Arsenic Detoxification by Geobacter Species

Insight into the mechanisms for arsenic detoxification byGeobacterspecies is expected to improve the understanding of global cycling of arsenic in iron-rich subsurface sedimentary environments. Analysis of 14 differentGeobactergenomes showed that all of these species have genes coding for an arsenic...

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Bibliographic Details
Published in:Applied and environmental microbiology 2016-12, Vol.83 (4)
Main Authors: Dang, Yan, Walker, David J. F., Vautour, Kaitlin E., Dixon, Steven, Holmes, Dawn E.
Format: Article
Language:English
Subjects:
ars operon
arsenic
BASIC BIOLOGICAL SCIENCES
detoxification
genetics
Geobacter
iron reduction
MATERIALS SCIENCE
transcriptomics
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Summary:Insight into the mechanisms for arsenic detoxification byGeobacterspecies is expected to improve the understanding of global cycling of arsenic in iron-rich subsurface sedimentary environments. Analysis of 14 differentGeobactergenomes showed that all of these species have genes coding for an arsenic detoxification system (arsoperon), and several have genes required for arsenic respiration (arroperon) and methylation (arsM). Genes encoding four arsenic repressor-like proteins were detected in the genome ofG. sulfurreducens; however, only one (ArsR1) regulated transcription of thearsoperon. Elimination ofarsR1from theG. sulfurreducenschromosome resulted in enhanced transcription of genes coding for the arsenic efflux pump (Acr3) and arsenate reductase (ArsC). When the gene coding for Acr3 was deleted, cells were not able to grow in the presence of either the oxidized or reduced form of arsenic, whilearsCdeletion mutants could grow in the presence of arsenite but not arsenate. These studies shed light on howGeobacterinfluences arsenic mobility in anoxic sediments and may help us develop methods to remediate arsenic contamination in the subsurface. This study examines arsenic transformation mechanisms utilized byGeobacter, a genus of iron-reducing bacteria that are predominant in many anoxic iron-rich subsurface environments.Geobacterspecies play a major role in microbially mediated arsenic release from metal hydroxides in the subsurface. This release raises arsenic concentrations in drinking water to levels that are high enough to cause major health problems. Therefore, information obtained from studies ofGeobactershould shed light on arsenic cycling in iron-rich subsurface sedimentary environments, which may help reduce arsenic-associated illnesses. These studies should also help in the development of biosensors that can be used to detect arsenic contaminants in anoxic subsurface environments. We examined 14 differentGeobacterge
ISSN:0099-2240
1098-5336