the absence of cysteine, all Ag + treatments stimulated the generation of reactive oxygen species (ROS) more significantly than high-dose AgNPs did. However, cysteine supply under AgNP/Ag + stress aggravated ROS levels, albeit alleviated at 100 μM Ag + , indicating that the toxicity profiles of AgNPs and Ag + to P. chrysosporium could be exacerbated or marginally mitigated by cysteine. The results obtained were possibly associated with the lability and bioavailability of AgNP/Ag + -cysteine complexes. [ABSTRACT FROM AUTHOR]

This study investigated the influence of silver ions (Ag + ) on the cytotoxicity of silver nanoparticles (AgNPs) in Phanerochaete chrysosporium and noted the degree of extracellular secretions in response to the toxicant's stress. Oxalate production was elicited with moderate concentrations of 2,4-dichlorophenol (2,4-DCP) and AgNPs reaching a plateau at 10 mg/L and 10 μM, respectively. Increased oxalate accumulation was accompanied by higher activities of manganese peroxidase (MnP) and lignin peroxidase (LiP). However, the secretion of oxalate, MnP and LiP was significantly inhibited owing to Ag + incorporation into AgNP solution. Production of extracellular polymeric substances (EPS) significantly elevated with an increase in 2,4-DCP concentrations; however, after 24 h of exposure to 100 mg/L 2,4-DCP, an obvious decrease in EPS occurred, indicating that part of EPS could be consumed as carbon and energy sources to ameliorate biological tolerance to toxic stress. Furthermore, AgNP-induced “particle-specific” cytotoxicity was substantially enhanced with additional Ag + as evidenced by its significant negative impact on cellular growth, plasma membrane integrity, and morphological preservation compared with AgNPs at equal Ag concentration. [ABSTRACT FROM AUTHOR]

The growing potential of quantum dots (QDs) in biomedical applications has raised considerable concerns regarding their toxicological impact. Consequently, there has been a need to understand the underlying toxicity mechanism of QDs. In this work, we comprehensively investigated the bioaccumulation and toxicity of three CdSe/ZnS QDs (COOH CdSe/ZnS 525, NH 2 CdSe/ZnS 525, and NH 2 CdSe/ZnS 625) in Phanerochaete chrysosporium ( P. chrysosporium ) using confocal laser scanning microscopy, reactive oxygen species (ROS) measurements, and cell viability assays. Confocal laser scanning microscopy analytical results indicated that all the CdSe/ZnS QDs, with the concentration ranging from 10 to 80 nM, could accumulate largely in the hyphae and induce the generation of ROS, showing a direct toxicity to P. chrysosporium . And the bioaccumulation and toxicity of CdSe/ZnS QDs presented dose-dependent and time-dependent effects on P. chrysosporium . Furthermore, the CdSe/ZnS QDs-induced cytotoxicity was also related to their physicochemical properties, including particle size and surface charges: NH 2 CdSe/ZnS 525 with small size was more cytotoxic as compared to NH 2 CdSe/ZnS 625 with large size, and the smaller negative charged NH 2 CdSe/ZnS 525 resulted in greater cytotoxicity than the larger negative charged COOH CdSe/ZnS 525. The obtained results provide valuable information for exploring and understanding of toxicity mechanism of QDs in living cells. [ABSTRACT FROM AUTHOR]

