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Competition shapes evolution. Toxic metals and metalloids have exerted selective pressure on life since the rise of the first organisms on the Earth, which has led to the evolution and acquisition of resistance mechanisms against them, as well as mechanisms to weaponize them. Microorganisms exploit antimicrobial metals and metalloids to gain competitive advantage over other members of microbial communities. This exerts a strong selective pressure that drives evolution of resistance. This review describes, with a focus on arsenic and copper, how microorganisms exploit metals and metalloids for predation and how metal- and metalloid-dependent predation may have been a driving force for evolution of microbial resistance against metals and metalloids.
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Metaloides , Cobre/toxicidadeRESUMO
The Gram-positive bacterium Paenibacillus taichungensis NC1 was isolated from the Zijin gold-copper mine and shown to display high resistance to arsenic (MICs of 10 mM for arsenite in minimal medium). Genome sequencing indicated the presence of a number of potential arsenic resistance determinants in NC1. Global transcriptomic analysis under arsenic stress showed that NC1 not only directly upregulated genes in an arsenic resistance operon but also responded to arsenic toxicity by increasing the expression of genes encoding antioxidant functions, such as cat, perR, and gpx. In addition, two highly expressed genes, marR and arsV, encoding a putative flavin-dependent monooxygenase and located adjacent to the ars resistance operon, were highly induced by As(III) exposure and conferred resistance to arsenic and antimony compounds. Interestingly, the zinc scarcity response was induced under exposure to high concentrations of arsenite, and genes responsible for iron uptake were downregulated, possibly to cope with oxidative stress associated with As toxicity. IMPORTANCE Microbes have the ability to adapt and respond to a variety of conditions. To better understand these processes, we isolated the arsenic-resistant Gram-positive bacterium Paenibacillus taichungensis NC1 from a gold-copper mine. The transcriptome responding to arsenite exposure showed induction of not only genes encoding arsenic resistance determinants but also genes involved in the zinc scarcity response. In addition, many genes encoding functions involved in iron uptake were downregulated. These results help to understand how bacteria integrate specific responses to arsenite exposure with broader physiological responses.
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Arsênio , Arsenitos , Arsênio/metabolismo , Arsênio/toxicidade , Arsenitos/metabolismo , Arsenitos/toxicidade , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Cobre , Ouro , Ferro , Óperon , Paenibacillus , ZincoRESUMO
The biorecovery of gold (Au) by microbial reduction has received increasing attention, however, the biomolecules involved and the mechanisms by which they operate to produce Au nanoparticles have been not resolved. Here we report that Burkholderia contaminans ZCC is capable of reduction of Au(III) to Au nanoparticles on the cell surface. Exposure of B. contaminans ZCC to Au(III) led to significant changes in the functional group of cell proteins, with approximately 11.1% of the (C-C/C-H) bonds being converted to CO (8.1%) and C-OH (3.0%) bonds and 29.4% of the CO bonds being converted to (C-OH/C-O-C/P-O-C) bonds, respectively. In response to Au(III), B. contaminans ZCC also displayed the ability of extracellular electron transfer (EET) via membrane proteins and could produce reduced riboflavin as verified by electrochemical and liquid chromatography-mass spectrometric results, but did not do so without Au(III) being present. Addition of exogenous reduced riboflavin to the medium suggested that B. contaminans ZCC could utilize indirect EET via riboflavin to enhance the rate of reduction of Au(III). Transcriptional analysis of the riboflavin genes (ribBDEFH) supported the view of the importance of riboflavin in the reduction of Au(III) and its importance in the biorecovery of gold.
