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Concurrent methylation and demethylation of arsenic by fungi and their differential expression in the protoplasm proteome
2017
Su, Shiming | Zeng, Xibai | Bai, Lingyu | Wang, Yanan | Zhang, Lili | Li, Mansheng | Wu, Cuixia
Microbial methylation and demethylation are central to arsenic's (As) biogeochemical cycling. Here, the transformations of monomethylarsonic acid (MMA(V)) (50 mg L−1) for 15 days in cells of As-methylating fungi, Fusarium oxysporum CZ-8F1, Penicillium janthinellum SM-12F4, and Trichoderma asperellum SM-12F1, were evaluated, and trace concentrations of As(III) and As(V) were observed in fungal cell extracts. Trace amounts of DMA(V) were also detected in MMA(V) and P. janthinellum SM-12F4 incubations. In situ X-ray absorption near edge structure (XANES) indicated that after exposure to MMA(V) (500 mg L−1) for 15 days, 28.6–48.6% of accumulated As in fungal cells was DMA(V), followed by 18.4–30.3% from As(V), 0–28.1% from As(III), and 4.8–28.9% from MMA(V). The concurrent methylation and demethylation of As occurs in fungal cells. Furthermore, a majority of proteins involved in metabolism, transport, ATP activity, biosynthesis, signal transduction, DNA activity, translation, and oxidative stress were upregulated in T. asperellum SM-12F1 cells after MMA(V) exposure compared to As(III), As(V), and DMA(V). The detoxification process of T. asperellum SM-12F1 was As species-specific. Methylenetetrahydrofolate reductase (R7YMH0) donation of a methyl group for S-adenosylmethionine (SAM) generation significantly increased following MMA(V) exposure.
Afficher plus [+] Moins [-]Low density polyethylene degradation by filamentous fungi
2021
Polyethylene (PE) is the most abundant non-degradable plastic waste, posing a constant and serious threat to the whole ecosystem. In the present study, the fungal community of plastic wastes contaminating a landfill soil has been studied. After 6 months of enrichment, 95 fungi were isolated, mostly belonging to the Ascomycota phylum. They were screened under in vitro condition: most of fungi (97%) were capable of growing in the presence of PE powder (5–10 g L⁻¹) as sole carbon source. Fusarium strains better tolerated high concentration of PE. Up to 13 strains were chosen for further degradation trails, where the process was monitored by respirometry tests and by observing changes in PE chemical and physical structure by FTIR analysis and SEM images. Major results were observed for Fusarium oxysporum, Fusarium falciforme and Purpureocillum lilacinum, as they caused strong oxidation phenomena and changes in the PE film morphology. Results suggested that the initial oxidation mechanisms targeted first the methyl terminal groups. Changes in the infrared spectra were strongly strain-dependent, denoting the activation of different degradation pathways. Through the SEM analysis, the actual damages provoked by fungi were observed, including swellings, pits and furrows, bumps and partial exfoliations. Considering the rising concern about plastic disposal worldwide, the ability of these fungi to colonize PE and utilize it as carbon source is of great interest, as no pretreatments and pro-oxidant stimulants were needed.
Afficher plus [+] Moins [-]Effectiveness of Dyes Removal by Mixed Fungal Cultures and Toxicity of Their Metabolites
2013
Przystaś, Wioletta | Zabłocka-Godlewska, Ewa | Grabińska-Sota, Elżbieta
Decolorization of brilliant green (0.06 g/L), Evans blue (0.15 g/L), and their mixture (total concentration 0.08 g/L, proportion 1:1 w/w) by fungi was studied. Fungal strains [Pleurotus ostreatus (BWPH), Gloeophyllum odoratum (DCa), and Fusarium oxysporum (G1)] were used separately and as a mixture of them. Zootoxicity (Daphnia magna) and phytotoxicity (Lemna minor) changes were estimated after the end of experiment. Mixtures of fungal strains were less effective in decolorization process than the same strains used separately (as a single strains). After 96 h of experiment, living biomass of strain BWPH removed up to 95.5 %; DCa, up to 84.6 %; G1, up to 79.2 % where mixtures BWPH + DCa removed up to 74.3 %; and BWPH + G1, only up to 32.2 % of used dyes. High effectiveness of dyes removal not always corresponded with decrease of toxicity. The highest decrease of zootoxicity and phytotoxicity (from V to III toxicity class or to even nontoxic) was noticed for single strains, while no changes or slight toxicity decrease was noticed in samples with strains mixtures.
