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1.
Nutrients ; 16(9)2024 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-38732540

RESUMO

Zinc deficiency affects the physical and intellectual development of school-age children, while studies on the effects on intestinal microbes and metabolites in school-age children have not been reported. School-age children were enrolled to conduct anthropometric measurements and serum zinc and serum inflammatory factors detection, and children were divided into a zinc deficiency group (ZD) and control group (CK) based on the results of serum zinc. Stool samples were collected to conduct metagenome, metabolome, and diversity analysis, and species composition analysis, functional annotation, and correlation analysis were conducted to further explore the function and composition of the gut flora and metabolites of children with zinc deficiency. Beta-diversity analysis revealed a significantly different gut microbial community composition between ZD and CK groups. For instance, the relative abundances of Phocaeicola vulgatus, Alistipes putredinis, Bacteroides uniformis, Phocaeicola sp000434735, and Coprococcus eutactus were more enriched in the ZD group, while probiotic bacteria Bifidobacterium kashiwanohense showed the reverse trend. The functional profile of intestinal flora was also under the influence of zinc deficiency, as reflected by higher levels of various glycoside hydrolases in the ZD group. In addition, saccharin, the pro-inflammatory metabolites, and taurocholic acid, the potential factor inducing intestinal leakage, were higher in the ZD group. In conclusion, zinc deficiency may disturb the gut microbiome community and metabolic function profile of school-age children, potentially affecting human health.


Assuntos
Fezes , Microbioma Gastrointestinal , Zinco , Humanos , Microbioma Gastrointestinal/fisiologia , Zinco/deficiência , Zinco/sangue , Criança , Masculino , Feminino , Fezes/microbiologia , Bactérias/classificação , Bactérias/metabolismo , Mucosa Intestinal/metabolismo , Mucosa Intestinal/microbiologia , Metaboloma , Intestinos/microbiologia
2.
Bull Environ Contam Toxicol ; 111(3): 30, 2023 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-37642728

RESUMO

In aquatic ecosystems, arsenate (As(V)) and lead (Pb(II)) frequently coexist but their joint toxicity on microalgae remains unknown. In this study, Chlamydomonas reinhardtii was exposed to various levels of combined As(V) and Pb(II) treatments. The cell growth, respiration, pigment synthesis, polysaccharides and protein secretion as well as As speciation of C. reinhardtii were analyzed. The low-level coexistence of As(V) and Pb(II) had a stimulatory effect, as indicated by enhanced cell proliferation. In the middle-level coexistence, the cells resisted the toxicity by significant increasing protein secretion. Under high-level coexistence, the presence of Pb(II) inhibited the efflux of As and caused the decline of cell numbers and occurrence of cell lysis, indicating that the interaction mode between As(V) and Pb(II) switched to synergistic. Taken together, the above findings may deepen the understanding of detoxification mechanisms of algae upon exposure to combined metal(loid)s in aqueous environments.


Assuntos
Arseniatos , Chlamydomonas reinhardtii , Arseniatos/toxicidade , Ecossistema , Chumbo/toxicidade
3.
Eur J Clin Pharmacol ; 79(10): 1357-1363, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37540265

RESUMO

PURPOSE: The purpose of this article is to examine the efficacy of oxytocin in treating core symptoms of autism spectrum disorder (ASD) with children. METHODS: A systematic literature search was conducted to identify randomized controlled trials (RCTs) of oxytocin for the treatment of core symptoms in children with ASD. The search included studies published between January 1, 1999 and March 15, 2023, that were randomized, single or double-blinded, and included a placebo control group. Standard screening rules were applied to select relevant studies, resulting in the inclusion of five RCTs involving 486 children with ASD. RESULTS: Ultimately, a total of five RCTs, involving 486 children with ASD, were included in the review using standard screening rules.One of the included studies demonstrated a statistically significant improvement in Social Responsiveness Scale (SRS) and Repetitive Behavior Scale-Revised (RBS) scores when children with ASD were treated with oxytocin (24 IU/2 days for 6 weeks). The improvement in core symptoms persisted at the 6-month follow-up. The meta-analysis findings suggested that oxytocin might have a moderate effect in improving the core symptom of narrow interests and repetitive stereotyped behaviors in children with ASD. CONCLUSION: While the therapeutic value of oxytocin in treating core symptoms of ASD in children is not fully established, the results of this meta-analysis indicate a potential moderate effect. However, further studies with larger sample sizes and more robust RCTs are needed to directly demonstrate the efficacy of oxytocin. Future research should also focus on effect size and outcome evaluation accuracy while minimizing bias in RCT experiments.