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Ouro , Nanopartículas Metálicas , Burkholderia , Elétrons , RiboflavinaRESUMO
Bioremediation of Cd contaminated environments can be assisted by plant-growth-promoting bacteria (PGPB) enabling plant growth in these sites. Here a gram-negative Burkholderia contaminans ZCC was isolated from mining soil at a copper-gold mine. When exposed to Cd(II), ZCC displayed high Cd resistance and the minimal inhibitory concentration was 7 mM in LB medium. Complete genome analysis uncovered B. contaminans ZCC contained 3 chromosomes and 2 plasmids. One of these plasmids was shown to contain a multitude of heavy metal resistance determinants including genes encoding a putative Cd-translocating PIB-type ATPase and an RND-type related to the Czc-system. These additional heavy metal resistance determinants are likely responsible for the increased resistance to Cd(II) and other heavy metals in comparison to other strains of B. contaminans. B. contaminans ZCC also displayed PGPB traits such as 1-aminocyclopropane-1-carboxylate deaminase activity, siderophore production, organic and inorganic phosphate solubilization and indole acetic acid production. Moreover, the properties and Cd(II) binding characteristics of extracellular polymeric substances was investigated. ZCC was able to induce extracellular polymeric substances production in response to Cd and was shown to be chemically coordinated to Cd(II). It could promote the growth of soybean in the presence of elevated concentrations of Cd(II). This work will help to better understand processes important in bioremediation of Cd-contaminated environment.
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Adaptação Fisiológica/fisiologia , Burkholderia/fisiologia , Cádmio/toxicidade , Poluentes do Solo/toxicidade , Biodegradação Ambiental , Cádmio/metabolismo , Ácidos Indolacéticos , Metais Pesados/análise , Mineração , Desenvolvimento Vegetal , Solo/química , Microbiologia do Solo , Poluentes do Solo/análise , Glycine max/metabolismoRESUMO
Two new homoisoflavans, 4'-hydroxy-7-methoxy-3-benzyl-2H-chromene (1) and 3,4-cis-di-O-3-hydroxy-7-methoxy-3-(4-hydroxybenzyl)-4-ethoxychroman (2), one new coumarin, 7-methoxy-3-(4-hydroxybenzyl)coumarin (4), together with seven known phenolic compounds, bonducellin (3), anemarcoumarin A (5), (+)-syringaresinol (6), curuilignan D (7), scopoletin (8), and p-hydroxybenzaldehyde (9), were isolated from Tara (Caesalpinia spinosa Kuntze). The structures of the new compounds were characterized from their 1D and 2D NMR spectral data. All the compounds were isolated from this plant for the first time.
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Caesalpinia/química , Fenóis/isolamento & purificação , Benzopiranos , Cumarínicos , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Fenóis/química , Folhas de Planta/químicaRESUMO
Metals and metalloids are used as weapons for predatory feeding by unicellular eukaryotes on prokaryotes. This review emphasizes the role of metal(loid) bioavailability over the course of Earth's history, coupled with eukaryogenesis and the evolution of the mitochondrion to trace the emergence and use of the metal(loid) prey-killing phagosome as a feeding strategy. Members of the genera Acanthamoeba and Dictyostelium use metals such as zinc (Zn) and copper (Cu), and possibly metalloids, to kill their bacterial prey after phagocytosis. We provide a potential timeline on when these capacities first evolved and how they correlate with perceived changes in metal(loid) bioavailability through Earth's history. The origin of phagotrophic eukaryotes must have postdated the Great Oxidation Event (GOE) in agreement with redox-dependent modification of metal(loid) bioavailability for phagotrophic poisoning. However, this predatory mechanism is predicted to have evolved much later - closer to the origin of the multicellular metazoans and the evolutionary development of the immune systems.
