scholarly journals Metagenomic insights into evolution of a heavy metal-contaminated groundwater microbial community

2010 ◽  
Vol 4 (5) ◽  
pp. 660-672 ◽  
Author(s):  
Christopher L Hemme ◽  
Ye Deng ◽  
Terry J Gentry ◽  
Matthew W Fields ◽  
Liyou Wu ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Microbial Community ◽  
Contaminated Groundwater

scholarly journals Lateral Gene Transfer in a Heavy Metal-Contaminated-Groundwater Microbial Community

mBio ◽  
2016 ◽  
Vol 7 (2) ◽  
Author(s):  
Christopher L. Hemme ◽  
Stefan J. Green ◽  
Lavanya Rishishwar ◽  
Om Prakash ◽  
Angelica Pettenato ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Microbial Community ◽  
Gene Transfer ◽  
Microbial Communities ◽  
Lateral Gene Transfer ◽  
Metal Contamination ◽  
Heavy Metal Contamination ◽  
Contaminated Groundwater ◽  
Rrna Gene ◽  
Changing Environments

ABSTRACT Unraveling the drivers controlling the response and adaptation of biological communities to environmental change, especially anthropogenic activities, is a central but poorly understood issue in ecology and evolution. Comparative genomics studies suggest that lateral gene transfer (LGT) is a major force driving microbial genome evolution, but its role in the evolution of microbial communities remains elusive. To delineate the importance of LGT in mediating the response of a groundwater microbial community to heavy metal contamination, representative Rhodanobacter reference genomes were sequenced and compared to shotgun metagenome sequences. 16S rRNA gene-based amplicon sequence analysis indicated that Rhodanobacter populations were highly abundant in contaminated wells with low pHs and high levels of nitrate and heavy metals but remained rare in the uncontaminated wells. Sequence comparisons revealed that multiple geochemically important genes, including genes encoding Fe 2+ /Pb 2+ permeases, most denitrification enzymes, and cytochrome c 553 , were native to Rhodanobacter and not subjected to LGT. In contrast, the Rhodanobacter pangenome contained a recombinational hot spot in which numerous metal resistance genes were subjected to LGT and/or duplication. In particular, Co 2+ /Zn 2+ /Cd 2+ efflux and mercuric resistance operon genes appeared to be highly mobile within Rhodanobacter populations. Evidence of multiple duplications of a mercuric resistance operon common to most Rhodanobacter strains was also observed. Collectively, our analyses indicated the importance of LGT during the evolution of groundwater microbial communities in response to heavy metal contamination, and a conceptual model was developed to display such adaptive evolutionary processes for explaining the extreme dominance of Rhodanobacter populations in the contaminated groundwater microbiome. IMPORTANCE Lateral gene transfer (LGT), along with positive selection and gene duplication, are the three main mechanisms that drive adaptive evolution of microbial genomes and communities, but their relative importance is unclear. Some recent studies suggested that LGT is a major adaptive mechanism for microbial populations in response to changing environments, and hence, it could also be critical in shaping microbial community structure. However, direct evidence of LGT and its rates in extant natural microbial communities in response to changing environments is still lacking. Our results presented in this study provide explicit evidence that LGT played a crucial role in driving the evolution of a groundwater microbial community in response to extreme heavy metal contamination. It appears that acquisition of genes critical for survival, growth, and reproduction via LGT is the most rapid and effective way to enable microorganisms and associated microbial communities to quickly adapt to abrupt harsh environmental stresses.

The Efficiency of Natural and Electrokinetic Enhanced Migration of Pb in Aquifer

2012 ◽  
Vol 253-255 ◽  
pp. 1098-1101
Author(s):  
Hong Tao Hu
Keyword(s):  
Heavy Metal ◽  
Removal Efficiency ◽  
Experimental Results ◽  
Contaminated Groundwater ◽  
Voltage Gradient ◽  
Migration Method ◽  
Variation Rule

The natural and electrokinetic enhanced migration method was studied by the experiments in groundwater contaminated by heavy metal Pb in this work. The experimental results showed that the variation rule of Pb reflected that its migration was weak and the removal efficiency was only 9.30% near the anode in the natural seepage condition, but under the enhanced migration and remediation function, the pollutants could be enriched and removed faster, thus the removal efficiency of Pb was 46.72% near the anode at the end of experiment when the experimental voltage gradient was 0.28V/cm, which made known that this electrokinetic enhanced migration of Pb in contaminated groundwater was more effective method than that of natural seepage migration and enhanced the removal of contaminant in aquifer.

scholarly journals Remediation of Cr(VI)/Cd(ІІ)-Contaminated Groundwater with Simulated Permeable Reaction Barriers Filled with Composite of Sodium Dodecyl Benzene Sulfonate-Modified Maifanite and Anhydride-Modified Fe@SiO2@Polyethyleneimine: Environmental Factors and Effectiveness

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Jingqing Gao ◽  
Yalin Zhai ◽  
Zhenzhen Huang ◽  
Peng Ren ◽  
Jianlei Gao ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Composite Material ◽  
Metal Removal ◽  
Heavy Metal Removal ◽  
Sodium Dodecyl ◽  
Sodium Dodecyl Benzene Sulfonate ◽  
Contaminated Groundwater ◽  
Column Experiments ◽  
Benzene Sulfonate ◽  
Dodecyl Benzene Sulfonate

A composite material of sodium dodecyl benzene sulfonate- (SDBS-) modified maifanite and anhydride-modified Fe@SiO2@PEI (PEI) was used as an adsorbent for the removal of hexavalent chromium (Cr(VI)) and bivalent cadmium (Cd(II)) from groundwater by using column experiments and simulated PRB test. In this study, the optimum proportion of SDBS-modified maifanite and anhydride-modified Fe@SiO2@PEI was 5 : 1. In the column experiments, it was found that the penetration time increased with the increase of the initial concentrations (30, 60, and 90 mg/L) and the decrease of the flow rates (5.45, 10.9, and 16.35 mL/min) at an influent pH of 6.5 ± 0.3 . It was also obtained that the removal rates of Cr(VI) and Cd(ІІ) reached 99.93% and 99.79% at an initial Cr(VI) and Cd(ІІ) concentration of 30 mg/L with the flow rate of 10.9 mL/min, respectively, at 6 h. Furthermore, excellent removal effectiveness of Cr(VI) and Cd(ІІ) (85.94% and 83.45%, respectively) was still achieved in simulated PRB test at a flow rate of 5.45 mL/min with the heavy metal solution concentration of 5.0 ± 0.5  mg/L (Cr(VI) and Cd(II) concentration were, respectively, 5.0 ± 0 . 5 mg/L); and the adsorbent had not completely failed by the end of the trial. Yoon-Nelson model was successfully applied to predict the breakthrough curves for the assessment of composite material heavy metal removal performance and was in good agreement with the experimental data of the heavy metal removal efficiency. The strong removal ability of the adsorbent could be attributed to the fact that maifanite with a large diameter can provide support and increase the permeability coefficient and porosity and that zero-valent iron (ZVI) can convert Cr(VI) to Cr(III) and improve the adsorption capacity of maifanite. The obtained results suggested that the novel PRB fillers have great significance for preventing and controlling Cr(VI)/Cd(ІІ)-contaminated groundwater.

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