Assuntos
Transtorno do Espectro Autista , Ocitocina , Humanos , Criança , Ocitocina/uso terapêutico , Transtorno do Espectro Autista/tratamento farmacológico , Avaliação de Resultados em Cuidados de Saúde , Grupos Controle
4.
Environ Toxicol Chem ; 42(9): 1960-1970, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37283217

RESUMO

Phosphorus (P) is critical for algal growth and resistance to environmental stress. However, little is known about the effects of P supply on the lead (Pb) toxicity and accumulation in microalgae. We set up two P concentrations, 315 (PL ) and 3150 µg L-1 (PH ), in algal culture, and the responses of Chlamydomonas reinhardtii to various Pb treatments (0, 200, 500, 1000, 2000, and 5000 µg L-1 ) were investigated. Compared with the PL condition, PH promoted cell growth but reduced cellular respiration by approximately 50%. Moreover, PH alleviated damage to the photosynthetic system in algal cells after Pb stress. After exposure to 200-2000 µg L-1 Pb, higher Pb2+ concentrations and Pb removal were observed in the PL medium. However, under exposure to 5000 µg L-1 Pb, less Pb2+ was present but more Pb was removed by the algal cells in the PH medium. More P supply enhanced the secretion of extracellular fluorescent substances by C. reinhardtii. Transcriptomic analysis showed that genes associated with synthesis of phospholipids, tyrosine-like proteins, ferredoxin, and RuBisCO were up-regulated after Pb exposure. Together the findings of our study demonstrated the critical roles of P in Pb accumulation and resistance in C. reinhardtii. Environ Toxicol Chem 2023;42:1960-1970. © 2023 SETAC.


Assuntos
Chlamydomonas reinhardtii , Chumbo/toxicidade , Chumbo/metabolismo , Fósforo/farmacologia
5.
Appl Microbiol Biotechnol ; 107(2-3): 943-954, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36625912

RESUMO

Many fungi are able to produce extracellular polymeric substances (EPS) for environmental, food, and industrial applications. This study evaluated the extraction (in vivo) of EPS from Rhodotorula mucilaginosa, a typical yeast with abundant EPS. Three extracting methods were set, i.e., heating, addition of NaCl during heating, and cation exchange resin (CER). The abundance of extracted proteins and polysaccharides showed evident contrasts (elevated to ~ 600 and 1700 mg/L, respectively) after heating at 70 °C in water. Although the higher temperature will increase the extracted abundance of EPS, the leakage of DNA would be enhanced due to cell rupture. The addition of NaCl further promoted the efficiency of extraction, either for proteins (from ~ 550 to ~ 650 mg/L) or polysaccharides (from ~ 1700 to ~ 2010 mg/L). Moreover, the biochemical results showed that the extracted abundance of EPS via heating was dramatically higher than that via CER. Additionally, DNA leakage in the CER treatment (2.0 g/g DW) was significantly higher (up to > 6 mg/L) than that under heating at 70 °C (< 2 mg/L). Furthermore, the three-dimensional excitation-emission matrix spectra showed two characteristic peaks of emission/excitation wavelength at 280/300 and 280/350, suggesting the relative high diversity of organic matters in EPS after heating treatments. Finally, a fluctuation of polysaccharide abundance in EPS at 500-1500 mg/L Pb2+ level was elucidated by the extraction based on heating treatment. This study hence confirmed that the heating method might be recommended for extraction of EPS from fungi in vivo KEY POINTS: • 3D-EEM results indicated that heating could extract more EPS compared with CER. • Heating treatments showed lower DNA leakage from fungi than CER treatments. • Addition of NaCl promoted the detachment of EPS from fungal cells in vivo.