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Dictyostelium , Metais , Fagocitose , Metais/metabolismo , Dictyostelium/metabolismo , Dictyostelium/fisiologia , Evolução Biológica , Acanthamoeba , Animais , Fagossomos/metabolismo , Zinco/metabolismo , Metaloides/metabolismo , Cobre/metabolismo , Disponibilidade Biológica , Mitocôndrias/metabolismoRESUMO
OBJECTIVE: The aim of this study is to identify molecules from traditional Chinese medicine (TCM) with potential activity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its variants. METHODS: We applied the Apriori algorithm to identify important combinations of herbs in the TCM prescriptions for the treatment of coronavirus disease 2019 (COVID-19). Then, we explored the active components and core targets using network pharmacology. In addition, the molecular docking approach was performed to investigate the interaction of these components with the main structural and non-structural proteins, as well as the mutants. Furthermore, their stability in the binding pockets was further evaluated with the molecular dynamics approach. RESULTS: A combination of Amygdalus Communis Vas., Ephedra Herba and Scutellaria baicalensis Georgi was selected as the important herbal combination, and 11 main components and 20 core targets against COVID-19 were obtained. These components, including luteolin, naringenin, stigmasterol, baicalein, and so on, were the potentially active compounds against COVID-19. The binding affinity of these compounds with the potential targets was as high as the positive controls. Among them, baicalein could interfere with multiple targets simultaneously, and it also interfered with the interaction between spike protein and angiotensin-converting enzyme 2 receptor. Additionally, almost all the systems reached stability during dynamics simulation. CONCLUSION: The combination of A. communis, Ephedra Herba and S. baicalensis was the most important herbal combination for the treatment of COVID-19. Baicalein may be a potential candidate against SARS-CoV-2 and its variants. Please cite this article as: Song JB, Zhao LQ, Wen HP, Li YP. Herbal combinations against COVID-19: A network pharmacology, molecular docking and dynamics study. J Integr Med. 2023;21(6):593-604.
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COVID-19 , Medicamentos de Ervas Chinesas , Humanos , Simulação de Acoplamento Molecular , SARS-CoV-2 , Farmacologia em Rede , Medicamentos de Ervas Chinesas/farmacologia , Medicamentos de Ervas Chinesas/uso terapêutico , Medicina Tradicional ChinesaRESUMO
Mucilaginibacter gossypii P3, which was isolated from the sub-surface soil of the Zijin Gold and Copper Mine, displayed extremely high resistance to multiple heavy metal(loid)s and contained two novel ars operons. Complete genome sequencing of P3 yielded a single, closed genome of 7,187,928 bp, with GC content of 42.79%.
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BACKGROUND: Most of the recent research on nightmare distress and depressive symptoms has focused on adolescents and students, with less research on the nurse population. Emergency department nurses are at high risk for nightmare distress and depressive symptoms, but no studies have been conducted to explore the relationship between the two; thus, further investigation is needed. AIM: To understand the relationship between nightmare distress and depressive symptoms among emergency department nurses in China. METHODS: A convenience sampling method was used to select 280 emergency department nurses from nine provinces, including Jiangxi, Sichuan, Jiangsu, and Shanxi Provinces. The Chinese version of the Nightmare Distress Questionnaire and the Center for Epidemiological Studies Depression Scale (CES-D) were administered. RESULTS: Emergency department nurses' nightmare distress scores were positively associated with depressive symptom scores (r = 0.732), depressed affect (r = 0.727), somatic symptoms (r = 0.737), and interpersonal difficulty (r = 0.647). Further multiple linear regression analyses showed that education level, work pressure, self-reported health, and CES-D scores were factors that influenced nightmare distress among Chinese emergency department nurses (P < 0.05). CONCLUSION: Nightmare distress is closely associated with depressive symptoms in Chinese emergency department nurses, and early intervention is recommended for professionals with this type of sleep disorder to reduce the occurrence of depressive symptoms.
