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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
chemistry
Diversity and community structure of culturable arsenic-resistant bacteria across a soil arsenic gradient at an abandoned tungsten-tin mining area
Chemosphere, Volume 85, No. 1, Year 2011
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Description
We studied the bacterial diversity at a single location (the Terrubias mine; Salamanca province, Spain) with a gradient of soil As contamination to test if increasing levels of As would (1) change the preponderant groups of arsenic-resistant bacteria and (2) increase the tolerance thresholds to arsenite [As(III)] and arsenate [As(V)] of such bacteria. We studied the genetic and taxonomic diversity of culturable arsenic-resistant bacteria by PCR fingerprinting techniques and 16S rRNA gene sequencing. Then, the tolerance thresholds to As(III) and As(V) were determined for representative strains and mathematically analyzed to determine relationships between tolerances to As(III) and As(V), as well as these tolerances with the soil contamination level. The diversity of the bacterial community was, as expected, inversely related to the soil As content. The overall preponderant arsenic-resistant bacteria were Firmicutes (mainly Bacillus spp.) followed by γ-Proteobacteria (mainly Pseudomonas spp.), with increasing relative frequencies of the former as the soil arsenic concentration increased. Moreover, a strain of the species Rahnella aquatilis (γ-Proteobacteria class) exhibited strong endurance to arsenic, being described for the first time in literature such a phenotype within this bacterial species. Tolerances of the isolates to As(III) and As(V) were correlated but not with their origin (soil contamination level). Most of the strains (64%) showed relatively low tolerances to As(III) and As(V), but the second most numerous group of isolates (19%) showed increased tolerance to As(III) rather than to As(V), even though the As(V) anion is the prevalent arsenic species in soil solution at this location. To our knowledge, this is the first study to report a shift towards preponderance of Gram-positive bacteria (Firmicutes) related to high concentrations of soil arsenic. It was also shown that, under aerobic conditions, strains with relatively enhanced tolerance to As(III) predominated over the most As(V)-tolerant ones. © 2011 Elsevier Ltd.
Authors & Co-Authors
Valverde, Ángel
Spain, Salamanca
Csic - Instituto de Recursos Naturales y Agrobiologia de Salamanca Irnasa
González-Tirante, María
Spain, Salamanca
Csic - Instituto de Recursos Naturales y Agrobiologia de Salamanca Irnasa
Medina-Sierra, Marisol
Colombia, Medellin
Universidad de Antioquia
Santa-Regina, Ignacio
Spain, Salamanca
Csic - Instituto de Recursos Naturales y Agrobiologia de Salamanca Irnasa
García-Sánchez, A.
Spain, Salamanca
Csic - Instituto de Recursos Naturales y Agrobiologia de Salamanca Irnasa
Igual, J. M.
Spain, Salamanca
Csic - Instituto de Recursos Naturales y Agrobiologia de Salamanca Irnasa
Statistics
Citations: 44
Authors: 6
Affiliations: 2
Identifiers
Doi:
10.1016/j.chemosphere.2011.06.025
ISSN:
00456535
Research Areas
Environmental
Genetics And Genomics