Afficher plus [+] Moins [-]Sublethal Effects of Biogenic Silver Nanoparticles and Silver Nitrate in the Neotropical Fish Prochilodus lineatus: Is the Nanoform Really Less Toxic?
2022
Ferroni, Hellen Ingrid | Bezerra, Vanessa | Risso, Wagner Ezequiel | Martinez, Claudia Bueno dos Reis | Simonato, Juliana Delatim
Biogenic silver nanoparticles (bNAg) have been suggested as a less toxic alternative to ionic silver (Ag), and also a more ecological alternative to synthetic silver nanoparticles (sNAg). However, the differences between the sublethal effects caused by bNAg and silver nitrate (AgNO₃) are hardly known, especially in native fishes of the Neotropical region. Most researchers have only compared the effects of sNAg and AgNO₃. Thus, the objective of this work was to evaluate the effects of bNAg, produced by the fungus Fusarium oxysporum, and to compare these with the effects of AgNO₃ in the Neotropical fish Prochilodus lineatus. The animals were exposed for 24 and 96 h at nominal concentrations of 10 and 25 µg L⁻¹ of Ag. At the end of the exposures, Ag accumulation, metallothionein concentration, hematological parameters, plasma glucose and ion concentrations, activity of the main ATPases and carbonic anhydrase in the gills, enzymatic and non-enzymatic antioxidants, lipid peroxidation, and neurotoxic effects were evaluated. Both bNAg and AgNO₃ caused Ag accumulation in the blood, gills, and brain, in addition to neurotoxic effects on muscle, alterations in reduced glutathione concentration in the gills, and increased glutathione-S-transferase activity in the liver. Hyperglycemia, ionic imbalances, and alterations in the activity of ion transport enzymes in the gills were also observed. As the effects of bNAg were similar to the effects of AgNO₃, it is concluded that animals exposed to the highest concentration of silver were the most affected, regardless of the form of silver used in the exposure medium.
Afficher plus [+] Moins [-]The potential impact of Octopus cyanea extracts to improve eggplant resistance against Fusarium-wilt disease: in vivo and in vitro studies
2021
The novelty of the present research is conducting a new method in the systemic resistance of plant diseases by using distinct marine extracts. The ability of two octopus extracts to reduce the wilt disease caused by Fusarium oxysporum was observed. The applied methods are soaked roots (SR) and foliar shoots (FS). The antioxidant enzyme activities, percent disease index (PDI), and growth parameters were measured. In vitro antifungal potential of the octopus extracts against F. oxysporum was examined. The obtained result shows that SR extracts reduced PDI. Additionally, all the tested treatments promoted the growth and photosynthetic pigments of the infected plants. SR (in ethanolic extracts) was the most prominent inducer which offered a high advancement in the total soluble protein contents. Also, SR (in methanolic extracts) was the most suitable inducer which provided a very necessary development not only in the total phenol but also in the peroxidase (POD) and polyphenol oxidase (PPO) activities. GC-MS investigation of the octopus extracts exhibited that the compounds which possess antifungal activity were furoscrobiculin B and/or eugenol. They demonstrated a notable antifungal potential against F. oxysporum with a maximum activity of 38.5 and 12.7 mm ZOI after the treatment with the ethanolic and methanolic extract, respectively. FTIR results illustrated the functional group of the compound responsible for the antifungal activity. Additionally, an atomic absorption result reveals that there are traces of metals detected such as Pb, Ag, Cu, Zn, and Mg. The antifungal activity was decreased as the concentrations were reduced. Accordingly, the present extracts may be used as the vital agents in the agricultural field to restrain the plant pathogenic fungi, especially F. oxysporum from a proliferation.