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Strains of the genus Mucilaginibacter, belonging to the phylum Bacteroidetes, have been noted for exhibiting high genome plasticity and for the vigorous production of extracellular polymeric substances (EPS). Here we analyzed the composition and properties of EPS generated by M. rubeus P2, isolated from a gold-copper mine and exhibiting extremely high resistance to multiple heavy metals. Production of EPS increased significantly upon exposure to elevated concentrations of Cu(II) and Zn(II), but not Au(III). In addition, the EPS produced by M. rubeus P2 displayed extremely high bio-adsorption of As(III), Cu(II) and Au(III), but not of Zn(II). Moreover, EPS production in Mucilaginibacter rubeus P2 exposed to 1 mM of Cu(II) was 8.5 times higher than EPS production in the same strain without metal (loid)-exposure. These findings constitute the basis for a future use of these EPS-overproducing bacteria in bioremediation of heavy metal contaminated environments. The functional groups, especially -SH, CO, and N-H/C-N in the fingerprint zone of glutathione (GSH) and polysaccharides-like components of EPS, were the main components of EPS involved in both Zn(II) and Cu(II) binding and removal. Around 31.22% and 5.74% of Cu(II)-treated EPS was shown to exist as (CO) structures and these structures were converted into C-OH and O-C-O upon exposure to Cu(II), respectively. In contrast, (C-OH/C-O-C/P-O-C) groups in EPS were observed to be positively correlated to increasing concentrations of Zn(II) in strain P2. Furthermore, the complete genome of M. rubeus P2 helped us to identify 350 genes involved in carbohydrate metabolism, some of which are predicted to be involved in EPS production and modification. This work describes the first detailed biochemical and biophysical analysis of EPS from any strain of Mucilaginibacter with unique heavy metal binding properties. The results will be useful for a better understanding of how microorganisms such as M. rubeus P2 adapt to heavy metal polluted environments and how this knowledge can potentially be harnessed in biotechnological applications such as industrial waste water purification, bioremediation of heavy metal contaminated soil and beneficial plant microbe interactions. The toolbox provided in this paper will provide a valuable basis for future studies.
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Metais Pesados , Zinco , Adsorção , Bacteroidetes , CobreRESUMO
This work developed a relatively inexpensive and layers-film construction electrochemical sensor for DNA recognition and its performance was investigated. The Fe(3)O(4) magnetic nanoparticles-cysteine were immobilized on the carbon paste electrode (CPE) surface using magnetic force. Multiwalled carbon nanotubes (MWCNTs), gold nanoparticles (GNPs), and chitosan (Chi) were used successively to coat on the electrode surface. The thiolated capture probe was assembled and competitively hybridized with the target nucleic acid and biotinylated response probe. The electrochemical behavior was analyzed by cyclic voltammetry and electrochemical impedance spectroscopy. In addition, the sensor performance was also analyzed by introducing the notion of detection efficiency. The experimental results showed that although the electron transfer capability of the CPE is less strong than that of a metal electrode used in the DNA sensor, the materials modified on the CPE could significantly improve the performance. A detection limit of 1 nM of target DNA and a sensitivity of 2.707 × 10(3) mA M(-1) cm(-2) were obtained. Although the resulting detection limit was not remarkable, further experiments could improve it.
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Técnicas Biossensoriais/métodos , DNA/análise , Técnicas Eletroquímicas , Quitosana/química , Cisteína/química , Espectroscopia Dielétrica , Eletrodos , Óxido Ferroso-Férrico/química , Ouro/química , Magnetismo , Nanopartículas Metálicas/química , Nanotubos de Carbono/química , Hibridização de Ácido NucleicoRESUMO
BACKGROUND: This study investigated the differences in clinicopathologic features and surgical treatment between an Italian and a Chinese cohort of premenopausal women with breast cancer, and highlighted the potential advantages of international medical exchange projects. METHODS: Premenopausal women who underwent surgical treatment between 2012 and 2016 at one Italian and one Chinese institution participating in a medical exchange program were compared. Factors associated with the probability to receive mastectomy were determined via logistic analysis. Changes in surgical management at the Chinese institution in the period 2018-2019, after the exchange program, were also evaluated. RESULTS: A total of 505 patients, 318 from Italy and 187 from China, were evaluated. The Chinese patients had more frequently advanced-stage tumours, large tumour size (30.9 vs. 18.1 mm, p < 0.01), invasive carcinoma (92.5 vs. 83.3%, p < 0.01), positive axillary lymph nodes (54.5 vs. 27.4%, p < 0.01), Her-2 positivity (36.4 vs. 22.0%, p < 0.01), and high proliferative index (55.1 vs. 30.2%, p < 0.01). Positive oestrogen receptor status and rates of triple-negative breast cancer did not differ (77.0 vs. 69.5%, p = 0.09 and 14.2 vs. 16%, p = 0.56, respectively). Mastectomy rates were higher among Chinese women (85 vs. 41%, p < 0.001), whereas use of sentinel node biopsy was more frequent among Italian women (77 vs. 33%, p < 0.001). Chinese women had more than 4-fold higher risk of receiving mastectomy. In the last 2 years, the rates of breast-conserving surgery and sentinel node biopsy at the Chinese institution increased from 15 to 23%, and from 33 to 42%, respectively. CONCLUSIONS: Tumour features and surgical strategies for premenopausal breast cancer may differ signiï¬cantly between Italy and China. Since the international exchange program, patients from the Chinese institution have been offered more frequently less invasive surgery. International exchange programs can help in designing epidemiological studies which may be useful for strategies to improve breast cancer management and control.