Assuntos
Matriz Extracelular de Substâncias Poliméricas , Cloreto de Sódio , Polissacarídeos , Proteínas , Fungos , Esgotos/química
6.
Front Psychiatry ; 13: 993077, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36213933

RESUMO

Background: Early detection of children with autism spectrum disorder (ASD) and comorbid intellectual disability (ID) can help in individualized intervention. Appropriate assessment and diagnostic tools are lacking in primary care. This study aims to explore the applicability of machine learning (ML) methods in diagnosing ASD comorbid ID compared with traditional regression models. Method: From January 2017 to December 2021, 241 children with ASD, with an average age of 6.41 ± 1.96, diagnosed in the Developmental Behavior Department of the Children's Hospital Affiliated with the Medical College of Zhejiang University were included in the analysis. This study trained the traditional diagnostic models of Logistic regression (LR), Support Vector Machine (SVM), and two ensemble learning algorithms [Random Forest (RF) and XGBoost]. Socio-demographic and behavioral observation data were used to distinguish whether autistic children had combined ID. The hyperparameters adjustment uses grid search and 10-fold validation. The Boruta method is used to select variables. The model's performance was evaluated using discrimination, calibration, and decision curve analysis (DCA). Result: Among 241 autistic children, 98 (40.66%) were ASD comorbid ID. The four diagnostic models can better distinguish whether autistic children are complicated with ID, and the accuracy of SVM is the highest (0.836); SVM and XGBoost have better accuracy (0.800, 0.838); LR has the best sensitivity (0.939), followed by SVM (0.952). Regarding specificity, SVM, RF, and XGBoost performed significantly higher than LR (0.355). The AUC of ML (SVM, 0.835 [95% CI: 0.747-0.944]; RF, 0.829 [95% CI: 0.738-0.920]; XGBoost, 0.845 [95% CI: 0.734-0.937]) is not different from traditional LR (0.858 [95% CI: 0.770-0.944]). Only SVM observed a good calibration degree. Regarding DCA, LR, and SVM have higher benefits in a wider threshold range. Conclusion: Compared to the traditional regression model, ML model based on socio-demographic and behavioral observation data, especially SVM, has a better ability to distinguish whether autistic children are combined with ID.

7.
BMC Geriatr ; 22(1): 741, 2022 09 12.
Artigo em Inglês | MEDLINE | ID: mdl-36096760

RESUMO

BACKGROUND: Although multimorbidity is a risk factor for disability, the relationship between the accumulative patterns of multimorbidity and disability remains poorly understood. The objective of this study was to identify the latent groups of multimorbidity trajectories among mid to older age adults and to examine their associations with incident disability. METHODS: We included 5,548 participants aged ≥ 45 years who participated in the China Health and Retirement Longitudinal Study from 2011 to 2018 and had no multimorbidity (≥ 2 chronic conditions) at baseline. The group-based multi-trajectory modeling was used to identify distinct trajectory groups of multimorbidity based on the latent dimensions underlying 13 chronic conditions. The association between multimorbidity trajectories and incident disability was analyzed using the generalized estimating equation model adjusting for potential confounders. RESULTS: Of the 5,548 participants included in the current analysis, 2,407 (43.39%) developed multimorbidity during the follow-up. Among participants with new-onset multimorbidity, four trajectory groups were identified according to the combination of newly diagnosed diseases: "Cardiometabolic" (N = 821, 34.11%), "Digestive-arthritic" (N = 753, 31.28%), "Cardiometabolic/Brain" (N = 618, 25.68%), and "Respiratory" (N = 215, 8.93%). Compared to participants who did not develop multimorbidity, the risk of incident disability was most significantly increased in the "Cardiometabolic/Brain" trajectory group (OR = 2.05, 95% CI: 1.55-2.70), followed by the "Cardiometabolic" (OR = 1.96, 95% CI: 1.52 -2.53) and "Digestive-arthritic" (OR = 1.70, 95% CI: 1.31-2.20) trajectory groups. CONCLUSIONS: The growing burden of multimorbidity, especially the comorbid of cardiometabolic and brain diseases, may be associated with a significantly increased risk of disability for mid to older age adults. These findings improve our understanding of multimorbidity patterns that affect the independence of living and inform the development of strategies for the primary prevention of disability.


