Display omitted
•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.
Display omitted
•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.
SMD is designed into many MCM/SiP products, but accurate EM simulation of SMD in a design has been a challenge. In fact, circuit simulation with an EM MCM model connected with vendor-provided SMT ...models often leads to a shift of harmonic trap notch. Such shift may be attributed to the intrinsic inductance of an EM port. In this paper, we focus on EM models of HFSS, present discovery of intrinsic port inductance in an HFSS model and discuss issues and techniques on how to handle lumped SMT ports in an HFSS EM model for more accurate SMD circuit simulation.
Display omitted
•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.
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.
Display omitted
•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.
Aiming at the requirement of the load conversion in aeronautics and astronautics static strength analysis, a three-dimensional aerodynamic load equivalent distribution method based on least squares ...is proposed. Based on the principle of the closest distance, the corresponding relationship between the aerodynamic node and the finite element node is established to ensure that each finite element node has its corresponding aerodynamic node. Under the requirement of minimizing the variance of load obtained by each node allocation, the least squares algorithm is used to obtain the results of the load conversion. Through an engineering example of aerodynamic distribution, it is verified that the method presented in this paper not only has high accuracy but also can ensure the uniformity of load distribution before and after load distribution.
Antibiotic resistance is a global challenge and represents a growing threat on human health worldwide. Wastewater treatment plants (WWTPs) are generally considered as hotspots for control and/or ...dissemination of antibiotic resistance. The role of antibiotics, antibacterial residues, and heavy metals played on the evolution and spread of antibiotic resistance is still not well understood. Here, the occurrence of antibiotics (i.e., macrolides, tetracyclines, sulfonamides, and quinolones), antibacterial residues (i.e., triclosan), as well as heavy metals (i.e., cadmium, chromium, copper, zinc, lead, and nickel) in urban wastewater was investigated. Also, the abundances of erythromycin resistance genes (ERY-ARGs) including ere(A), ere(B), mef(A)/mef(E), erm(A), erm(B), erm(C), and msr(A)/msr(B) genes were screened. A relationship between certain antibiotics, antibacterial residues, and heavy metals and ERY-ARGs was demonstrated. ERY presented significant correlations (0.883 < r < 0.929, P < 0.05) with ere(A), ere(B), and mef(A)/mef(E) genes, while tetracycline exhibited a significant correlation (r = 0.829, P < 0.05) with erm(B) genes. It is noteworthy that triclosan correlated significantly (0.859 < r < 0.956, P < 0.05) with ere(A), ere(B), mef(A)/mef(E), and erm(B) genes. In addition, significantly positive correlations (0.823 < r < 0.871, P < 0.05) were observed between zinc and lead and certain ERY-ARGs (i.e., ere(B), mef(A)/mef(E), erm(B), etc.). Further investigations should be involved to elucidate the co-selection and/or cross-selection mechanisms due to co-existence of these selective factors in urban wastewater.
Rice paddies are a significant source of the greenhouse gas methane, which mainly originates from microbial activity. Methane generation in anaerobic systems involves complex interactions of multiple ...functional microbial groups. Rice paddies installed in hilly terrain are often terraced, providing multiple quasi-independent plots differing primarily in their elevation up a hillside. This represents an excellent study site to explore the influence of environmental factors on microbial communities and interactions among microbial populations. In this study, we used a combination of geochemical analyses, high-throughput amplicon sequencing, and statistical methods to elucidate these interactions. Sulfate, total nitrogen, total iron, and total organic carbon were determined to be critical factors in steering the ecosystem composition and function. Sulfate-reducing bacteria predominated in the rice terrace microbial communities, and Fe(III)-reducing and methane-oxidizing bacteria were abundant as well. Biotic interactions indicated by co-occurrence network analysis suggest mutualistic interactions among these three functional groups. Paddy-scale methane production may be affected by competition among methanogens and sulfate- and Fe(III)-reducing bacteria, or by direct methane oxidation by methane-oxidizing bacteria.
Microbial communities were characterized in rice terrace. The environment- and microbe-microbe interactions indicated the mitigation of sulfate and Fe on methane production.
Display omitted
•Microbial communities were characterized in rice paddy terrace.•Sulfate may impact the innate microbiota and mitigate methane.•Dynamic biotic interactions occurred in the paddy soils.•Co-occurring of MOB and SRB/FeRB suggested associated communities.
Thallium (Tl) is a highly toxic metalloid and is considered a priority pollutant by the US Environmental Protection Agency (EPA). Currently, few studies have investigated the distribution patterns of ...bacterial and fungal microbiomes in Tl-impacted environments. In this study, we used high-throughput sequencing to assess the bacterial and fungal profiles along a gradient of Tl contents in Tl mine waste rocks in southwestern China. Our results showed that Tl had an important, but different influence on the bacterial and fungal diversity indices. Using linear regression analysis, we furtherly divided the dominant bacterial and fungal groups into three distinct microbial sub-communities thriving at high, moderate, and low levels of Tl. Furthermore, our results also showed that Tl is also an important environmental variable that regulates the distribution patterns of ecological clusters and indicator genera. Interestingly, the microbial groups enriched in the samples with high Tl levels were mainly involved in metal and nutrient cycling. Taken together, our results have provided useful information about the responses of bacterial and fungal groups to Tl contamination.
Display omitted
•Thallium(Tl) regulates the bacterial diversity but has little impact on fungi.•Three sub-microbial communities are identified across a Tl content gradient.•Tl predicts the distribution patterns of ecological clusters and indicator genera.•Microbial groups in high Tl samples are involved in metal and nutrient cycling.
Thallium regulates the distribution patterns of bacterial and fungal groups which involved in metal(loid)s and nutrients cycling.
PDF