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The highly heavy metal resistant strain Cupriavidus metallidurans BS1 was isolated from the Zijin gold-copper mine in China. This was of particular interest since the extensively studied, closely related strain, C. metallidurans CH34 was shown to not be only highly heavy metal resistant but also able to reduce metal complexes and biomineralizing them into metallic nanoparticles including gold nanoparticles. After isolation, C. metallidurans BS1 was characterized and complete genome sequenced using PacBio and compared to CH34. Many heavy metal resistance determinants were identified and shown to have wide-ranging similarities to those of CH34. However, both BS1 and CH34 displayed extensive genome plasticity, probably responsible for significant differences between those strains. BS1 was shown to contain three prophages, not present in CH34, that appear intact and might be responsible for shifting major heavy metal resistance determinants from plasmid to chromid (CHR2) in C. metallidurans BS1. Surprisingly, the single plasmid - pBS1 (364.4 kbp) of BS1 contains only a single heavy metal resistance determinant, the czc determinant representing RND-type efflux system conferring resistance to cobalt, zinc and cadmium, shown here to be highly similar to that determinant located on pMOL30 in C. metallidurans CH34. However, in BS1 another homologous czc determinant was identified on the chromid, most similar to the czc determinant from pMOL30 in CH34. Other heavy metal resistance determinants such as cnr and chr determinants, located on megaplasmid pMOL28 in CH34, were shown to be adjacent to the czc determinant on chromid (CHR2) in BS1. Additionally, other heavy metal resistance determinants such as pbr, cop, sil, and ars were located on the chromid (CHR2) and not on pBS1 in BS1. A diverse range of genomic rearrangements occurred in this strain, isolated from a habitat of constant exposure to high concentrations of copper, gold and other heavy metals. In contrast, the megaplasmid in BS1 contains mostly genes encoding unknown functions, thus might be more of an evolutionary playground where useful genes could be acquired by horizontal gene transfer and possibly reshuffled to help C. metallidurans BS1 withstand the intense pressure of extreme concentrations of heavy metals in its environment.
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Residual dichlorodiphenyltrichloroethane (DDT) in the environment and a continuously increasing atmospheric carbon dioxide (CO2) concentration are two issues that have received a lot of attention. This study was conducted using a pot experiment to investigate the interactive effects of elevated CO2 and DDT on the uptake of DDT, the physiological responses and the resulting health risks in three vegetables. These vegetables included Brassica juncea var. foliosa Bailey (B. Bailey), Brassica campestris L. var. communis Tsen et Lee Suzhou Qing (B. Lee) and Brassica campestris L. ssp. pekinensis (Lour.) Olsson Chun Dawang (B. Olsson). Two levels of CO2 and four DDT treatment levels were set up. Results showed 5â¯mgâ¯kg-1 DDT significantly reduced the shoot biomass of B. Bailey when compared to 0â¯mgâ¯kg-1 DDT treatment under ambient CO2 condition. Elevated CO2 concentration stimulated the growth of B. Bailey and B. Lee, increased the DDT uptake in the shoots of both vegetables and the values of some photosynthesis indices, and triggered the activity of peroxidase and catalase in the shoots when compared to the related ambient CO2 treatment. Elevated CO2 concentration increased the values of hazard indexes for non-carcinogenic and cancer risks of all vegetables when compared to the individual ambient CO2 treatment (each of vegetable has an ambient CO2 treatment), especially for B. Bailey (increase amplitude of 123.81%-127.78% at 5â¯mgâ¯kg-1 DDT). Long-term ingestion with these DDT-polluted vegetables might result in an elevated carcinogenic risk and elevated atmospheric CO2 may enhance the non-carcinogenic and carcinogenic risks.
