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Research
High Arsenic Levels Increase Activity Rather Than Diversity or Abundance of Arsenic Metabolism Genes in Paddy Soils
Si-Yu Zhang
East China Normal University
Corresponding Author
ORCiD: https://orcid.org/0000-0001-6701-5790
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Background
Arsenic (As) is a toxic metalloid pervasively present in the environment. Microorganisms have evolved the capacity to metabolize As, and As metabolism genes are ubiquitously present in the environment even in the absence of high concentration of As. However, the As metabolism genes diversity, relative abundance, and transcriptional activity in response to different As levels remain unclear, limiting our understanding of the microbial activities that control the fate of an important environmental pollutant. To address this issue, we applied metagenomics and metatranscriptomics to paddy soils showing a gradient of As concentrations to investigate As resistance genes (ars), including arsR, acr3, arsB, arsC, arsM, arsI, arsP and arsH as well as energy-generating As respiratory oxidation (aioA) and reduction (arrA) genes.
Results
Somewhat unexpectedly, the relative DNA abundances and diversity of ars, aioA and arrA genes were not significantly different between low and high (~10 vs ~100 mg kg-1) As soils. By comparison to available metagenomes from other soils, geographic distance rather than As levels drove the different composition of microbial communities. Arsenic significantly increased ars genes abundance only when its concentration was higher than 410 mg kg -1. In contrast, between low and high (~10 vs ~100 mg kg-1) As soils, metatranscriptomics revealed a significant increase in transcription of ars and aioA genes, which are induced by arsenite, the dominant As species in paddy soils, but not arrA genes, which are induced by arsenate. Co-occurrence patterns of arsR, acr3, and arsM genes were revealed by network analysis corroborating that the arsR, acr3 and arsM genes are usually organized in a single ars operon. The transcriptome level response appeared to be community-wide as opposed to taxon-specific.
Conclusions
High As levels increased the activity of As metabolism genes rather than their abundance or diversity in paddy soils. These findings advance understanding of how microbes respond to high As levels and the diversity of As metabolism genes in paddy soils, and indicated that future studies of As metabolism in soil, and likely other environments, should include the function (transcriptome) level.
Keywords
Arsenic resistance genes, Arsenic respiratory genes, Abundance and diversity, Transcriptional activity, Network, Paddy soil
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This is a preprint. It has not completed peer review.
Research
High Arsenic Levels Increase Activity Rather Than Diversity or Abundance of Arsenic Metabolism Genes in Paddy Soils
Si-Yu Zhang
East China Normal University
Corresponding Author
ORCiD: https://orcid.org/0000-0001-6701-5790
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
History
CURRENT STATUS: Posted
Version 1
Posted 13 Jan, 2021
No community comments so far
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
Subject Areas
General Microbiology
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Background
Arsenic (As) is a toxic metalloid pervasively present in the environment. Microorganisms have evolved the capacity to metabolize As, and As metabolism genes are ubiquitously present in the environment even in the absence of high concentration of As. However, the As metabolism genes diversity, relative abundance, and transcriptional activity in response to different As levels remain unclear, limiting our understanding of the microbial activities that control the fate of an important environmental pollutant. To address this issue, we applied metagenomics and metatranscriptomics to paddy soils showing a gradient of As concentrations to investigate As resistance genes (ars), including arsR, acr3, arsB, arsC, arsM, arsI, arsP and arsH as well as energy-generating As respiratory oxidation (aioA) and reduction (arrA) genes.
Results
Somewhat unexpectedly, the relative DNA abundances and diversity of ars, aioA and arrA genes were not significantly different between low and high (~10 vs ~100 mg kg-1) As soils. By comparison to available metagenomes from other soils, geographic distance rather than As levels drove the different composition of microbial communities. Arsenic significantly increased ars genes abundance only when its concentration was higher than 410 mg kg -1. In contrast, between low and high (~10 vs ~100 mg kg-1) As soils, metatranscriptomics revealed a significant increase in transcription of ars and aioA genes, which are induced by arsenite, the dominant As species in paddy soils, but not arrA genes, which are induced by arsenate. Co-occurrence patterns of arsR, acr3, and arsM genes were revealed by network analysis corroborating that the arsR, acr3 and arsM genes are usually organized in a single ars operon. The transcriptome level response appeared to be community-wide as opposed to taxon-specific.
Conclusions
High As levels increased the activity of As metabolism genes rather than their abundance or diversity in paddy soils. These findings advance understanding of how microbes respond to high As levels and the diversity of As metabolism genes in paddy soils, and indicated that future studies of As metabolism in soil, and likely other environments, should include the function (transcriptome) level.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7