The CO
2
electrochemical reduction reaction (CO
2
RR) has been a promising conversion method for CO
2
utilization. Currently, the lack of electrocatalysts with favorable stability and high efficiency ...hindered the development of CO
2
RR. Nitrogen-doped graphene nanocarbons have great promise in replacing metal catalysts for catalyzing CO
2
RR. By using the density functional theory (DFT) method, the catalytic mechanism and activity of CO
2
RR on 11 types of nitrogen-doped graphene have been explored. The free energy analysis reveals that the zigzag pyridinic N- and zigzag graphitic N-doped graphene possess outstanding catalytic activity and selectivity for HCOOH production with an energy barrier of 0.38 and 0.39 eV, respectively. CO is a competitive product since its free energy lies only about 0.20 eV above HCOOH. The minor product is CH
3
OH and CH
4
for the zigzag pyridinic N-doped graphene and HCHO for zigzag graphitic N-doped graphene, respectively. However, for Z-pyN, CO
2
RR is passivated by too strong HER. Meanwhile, by modifying the pH value of the electrolyte, Z-GN could be selected as a promising nonmetal electrocatalyst for CO
2
RR in generating HCOOH.
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•Mining activity of realgar ore resulted in co-contamination of As and Sb.•Mining activity also influenced microbial structure and metabolic potentials.•As and Sb co-contamination ...enriched some As- and Sb-resistant bacteria.•The contamination affected As-related genes, and others about C, N, and S cycling.
Microorganisms can mediate arsenic (As) and antimony (Sb) transformation and thus change the As and Sb toxicity and mobility. The influence of As and Sb on the innate microbiome has been extensively characterized. However, how microbial metabolic potentials are influenced by the As and Sb co-contamination is still ambiguous. In this study, we selected two contrasting sites located in the Shimen realgar mine, the largest realgar mine in Asia, to explore the adaptability and response of the soil microbiome to As and Sb co-contamination and the impact of co-contamination on microbial metabolic potentials. It is observed that the geochemical parameters, including the As and Sb fractions, were the driving forces that reshaped the community composition and metabolic potentials. Bacteria associated with Bradyrhizobium, Nocardioides, Sphingomonas, Burkholderia, and Streptomyces were predicted to be tolerant to high concentrations of As and Sb. Co-occurrence network analysis revealed that the genes related to C fixation, nitrate/nitrite reduction, N fixation, and sulfate reduction were positively correlated with the As and Sb fractions, suggesting that As and Sb biogeochemical cycling may interact with and benefit from C, N, and S cycling. The results suggest that As and Sb co-contamination not only influences As-related genes, but also influences other genes correlated with microbial C, N, and S cycling.
Anaerobic toluene-degrading enrichment cultures inoculated from gasoline-contaminated soil were maintained for more than 3 years, using toluene as the carbon source and CO
2
as electron acceptor. ...A large amount of methane was produced and toluene biodegradation was observed from these enrichment cultures, indicating that methanogenic toluene biodegradation may occur in these cultures. Furthermore, DNA-SIP was used to identify toluene-degrading bacteria in these methanogenic enrichment cultures. The current SIP experiments indicated that bacteria in the phylum
Proteobacteria
(genus
Pseudomonas
) may be the dominant toluene-degrading bacteria under the methanogenic conditions. In addition, bacteria related to the
Simplicispira
were also associated with the anaerobic toluene biodegradation, but may not be the primary toluene-degrading bacteria. The identification of novel toluene degraders expands current knowledge regarding the potential fate of toluene under methanogenic conditions.
Acid mine drainage (AMD) is harmful to the environment and human health. Microorganisms-mineral interactions are responsible for AMD generation but can also remediate AMD contamination. Understanding ...the microbial response to AMD irrigation will reveal microbial survival strategies and provide approaches for AMD remediation. A terrace with sharp geochemical gradients caused by AMD flooding were selected to study the microbial response to changes in environmental parameters related to AMD contamination. AMD intrusion reduced soil microbial community diversity and further changed phylogenetic clustering patterns along the terrace gradient. We observed several genera seldom reported in AMD-related environments (i.e., Corynebacterium, Ochrobactrum, Natronomonas), suggesting flexible survival strategies such as nitrogen fixation, despite the poor nutritional environment. A co-occurrence network of heavily-contaminated fields was densely connected. The phyla Proteobacteria, Acidobacteria, Chloroflexi, and Euryarchaeota were all highly interconnected members, which may affect the formation of AMD. Detailed microbial response to different soil characterizations were highlighted by random forest model. Results revealed the top three parameters influencing the microbial diversity and interactions were pH, Fe(III), and sulfate. Various acidophilic Fe- and S-metabolizing bacteria were enriched in the lower fields, which were heavily contaminated by AMD, and more neutrophiles prevailed in the less-contaminated upper fields. Many indicator species in the lower fields were identified, including Desulfosporosinus, Thermogymnomonas, Corynebacterium, Shewanella, Acidiphilium, Ochrobactrum, Leptospirillum, and Allobaculum, representing acid-tolerant bacteria community in relevant environment. The detection of one known sulfate-reducing bacteria (i.e., Desulfosporosinus) suggested that biotic sulfate reduction may occur in acidic samples, which offers multiple advantages to AMD contamination treatment. Collectively, results suggested that the geochemical gradients substantially altered the soil microbiota and enriched the relevant microorganisms adapted to the different conditions. These findings provide mechanistic insights into the effects of contamination on the soil microbiota and establish a basis for in situ AMD bioremediation strategies.