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Brassica/toxicidade , Dióxido de Carbono , Exposição Ambiental/efeitos adversos , Resíduos de Praguicidas/toxicidade , Folhas de Planta/toxicidade , Verduras/toxicidade , Dióxido de Carbono/efeitos adversos , Dióxido de Carbono/metabolismo , DDT/efeitos adversos , Poluição Ambiental/efeitos adversos , Contaminação de Alimentos , Folhas de Planta/química , Folhas de Planta/metabolismo , Medição de RiscoRESUMO
Arsenic is a metalloid that occurs naturally in aquatic and terrestrial environments. The high toxicity of arsenic derivatives converts this element in a serious problem of public health worldwide. There is a global arsenic geocycle in which microbes play a relevant role. Ancient exposure to arsenic derivatives, both inorganic and organic, has represented a selective pressure for microbes to evolve or acquire diverse arsenic resistance genetic systems. In addition, arsenic compounds appear to have been used as a toxin in chemical warfare for a long time selecting for an extended range of arsenic resistance determinants. Arsenic resistance strategies rely mainly on membrane transport pathways that extrude the toxic compounds from the cell cytoplasm. The ars operons, first discovered in bacterial R-factors almost 50 years ago, are the most common microbial arsenic resistance systems. Numerous ars operons, with a variety of genes and different combinations of them, populate the prokaryotic genomes, including their accessory plasmids, transposons, and genomic islands. Besides these canonical, widespread ars gene clusters, which confer resistance to the inorganic forms of arsenic, additional genes have been discovered recently, which broadens the spectrum of arsenic tolerance by detoxifying organic arsenic derivatives often used as toxins. This review summarizes the presence, distribution, organization, and redundance of arsenic resistance genes in prokaryotes.
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Heavy metals (HMs) are compounds that can be hazardous and impair growth of living organisms. Bacteria have evolved the capability not only to cope with heavy metals but also to detoxify polluted environments. Three heavy metal-resistant strains of Mucilaginibacer rubeus and one of Mucilaginibacter kameinonensis were isolated from the gold/copper Zijin mining site, Longyan, Fujian, China. These strains were shown to exhibit high resistance to heavy metals with minimal inhibitory concentration reaching up to 3.5 mM Cu(II), 21 mM Zn(II), 1.2 mM Cd(II), and 10.0 mM As(III). Genomes of the four strains were sequenced by Illumina. Sequence analyses revealed the presence of a high abundance of heavy metal resistance (HMR) determinants. One of the strain, M. rubeus P2, carried genes encoding 6 putative PIB-1-ATPase, 5 putative PIB-3-ATPase, 4 putative Zn(II)/Cd(II) PIB-4 type ATPase, and 16 putative resistance-nodulation-division (RND)-type metal transporter systems. Moreover, the four genomes contained a high abundance of genes coding for putative metal binding chaperones. Analysis of the close vicinity of these HMR determinants uncovered the presence of clusters of genes potentially associated with mobile genetic elements. These loci included genes coding for tyrosine recombinases (integrases) and subunits of mating pore (type 4 secretion system), respectively allowing integration/excision and conjugative transfer of numerous genomic islands. Further in silico analyses revealed that their genetic organization and gene products resemble the Bacteroides integrative and conjugative element CTnDOT. These results highlight the pivotal role of genomic islands in the acquisition and dissemination of adaptive traits, allowing for rapid adaption of bacteria and colonization of hostile environments.