Afficher plus [+] Moins [-]Impact of rhizosphere microorganisms on arsenic (As) transformation and accumulation in a traditional Chinese medical plant
2021
Li, Jiao-Jiao | Yang, Long | Miao, Cui-Ping | Teng, Ya-Jun | Fu, Zi-Hao | Cheng, Chang-Lei | Chang, Xue-Xiu | Qian, Yu | Zhao, Li-Xing
Panax notoginseng is an important traditional medicinal plant, but the commercial value is threatened by root-rot disease caused by rhizosphere microbes and a potential health risk caused by plant arsenic (As) accumulation. Whether rhizospheric microbes isolated from P. notoginseng rhizosphere soil could impact As uptake and transport into P. notoginseng is not yet known. Among the three root-rot disease-causing pathogens Fusarium flocciferum (PG 1), Fusarium oxysporum (PG 2), and Fusarium solani (PG 3) and one root-rot disease biocontrol fungus Trichoderma koningiopsis (FC 1) and five biocontrol-exerting bacterial species Bacillus siamensis (BC 1), Delftia acidovorans (BC 2), Brevibacillus formosus (BC 3), Mortierella alpine (BC 4), and Bacillus subtilis (BC 5), one As-resistant pathogen and four biocontrol microorganisms with As-resistant ability were identified. The As-transforming ability of the identified fungi and bacteria was ranked in the order of FC 1 > PG 1 and BC 2 > BC 3 > BC 1, respectively. Then, the As-resistant biocontrol and pathogenic microbes were initiated to colonize the rhizosphere of 1-year-old P. notoginseng seedlings growing in artificially As(V)-contaminated soil to evaluate the impact of microbe inoculation on P. notoginseng As uptake and transport capacity. Concentration of As in P. notoginseng tissues decreased in the order of the sequence stem > root > leaf. Compared to treatment without colonization by microorganism, inoculation with microorganisms increased As root uptake efficiency and root As concentration, especially under treatment of inoculation by BC 2 and PG 1 + BC 2. As transport efficiency from root to stem decreased by inoculation with microorganism, especially under treatment with inoculation of BC 2 and PG 1 + BC 2. However, the impact of microorganism colonization on As stem to leaf transport efficiency was not obvious. In summary, inoculation with rhizosphere microbes may increase As accumulation in P. notoginseng root, especially when using bacteria with high As transformation ability. Therefore, it is necessary to evaluate the As transformation capacity before applying biological control microorganism to the rhizosphere of P. notoginseng.
Afficher plus [+] Moins [-]Comparison of Iodide and Iodate Accumulation and Volatilization by Filamentous Fungi during Static Cultivation
2017
Five common fungal strains, Cladosporium cladosporioides, Aspergillus clavatus, Penicillium citrinum, Fusarium oxysporum, and Alternaria alternata, were cultivated in presence of iodide and iodate to evaluate their efficiency in iodine biovolatilization and bioaccumulation. Our results suggest that iodide and iodate bioaccumulation by microscopic filamentous fungi is similar although the biological transformation into volatile iodine compounds is driven by various pathways resulting in higher volatilization efficiency of iodate. Thus, the mobilization of iodate by filamentous fungi is superior to iodide mobilization. Our paper is also the first to compare the iodide and iodate volatilization efficiency by microorganisms. Our results highlight the significant role of filamentous fungi in biogeochemistry of iodine, especially in formation of environmentally reactive volatile forms that may contribute to ozone layer destruction.
Afficher plus [+] Moins [-]Effects of soil improvement technology on soil quality in solar greenhouse
2018
Xiao, Wan-li | Wang, Zhe-xin | Wu, Feng-zhi | Zhou, Xin-gang
Currently, cucumber cultivation is mainly through monoculture, as continuous culture leads to the decrease of crop yield and soil quality. In order to improve soil quality to achieve continuous monocultures, soil physicochemical properties, microbial biomass, content of phenolic compounds, and the size of bacterial, fungal, ammonia-oxidizing bacteria (AOB), and Fusarium oxysporum were first evaluated in cucumber monoculture solar greenhouse. Soil improvement technology, including catch wheat (CW), calcium cyanamide disinfection (LN), and straw reactor technology (SR) during summer fallow period, was compared with conventional fallow (CK). Results showed that CW, LN, and SR all significantly increased soil pH, and LN and SR increased soil electrical conductivity (EC); however, CW decreased soil EC. Meanwhile, LN increased soil available N content significantly and SR increased available P content significantly. CW had negative effect on the accumulation of soil available nutrients, conversely, CW and SR had positive effect on the accumulation of microbial biomass carbon (MBC). All the treatments increased the total phenol content in the soil compared with CK. While CW increased the size of bacteria, AOB in the soil inhibited fungal and wilt pathogen size. LN also increased the size of soil bacteria and reduced the size of fungi. The comprehensive evaluation of all treatments showed that CW could control soil nutrient loss and improve the continuous cropping soil, making the soil transform from fungi to bacteria type. All the treatments accelerate the accumulation of phenolic compound, while whether or not developing autotoxicity requires further investigation.