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•A terrace with sharp geochemical gradients caused by AMD flooding were selected.•AMD intrusion reduced soil microbial community diversity and phylogenetic interactions.•Microbe showed flexible survival strategies in the poor nutritional environment.•pH, Fe(III), and sulfate were main factors influencing the soil microbial community.•Many acid-tolerant microorganisms were identified in the heavily contaminated fields.
This work revealed the soil microbial community diversity and phylogenetic interactions in response to the terrace gradient irrigated by AMD irrigation.
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•Unique terrace with sharp geochemical gradients contaminated by AMD was selected.•Microbial communities and metabolisms in various geochemical gradients were compared.•AMD ...contamination impaired processes such as nitrogen fixation and DNRA.•pH, TOC, Fe- and S-species were identified as drivers for community and metabolism.
A unique terrace with sharp gradient of environmental conditions was selected to study the microbial response and survival strategies to the extreme environments introduced by acid mine drainage (AMD) contamination. A combination of geochemical analyses, metagenomic sequencing, ex-situ microcosm setups, and statistical analyses were used to investigate the environment-microbe interactions. The microbial communities and metabolic potentials along the terrace were studied by focusing on the genes associated with important biogeochemical processes (i.e., C, N, S cycling and metal resistance). Results show that the variations of geochemical parameters substantially shaped the indigenous microbial communities. Sharp environmental gradients also impacted the microbial metabolic potentials, especially for C, N, and S cycling. Although the relative abundances of carbon fixing genes did not significantly vary along the environmental gradients, the taxa for carbon fixation varied significantly in more contaminated fields versus less contaminated fields, indicating the effects of AMD contamination on the autotrophic microbial communities. AMD input also influenced the N cycling, especially for nitrogen fixation and dissimilatory nitrate reduction to ammonium (DNRA). In addition, ex situ experiments were undertaken to evaluate the effects of AMD contamination on nitrogen fixation rates. Random Forest (RF) analysis indicated that nitrate, pH, total N, TOC exhibited positive correlations with the rates of nitrogen fixation while total Fe, Fe(III), and sulfate showed negative effects. Two co-occurrence networks at taxonomic and genomic levels indicated that geochemical parameters such as pH, TOC, total N, total S, and total Fe substantially influenced the innate microbial communities and their metabolic potentials. The current study provides an understanding for microbial response to AMD contamination and lays the foundation for future potential AMD bioremediation.
The extensive application of perfluoroalkyl and polyfluoroalkyl substances (PFASs) causes their frequent detection in various environments. In this work, two typical PFASs, perfluorooctanoic acid ...(PFOA) and perfluorooctanesulfonic acid (PFOS), are selected to investigate their effects on soil microorganisms. Microbial community structure and microbe–microbe relationships were investigated by high-throughput sequencing and co-occurrence network analysis. Under 90 days of exposure, the alpha-diversity of soil microbial communities was increased with the PFOS treatment, followed by the PFOA treatment. The exposure of PFASs substantially changed the compositions of soil microbial communities, leading to the enrichment of more PFASs-tolerant bacteria, such as Proteobacteria,
Burkholderiales
, and
Rhodocyclales
. Comparative co-occurrence networks were constructed to investigate the microbe–microbe interactions under different PFASs treatments. The majority of nodes in the PFOA and PFOS networks were associated with the genus
Azospirillum
and
Hydrogenophaga
, respectively. The LEfSe analysis further identified a set of biomarkers in the soil microbial communities, such as
Azospirillum
,
Methyloversatilis
,
Hydrogenophaga
,
Pseudoxanthomonas
, and
Fusibacter
. The relative abundances of these biomarkers were also changed by different PFASs treatments. Functional gene prediction suggested that the microbial metabolism processes, such as nucleotide transport and metabolism, cell motility, carbohydrate transport and metabolism, energy production and conversion, and secondary metabolites biosynthesis transport and catabolism, might be inhibited under PFAS exposure, which may further affect soil ecological services.