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Here, we report the features and draft genome sequence of Pseudarthrobacter sp. strain AG30, isolated from the Zijin gold and copper mine in China. The genome size of Pseudarthrobacter sp. AG30 was 4,618,494 bp, with a G+C content of 66.2%. Interesting genes and operons putatively conferring resistance to copper and arsenic were identified.
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Caesalpinnone A (1), an unprecedented hybrid of flavan and chalcone, possessing a 10,11-dioxatricyclic [5.3.3.01,6]tridecane-bridged system, and caesalpinflavans A-C (2-4), three new hybrid flavan-chalcones, were isolated from the twigs and leaves of Caesalpinia enneaphylla. Their structures were elucidated by a combination of spectroscopic analyses and single-crystal X-ray diffraction. Caesalpinnone A showed the highest cytotoxicity against the HL-60, SMMC-7721, A-549, MCF-7, and SW-480 human tumor cell lines with an IC50 in the range of 0.54-0.87 µM.
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A method was proposed to remove Cd from contaminated soils by a semi-solid culture containing Aspergillus fumigatus that have a strong resistance to Cd. The removal efficiencies of Cd in different simulated Cd pollution levels were studied and the changes in Cd adsorption and the enrichment in Aspergillus fumigatus were measured. The results showed that Aspergillus fumigatus could remove some Cd from the soil in the semi-solid culture system. When the concentration of Cd was 10 mg·kg-1, the total removal rate of Cd was up to 31%. Meanwhile, the dry weight of Aspergillus fumigatus and the pH of the system were studied during the culture process. The results showed that the dry weight decreased with the increase in culture time and Cd concentration, the maximum decrease rate of dry weight was 64%. The removal efficiency was the best when the pH was varied from 5.6 to 6.0. The changes in different extraction fractions for Cd showed that the main fractions of Cd removed by Aspergillus fumigatus were the acid-soluble fraction and the reducible fraction and the oxidizable fraction of Cd remained essentially unchanged before and after the culturing. The proposed method would provide valuable information for the remediation of heavy metal-contaminated soil by fungi.
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Aspergillus fumigatus/metabolismo , Cádmio/isolamento & purificação , Recuperação e Remediação Ambiental , Poluentes do Solo/isolamento & purificação , Poluição Ambiental , SoloRESUMO
Polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) was used to study the changes of glycoside hydrolase family 6 (GH6 family) genes during the composting of agricultural waste. In addition, a redundancy analysis (RDA) and Monte Carlo permutation test were applied to determine the relationship between the changes to the GH6 family genes and physico-chemical parameters. According to the relative magnitudes of the influence caused by these different parameters on the changes to GH6 family genes, the eight-ranked physico-chemical parameters were pH > pile temperature > total nitrogen (TN) > total organic matter (TOM) > C/N ratio > moisture content > ambient temperature > water soluble carbon (WSC). The eight physico-chemical parameters, which explained 83.1% of the variation of GH6 family genes, confirmed that these parameters had important effects on the GH6 family genes changes. The pH (P=0.002), pile temperature (P=0.004), and TN (P=0.004) had the most significant impacts on these changes. These three significant factors explained 24.92%, 15.57%, and 15.04% of the variation of GH6 family genes, respectively. There were different dominant species which contain GH6 family genes in different stages of composting. The diversity and abundance of GH6 family genes demonstrated these fluctuation trends. The t-value biplots based on the RDA showed that these three significant factors had either positive or negative correlations with the dynamic changes of GH6 family genes and the microbial species contained within GH6 family genes can be generally be divided into five types. The microbial community changes are reflected by the No. 4 to No. 10 bands and these had a significant positive correlation with pile temperature and a significant negative correlation with pH and TN. The microbial community changes reflected by the No. 20 to No. 23 bands had a significant positive correlation with pH and TN.