Assuntos
Multimorbidade , Aposentadoria , Idoso , China/epidemiologia , Doença Crônica , Humanos , Estudos Longitudinais
8.
Front Psychiatry ; 13: 960672, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36090350

RESUMO

The prevalence of neurodevelopment disorders (NDDs) among children has been on the rise. This has affected the health and social life of children. This condition has also imposed a huge economic burden on families and health care systems. Currently, it is difficult to perform early diagnosis of NDDs, which results in delayed intervention. For this reason, patients with NDDs have a prognosis. In recent years, machine learning (ML) technology, which integrates artificial intelligence technology and medicine, has been applied in the early detection and prediction of diseases based on data mining. This paper reviews the progress made in the application of ML in the diagnosis and treatment of NDDs in children based on supervised and unsupervised learning tools. The data reviewed here provide new perspectives on early diagnosis and treatment of NDDs.

9.
Ecotoxicol Environ Saf ; 242: 113856, 2022 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-35809392

RESUMO

Arsenic (As) and lead (Pb) are frequently emitted from various sources into environment, but microbial responses to their combined toxicity have not been systematically investigated. In this study, Chlamydomonas reinhardtii was exposed to two levels of arsenate (As (V), 50, 500 µg/L), Pb (II) (500, 5000 µg/L) and their mixture (50 µg/L As (V) + 500 µg/L Pb (II); 500 µg/L As (V) + 5000 µg/L Pb (II)). The growth of C. reinhardtii was inhibited more remarkably by As (V) than by Pb (II). The As stress was alleviated by Pb in the 50 µg/L As (V) + 500 µg/L Pb (II) treatment, but was enhanced upon the 500 µg/L As (V) + 5000 µg/L Pb (II) exposure, with more pronounced changes in a number of physiological parameters of the algal cells. Proteomic results showed that 71 differently expressed proteins (DEPs) in the treatment of 50 µg/L As (V) + 500 µg/L Pb (II), and 167 DEPs were identified in that of 500 µg/L As (V) + 5000 µg/L Pb (II). These proteins were involved in energy metabolism, photosynthetic carbon fixation, reactive oxygen scavenging and defense, and amino acid synthesis. Taken together, these physiological and proteomic data demonstrated that C. reinhardtii could resist the As (V) and Pb (II) combined treatments through extracellular complexation and intracellular pathways.


Assuntos
Arsênio , Chlamydomonas reinhardtii , Arseniatos/metabolismo , Arseniatos/toxicidade , Arsênio/metabolismo , Chlamydomonas reinhardtii/metabolismo , Chumbo/metabolismo , Chumbo/toxicidade , Proteômica/métodos
10.
Psychiatry Res ; 310: 114434, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35172247

RESUMO

OBJECTIVES: This study aimed to explore the long-term cognitive trajectories and its' determinants, and construct prediction models for identifying high-risk populations with unfavorable cognitive trajectories. METHODS: This study included 3502 older adults aged 65-105 years at their first observations in a 16-year longitudinal cohort study. Cognitive function was measured by the Chinese version Mini Mental State Examination. The heterogeneity of cognitive function was identified through mixed growth model. Machine learning algorithms, namely regularized logistic regression (r-LR), support vector machine (SVM), random forest (RF), and super learner (SL) were used to predict cognitive trajectories. Discrimination and calibration metrics were used for performance evaluation. RESULTS: Two distinct trajectories were identified according to the changes of MMSE scores: intact cognitive functioning (93.6%), and dementia (6.4%). Older age, female gender, Han ethnicity, having no schooling, rural residents, low-frequency leisure activities, and low baseline BADL score were associated with a rapid decline in cognitive function. r-LR, SVM, and SL performed well in predicting cognitive trajectories (Sensitivity: 0.73, G-mean: 0.65). Age and psychological well-being were key predictors. CONCLUSION: Two cognitive trajectories were identified among older Chinese, and the identified key factors could be targeted for constructing early risk prediction models.