Afficher plus [+] Moins [-]Azole antifungal resistance in fungal isolates from wastewater treatment plant effluents
2021
Assress, Hailemariam Abrha | Selvarajan, Ramganesh | Nyoni, Hlengilizwe | Ogola, Henry Joseph Oduor | Mamba, Bhekie B. | Msagati, Titus A. M.
Wastewater treatment plants (WWTPs) can be significant sources of antifungal resistant fungi, which can disseminate further in the environment by getting into rivers together with effluents discharged from WWTPs and pose a risk for human health. In this study, the presence of azole resistance was determined in fungal isolates from treated effluents of two WWTPs using the standard microdilution method from Clinical and Laboratory Standards Institute (CLSI). A total of 41 fungal isolates representing 23 fungal species and 16 fungal genera were obtained. Fungal genera related to the known human and/or plant pathogens such as Aspergillus, Fusarium, and Candida were detected. Among the observed species, the susceptibility of Aspergillus fumigatus and Fusarium oxysporum was tested against fluconazole (FCZ), ketoconazole (KTZ), itraconazole (ITZ), and voriconazole (VCZ). The isolate A. fumigatus was susceptible to KTZ, ITZ, and VCZ, while it showed resistance against FCZ. On the contrast, the isolate F. oxysporum showed resistance to KTZ, ITZ, and VCZ. Comparatively, VCZ showed highest activity against both A. fumigatus and F. oxysporum. Analysis of the gene Cyp51A for the A. fumigatus isolate showed no evidence of drug resistance that could be related to point mutations and/or tandem repeats in the gene. To the best of our knowledge, this is the first susceptibility test study on A. fumigatus and F. oxysporum isolates from the WWTPs of South Africa. In conclusion, this study indicated an urgent need for thorough investigation with larger group of fungal isolates from different regions of South Africa to broadly understand the role of WWTPs in the dissemination of azole antifungal drug resistance.
Afficher plus [+] Moins [-]Novel preparation of fungal conidiophores biomass as adsorbent for removal of phosphorus from aqueous solution
2020
Kalaimurugan, Dharman | Durairaj, Kaliannan | Kumar, Alagarasan Jagadeesh | Senthilkumar, Palaninaicker | Venkatesan, Srinivasan
The present study focused on phosphorus adsorption by novel fungal conidiophores biomass in aqueous solution. Fungal Conidiophores biomass was prepared from the fungal strains Aspergillus oryzae (YFK) and Fusarium oxysporum (YVS2). The functional groups and morphology of Conidiophores Biomass (CB) from these strains were characterized by FTIR and SEM. FTIR confirms the presence of alcohol, carboxylic acid, carbon dioxide, cyclic alkene, amine, alkene, fluoro compound, and halo compound groups. Batch mode study was carried out with two CB’s such as Aspergillus oryzae CB (ACB) and Fusarium oxysporum CB (FCB) with initial concentration of phosphorus ranging from 20 to 100 mg L⁻¹. Based on the batch experiments, the adsorption kinetics (pseudo first order and pseudo second order), isotherms (Freundlich and Langmuir models), and thermodynamic (standard entropy, energy, and enthalpy) parameters were calculated. The adsorption kinetics and isotherm studies showed that the adsorption data well fitted with PSO kinetic model. From the isotherm results, it was found that ACB and FCB exhibited highest adsorption capacity 25.64 mg g⁻¹ and 26.32 mg g⁻¹ of phosphorus respectively at the optimal condition of pH (7), time (90 min), dose (250 mg), and room temperature (35 °C). Thermodynamics values were found to be endothermic and spontaneous in nature for phosphorus adsorption. Finally, the results suggested that the ACB and FCB are economically feasible cost-effective adsorbent for removal of phosphorus in wastewater treatment. Graphical abstract
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