This study investigated the performance of immobilized Phanerochaete chrysosporium loaded with nitrogen-doped TiO 2 nanoparticles in the treatment of raw landfill leachate with a very low biodegradability ratio (BOD 5 /COD) of 0.09. The effects of various operating parameters, such as initial chemical oxygen demand (COD) concentration, pH, temperature, and biosorbent dosage, were evaluated with respect to the removal efficiency of total organic carbon (TOC) and ammonia nitrogen (NH 3 –N). For the immobilized biosorbents, an optimum pH of 6.0 for TOC and 7.0 for NH 3 –N were found suitable for TOC and NH 3 –N removal at temperature of 37 °C, respectively. The most superior removal efficiencies of TOC and NH 3 –N of landfill leachate were over 75% and 74% in 72 h at an initial COD concentration of 200 mg L −1 , respectively. In addition, heavy metals were partly removed by the immobilized biosorbents during the process of landfill leachate treatment. The species and mass percentage of organic compounds in landfill leachate after the treatment were found to have considerably declined according to the gas chromatography coupled with mass spectrometry (GC–MS) system. These results indicate that the immobilized P. chrysosporium loaded with nitrogen-doped TiO 2 nanoparticles could be a convenient and efficient method for the treatment of landfill leachate. [ABSTRACT FROM AUTHOR]

Immobilized Phanerochaete chrysosporium loaded with TiO 2 nanoparticles (PTNs) are novel high-value bioremediation materials for adsorbing cadmium and for degrading 2,4-dichlorophenol (2,4-DCP). The real-time changes in H + and O 2 fluxes were measured using the noninvasive microtest technique (NMT). The H + influx increased after the addition of 2,4-DCP, and shifted to efflux following the addition of Cd 2+ . The O 2 flux decreased after the addition of both 2,4-DCP and Cd 2+ . A larger Cd 2+ flux was immediately observed after exposure to 0.5 mM Cd 2+ (−351.25 pmol cm −2 s −1 ) than to 0.1 mM Cd 2+ (−107.47 pmol cm −2 s −1 ). The removal of Cd 2+ by the PTNs increased more after treatment with the 0.5 mM exposure solution (27.6 mg g −1 ) than with the 0.1 mM exposure solution (3.49 mg g −1 ). The enzyme activities were analyzed to review the antioxidative defense system of PTNs in a solution containing various concentrations of Cd 2+ . The activities of the coenzyme nicotinamide adenine dinucleotide (NADH) oxidase as well as the enzyme catalase (CAT) plateaued at 6.5 U g −1 FW and 9.7 U g −1 FW, respectively, after exposure to 0.25 mM Cd 2+ . The activity of superoxide dismutase (SOD) increased gradually in solutions containing 0.1–0.6 mM Cd 2+ , and eventually reached a maximum (68.86 U g −1 FW). These results illustrate how the antioxidative defense system and the physiological fluxes of PTNs respond to the stress caused by toxic pollutants. [ABSTRACT FROM AUTHOR]

A novel biosorbent, polyvinyl alcohol (PVA)-immobilized Phanerochaete chrysosporium , was applied to the bioremediation of composite-polluted wastewater, containing both cadmium and 2,4-dichlorophenol (2,4-DCP). The optimum removal efficiency achieved was 78% for Cd(II) and 95.4% for 2,4-DCP at initial concentrations of 20 mg/L Cd(II) and 40 mg/L 2,4-DCP. PPBs had significantly enhanced the resistance of P. chrysosporium to 2,4-DCP, leading to the degradation rates of 2,4-DCP beyond 90% with varying initial 2,4-DCP concentrations. This research demonstrated that 2,4-DCP and secreted proteins might be used as carbon and nitrogen sources by PVA-immobilized P. chrysosporium beads (PPBs) for Cd(II) removal. Fourier transform infrared spectroscopy analysis showed that hydroxyl and carboxyl groups on the surface of PPBs were dominant in Cd(II) binding. The mechanism underlying the degradation of 2,4-DCP into fumaric acid and 1-hexanol was investigated. The adsorption–desorption studies indicated that PPBs kept up to 98.9% of desorption efficiency over three cycles. [ABSTRACT FROM AUTHOR]