Assuntos
Cognição , Disfunção Cognitiva , Idoso , China/epidemiologia , Disfunção Cognitiva/diagnóstico , Feminino , Humanos , Estudos Longitudinais , Aprendizado de Máquina , Testes de Estado Mental e Demência
11.
Ecotoxicol Environ Saf ; 229: 113091, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34922168

RESUMO

Polysaccharides supply energy for various metabolic processes in cells. However, their roles in the arsenate (As(V)) resistance in microalgae remain largely unknown. Here, we explored the synthesis and transformation of polysaccharides in Chlamydomonas reinhardtii upon various levels of As(V) stress, using a number of physiological indexes along with transmission electron microscopic (TEM) and proteomic analyses. When exposed to low concentration of As(V) (0-20 µg/L), C. reinhardtii accumulated starch and produced more extracellular polysaccharides. At 50 µg/L As(V) treatment, starch accumulation gradually shifted to polysaccharides decomposition in the algal cells. Under higher As(V) concentration (500 µg/L), significantly more proteins in fatty acid metabolic pathway were differentially expressed, indicating that cells redirected carbon flux and transformed lipids into polysaccharides. The findings of this study demonstrate that polysaccharides may be critically involved in the As(V) resistance of C. reinhardtii.


Assuntos
Chlamydomonas reinhardtii , Microalgas , Arseniatos/toxicidade , Proteômica , Amido
12.
Environ Int ; 141: 105795, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32413623

RESUMO

Alpine ecosystems worldwide are characterized with high soil organic carbon (C) and low mineral nitrogen (N). Climate warming has been predicted to stimulate microbial decomposition and N mineralization in these systems. However, experimental results are highly variable, and the underlying mechanisms remain unclear. We examined the effects of warming, N input, and their combination on soil N pools and N-cycling microbes in a field manipulation experiment. Special attention was directed to the ammonia-oxidizing bacteria and archaea, and their mediated N-cycling processes (transformation rates and N2O emissions) in the third plant growing season after the treatments were initiated. Nitrogen input (12 g m-2 y-1) alone significantly increased soil mineral N pools and plant N uptake, and stimulated the growth of AOB and N2O emissions in the late growing season. While warming (by 1.4 °C air temperature) alone did not have significant effects on most parameters, it amplified the effects of N input on soil N concentrations and AOB abundance, eliciting a chain reaction that increased nitrification potential (+83%), soil NO3--N (+200%), and N2O emissions (+412%) across the whole season. Also, N input reduced AOB diversity but increased the dominance of genus Nitrosospira within the AOB community, corresponding to the increased N2O emissions. These results showed that a small temperature increase in soil may significantly enhance N losses through NO3- leaching and N2O emissions when mineral N becomes available. These findings suggest that interactions among global change factors may predominantly affect ammonia-oxidizing microbes and their mediated N-cycling processes in alpine ecosystems under future climate change scenarios.


Assuntos
Microbiologia do Solo , Solo , Carbono , Ecossistema , Pradaria , Nitrogênio , Tibet
13.
Ecotoxicol Environ Saf ; 194: 110441, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32155484