Antimony (Sb) contamination is a growing environmental concern due to the increasing use of this metalloid in mining and industrial activities. The remediation of Sb-contaminated soil is a lengthy ...and costly process. Phytoremediation has been suggested as a cost-effective method for the long-term management of Sb-contaminated sites. Various plant types have been found to thrive in contaminated sites and have the potential to remediate Sb contamination; however, their impacts on Sb speciation and the indigenous microbial community remain unclear. In the current study, soils from three types of vegetation environment (i.e., grass, forest, and agricultural) were collected from two Sb mining areas in Guizhou, China. Comparisons of geochemical and microbiological properties among the three vegetation types revealed that vegetation was a major driver of soil biogeochemical characteristics. Contaminant fractions (i.e., extractable fractions of Sb and As) had a greater influence on microbial communities in grass and forest soil, whereas pH had a greater impact in agricultural soil. This difference may indicate distinct microbe–environment interactions in agricultural soil affected by anthropogenic activity. The dominant taxa, including Flavobacterium, Geobacter, Janthinobacterium, Clostridium, and Mycobacterium responded positively to various contaminant fractions, indicating that the community had adapted to the chronically contaminated environment. However, the regulation of these dominant genera by geochemical properties appears to be taxon-specific. Our results demonstrate that vegetation type has a substantial impact on Sb and As biogeochemical cycles, and should be considered in future remediation efforts.
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•Vegetation cover impacts indigenous soil microbial-environment interactions.•A group of core microbiome exist regardless of the soil vegetation type.•Sb and As demonstrated distinct impacts on the soil microbial community diversity.•Microbial responses to Sb and As contaminants were taxon-specific.
A series of V2O5/CeO2 catalysts with different potassium loadings were prepared to investigate alkali deactivations for selective catalytic reduction of NOx with NH3. An alkali poisoning mechanism ...could be attributed to surface acidity, reducibility, and NOx adsorption/desorption behaviors. The detailed factors are as follows: (1) decrease of surface acidity suppresses NH3 adsorption by strong bonding of alkali to vanadia (major factor); (2) low reducibility prohibits NH3 activation and NO oxidation by formation bonding of alkali to vanadia and ceria (important factor); (3) active NOx(-) species at low temperature diminish because of coverage of alkali on the surfaces (minor factor); and (4) stable, inactive nitrate species at high temperature increase by generating new basic sites (important factor).
Antimony (Sb) contamination released from mine tailings represents a global threat to natural ecosystems and human health. The geochemical conditions of Sb tailings, which are oligotrophic and ...replete in sulfur (S) and Sb, may promote the coupled metabolism of Sb and S. In this study, multiple lines of evidence indicate that a novel biogeochemical process, S oxidation coupled to Sb(V) reduction, is enzymatically mediated by Desulfurivibrio spp. The distribution of Desulfurivibrio covaried with S and Sb concentrations, showing a high relative abundance in Sb mine tailings but not in samples from surrounding sites (i.e., soils, paddies, and river sediments). Further, the metabolic potential to couple S oxidation to Sb(V) reduction, encoded by a non-canonical, oxidative sulfite reductase (dsr) and arsenate reductase (arrA) or antimonate reductase (anrA), respectively, was found to be common in Desulfurivibrio genomes retrieved from metal-contaminated sites in southern China. Elucidation of enzymatically-catalyzed S oxidation coupled to Sb(V) reduction expands the fundamental understanding of Sb biogeochemical cycling, which may be harnessed to improve remediation strategies for Sb mine tailings.
Purpose:
Serum markers with increased sensitivity and specificity for endometrial cancer are required. To date, no good marker has met this standard. The aims of our study were to evaluate the ...utility of tumor markers HE4, CA125, CA724, and CA19-9 as potential markers in patients diagnosed with endometrial cancer.
Methods:
Blood samples from 105 patients with endometrial cancer and 87 healthy women were analyzed by Roche electrochemiluminescent immunoassay, and serum values were measured for the following biomarkers: HE4, CA125, CA724, and CA19-9.
Results:
Serum HE4, CA125, CA724, and CA19-9 concentrations were significantly higher in patients with endometrial cancer, compared with controls (P < .001). In the receiver operating characteristic analysis, the area under the curve value for combination of HE4, CA125, CA724, and CA19-9 was 82.1% (95% confidence interval: 75.3%-86.2%), the maximum area of the test groups. For all stages of patients with endometrial cancer, HE4 had higher sensitivity (58%), positive predictive value (60%), and negative predictive value (67%) than any other single tumor marker, and in the combination of HE4, CA125, CA724, and CA19-9, the sensitivity and positive predictive values reached 59.1% and 88%, respectively. Meanwhile, the receiver operating characteristic area under the curve of the combination of the 4 markers was significantly increased than any other group, either in stage I or in stage II to IV cases. HE4 and CA125 both correlate with advanced age; in addition, HE4 was related to pathology subtypes and positive adnexal involvement, CA125 was related to International Federation of Gynecology and Obstetrics stage, CA19-9 was related to International Federation of Gynecology and Obstetrics stage, and CA724 was correlated with positive lymph node.
Conclusion:
Combination of HE4, CA125, CA724, and CA19-9 has the highest value in diagnosing endometrial cancer, and they can be a useful tissue immune marker for patients with endometrial cancer.
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