Despite the knowledge about increasing discharge of silver nanoparticles (AgNPs) into wastewater and its potential toxicity to microorganisms, the interaction of AgNPs with heavy metals in the biological removal process remains poorly understood. This study focused on the effect of AgNPs (hydrodynamic diameter about 24.3 ± 0.37 nm) on the removal of cadmium (Cd(II)) by using a model white rot fungus species, Phanerochaete chrysosporium . Results showed that the biological removal capacity of Cd(II) increased with the concentration of AgNPs increasing from 0.1 mg/L to 1 mg/L. The maximum removal capacity (4.67 mg/g) was located at 1 mg/L AgNPs, and then decreased with further increasing AgNPs concentration, suggesting that an appropriate concentration of AgNPs has a stimulating effect on the removal of Cd(II) by P. chrysosporium instead of an inhibitory effect. Results of Ag + and total Ag concentrations in the solutions together with those of SEM and XRD demonstrated that added AgNPs had undergone oxidative dissolution and transported from the solution to the surface of fungal mycelia (up to 94%). FTIR spectra confirmed that amino, carboxyl, hydroxyl, and other reducing functional groups were involved in Cd(II) removal, AgNPs transportation, and the reduction of Ag + to AgNPs. [ABSTRACT FROM AUTHOR]

Abstract: This study details a novel method for the extracellular microbial synthesis of cadmium sulfide (CdS) quantum dots (QDs) by the white rot fungus Phanerochaete chrysosporium. P. chrysosporium was incubated in a solution containing cadmium nitrate tetrahydrate, which became yellow from 12h onwards, indicating the formation of CdS nanocrystals. The purified solution showed a maximum absorbance peak between 296 and 298nm due to CdS particles in the quantum size regime. The fluorescence emission at 458nm showed the blue fluorescence of the nanoparticles. X-ray analysis of the nanoparticles confirmed the production of CdS with a face-centered cubic (fcc) crystal structure. The average grain size of the nanoparticles was approximately 2.56nm, as determined from the full width at half-maximum (FWHM) measurement of the most intense peak using Scherer's equation. Transmission electron microscopic analysis showed the nanoparticles to be of a uniform size with good crystallinity. The changes to the functional groups on the biomass surface were investigated through Fourier transform infrared spectroscopy. Furthermore, the secretion of cysteine and proteins was found to play an important role in the formation and stabilization of CdS QDs. In conclusion, our study outlines a chemical process for the molecular synthesis of CdS nanoparticles. [Copyright &y& Elsevier]

• Influences caused by mixed electrolytes were mainly dominated by divalent cations. • Addition of Ca2+, Mg2+, and HA facilitated AgNP stimulation for microbial activity. • AgNP stimulation arose from its reduced direct contact and interaction with cells. • In monovalent electrolytes, the dominating mode of action of AgNPs was Ag+ release. In this study, influences of cations (Na+, K+, Ca2+, and Mg2+), anions (NO 3 −, Cl−, and SO 4 2−), and humic acid (HA) on the antimicrobial efficacy of silver nanoparticles (AgNPs)/Ag+ against Phanerochaete chrysosporium were investigated by observing cell viability and total Ag uptake. K+ enhanced the antimicrobial toxicity of AgNPs on P. chrysosporium , while divalent cations decreased the toxicity considerably, with preference of Ca2+ over Mg2+. Impact caused by a combination of monovalent and divalent electrolytes was mainly controlled by divalent cations. Compared to AgNPs, however, Ag+ with the same total Ag content exhibited stronger antimicrobial efficacy towards P. chrysosporium , regardless of the type of electrolytes. Furthermore, HA addition induced greater microbial activity under AgNP stress, possibly originating from stronger affinity of AgNPs over Ag+ to organic matters. The obtained results suggested that antimicrobial efficacy of AgNPs was closely related to water chemistry: addition of divalent electrolytes and HA reduced the opportunities directly for AgNP contact and interaction with cells through formation of aggregates, complexes, and surface coatings, leading to significant toxicity reduction; however, in monovalent electrolytes, the dominating mode of action of AgNPs could be toxic effects of the released Ag+ on microorganisms due to nanoparticle dissolution. [ABSTRACT FROM AUTHOR]