RESUMO

Vesicles (Ves) within fungal cells are the critical linkage between intracellular and extracellular systems. This study explored the application of Pb2+ to probe the physiology of intracellular Ves in Rhodotorula mucilaginosa (Rho). At low Pb2+ levels (0-500 mg/L), there was no evident change in the content of extracellular polymeric substances (EPS) or microbial activity. At medium-high levels (1000-2000 mg/L), the sizes of Ves within the Rho cells were significantly enlarged, with abundant lead nano-particles (Pb NPs) formed either on the cell surface or interior, whereas the EPS content and bioactivity were still stable. At a high level (2500 mg/L), the Rho cells were severely deformed, with cell counts reduced by more than 99%. However, the EPS contents and the respiration rate of the surviving cells dramatically increased to the maximum values (i.e., 1785 mg/1010 cells and 37 mg C 10-10 cells h-1, respectively). The Ves surface adsorbed Pb cations with higher density, compared with the cell membrane. Moreover, fusion of some Ves to the membrane (functioning in transport) was observed under transmission electron microscope (TEM). Three pathways of detoxification via intracellular Ves were finally proposed, i.e., Ve-mediated transport (from intracellular to extracellular) of EPS components, absorption of Pb NPs on the Ve surface, and accumulation of Pb NPs within Ves. This study sheds light on the possibility of exploring microbial physiology via Pb2+ cations.


Assuntos
Substâncias Perigosas/toxicidade , Chumbo/toxicidade , Rhodotorula/fisiologia , Adsorção , Cátions , Testes de Toxicidade
14.
Sci Total Environ ; 704: 135450, 2020 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-31896220

RESUMO

Many high-elevation alpine ecosystems have been experiencing significant increases in air temperature and, to a lesser extent, nitrogen (N) deposition. These changes may affect N-cycling microbes and enhance emissions of nitrous oxide (N2O, a potent greenhouse gas) from soil. However, few studies have investigated whether and how the resulting changes in N-cycling microbes may affect the temperature sensitivity (Q10) of N2O emission and in turn feed back to N2O emissions. We conducted two incubation experiments to examine N2O emissions and their temperature sensitivities in soils that had experienced 3-yr field treatments of warming, N inputs and their combination in a Tibetan alpine meadow. Our results showed that neither N inputs nor warming alone affected the rate or Q10 of soil N2O emission, but combining the two significantly increased both parameters. Also, combined N and warming significantly increased the abundance of ammonia-oxidizing bacteria (AOB), corresponding with high soil N2O emission. In addition, N2O emission from nitrification accounted for 60-80% of total emissions in all soils, indicating that nitrifying microbes dominated the N2O production and its temperature sensitivity. Using random forest (RF) and structural equation model (SEM) analyses, we further evaluated the effects of various soil characteristics on soil N2O emissions and Q10. We identified soil moisture, pH, N mineralization and AOB abundance as the main predictors of the Q10 of N2O emissions. Together, these findings suggest that alterations in soil moisture, pH and ammonia-oxidizing bacteria induced by long-term N inputs and warming may increase temperature sensitivity of soil N2O emissions, leading to a positive climate feedback in this high-altitude alpine ecosystem.

15.
Environ Microbiol ; 22(4): 1507-1516, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31215728

RESUMO

Successful application of microorganisms to heavy metal remediation depends on their resistance to toxic metals. This study contrasted the differences of tolerant mechanisms between Pb2+ and Cd2+ in Enterobacter sp. Microbial respiration and production of formic acid showed that Enterobacter sp. had a higher tolerant concentration of Pb (>1000 mg l-1 ) than Cd (about 200 mg l-1 ). Additionally, SEM confirmed that most of Pb and Cd nanoparticles (NPs) were adsorbed onto cell membrane. The Cd stress, even at low concentration (50 mg l-1 ), significantly enlarged the sizes of cells. The cellular size raised from 0.4 × 1.0 to 0.9 × 1.6 µm on average, inducing a platelet-like shape. In contrast, Pb cations did not stimulate such enlargement even up to 1000 mg l-1 . Moreover, Cd NPs were adsorbed homogeneously by almost all the bacterial cells under TEM. However, only a few cells work as 'hot spots' on the sorption of Pb NPs. The heterogeneous sorption might result from a 'self-sacrifice' mechanism, i.e., some cells at a special life stage contributed mostly to Pb sorption. This mechanism, together with the lower mobility of Pb cations, caused higher microbial tolerance and removal efficiency towards Pb2+ . This study sheds evident contrasts of bacterial resistance to the two most common heavy metals.


Assuntos
Cádmio/toxicidade , Enterobacter/efeitos dos fármacos , Chumbo/toxicidade , Nanopartículas Metálicas/toxicidade , Adsorção , Cádmio/química , Membrana Celular/química , Tamanho Celular/efeitos dos fármacos , Enterobacter/química , Enterobacter/metabolismo , Enterobacter/ultraestrutura , Formiatos/metabolismo , Chumbo/química , Nanopartículas Metálicas/química , Microscopia Eletrônica de Transmissão , Estresse Fisiológico
16.
Ecotoxicol Environ Saf ; 174: 484-490, 2019 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-30856560

RESUMO

Microorganisms have been widely applied to heavy metal adsorption due to their strong secretion of extracellular polymeric substances (EPS). This study explored the responses of Rhodotorula mucilaginosa (R1, a red yeast with substantial EPS supply) under Pb stress. The maximum sorption of Pb cations by R1 was ~650 mg/L. In particular, despite the declined microbial biomass, the total Pb sorption after incubation was actually elevated in the solution with high Pb concentration. At 0-1000 mg/L Pb(NO3)2 level, the longitudinal sizes of the yeast capsules increased from 2.04 to 2.90 µm. At 1500 mg/L, however, the survived yeast started to lose the membrane integrity of the cells. Meanwhile, the percentages of organic carbon contents of EPS decreased from 40% to 33% when the Pb(NO3)2 concentration raised to 2500 mg/L, confirming the incorporation of Pb2+ cations into the fungal EPS during the sorption. For the survived R1 cells, function of polysaccharides to resist Pb toxicity only worked at extremely high Pb(NO3)2 levels (>= 1500 mg/L). In contrast, proteins showed continuously enhanced ability to resist Pb toxicity, consistent with their increasing content (per cell) in the EPS. Moreover, ATR-IR spectra showed that the intensity of amide II peak at 1540 cm-1 was significantly increased, indicating elevated glutathione (GSH) in EPS. This suggested that GSH could be the critical Pb-binding component in EPS proteins. This study hence elucidated roles of polysaccharides and proteins in EPS under the toxicity caused by heavy metals.


Assuntos
Poluentes Ambientais/toxicidade , Matriz Extracelular de Substâncias Poliméricas/metabolismo , Proteínas Fúngicas/metabolismo , Chumbo/toxicidade , Polissacarídeos/metabolismo , Rhodotorula/efeitos dos fármacos , Adsorção , Biomassa , Poluentes Ambientais/metabolismo , Chumbo/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Rhodotorula/crescimento & desenvolvimento , Rhodotorula/metabolismo , Rhodotorula/ultraestrutura
17.
Environ Microbiol ; 21(1): 471-479, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30421848

RESUMO

Environmental microorganisms have been widely applied in heavy metal remediation. This study explored the mechanisms of lead tolerance of two typical filamentous fungi, Aspergillus niger and Penicillium oxalicum. It is shown that the mechanisms of reducing Pb toxicity by these two fungi have three major pathways. The secreted oxalic acid can react with Pb (II) to form insoluble Pb minerals, primarily lead oxalate. Then, the enhanced biosorption via forming new border of cell wall prevents the transportation of Pb (II) into hypha. In addition, the fungal activity could be maintained even at high Pb concentration due to the intracellular accumulation. It was confirmed that A. niger has the higher Pb tolerance (up to 1500 mg l-1 Pb level) compared with P. oxalicum (up to 1000 mg l-1 ). Meanwhile, Pb levels below 1000 mg l-1 partially stimulate the bioactivity of A. niger, which was confirmed by its elevated respiration (from 53 to 63 mg C l-1 medium h-1 ). This subsequently enhanced microbial functions of A. niger to resist Pb toxicity. A better understanding of Pb tolerance of these two fungi sheds a bright future of applying them to remediate lead-contaminated environments.


Assuntos
Aspergillus niger/metabolismo , Biodegradação Ambiental , Chumbo/toxicidade , Ácido Oxálico/metabolismo , Penicillium/metabolismo , Aspergillus niger/efeitos dos fármacos , Minerais/metabolismo , Oxalatos/metabolismo , Penicillium/efeitos dos fármacos
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