The bacteria in environments contaminated with arsenic are affected, surviving those microorganisms that are capable of resisting this environmental pressure and to adapt by means of arsenic-resistance mechanisms: the oxidation and reduction of the metalloid. The aim of the work was to investigate the properties redox in arsenic-tolerant bacteria isolated from natural sediments. The sediments were obtained from Camarones river (I region, Chile). The samples were incubated in mineral media for 7 days, to environment temperature, with agitation. Appropriate dilutions of the samples were sowed in agar R2A and incubated to 25°C, up to 7 days. The tolerance levels for As(III) and As (V) were determined by dilution plate. The property of As- oxidizing or As-reducing of the selected bacteria was investigated using nitrate of silver. The results show the presence of As- resistant bacteria with tolerance levels to >8mM. We found that 36,84% of the bacteria isolated from arsenic-rich sediments presented arsenate reductase activity bigger than 50%. On the other hand, in bacteria isolated from sediments with low concentrations of the metalloid, arseniate reductase activity change among 10% and 25%. This indicated the arsenic selects bacteria witch tolerated high concentrations of arsenic across the transformation of As(V) en As(III).
|Translated title of the contribution||Arsenic transformation by isolated bacteria from sediments enriched with the metalloid|
|Number of pages||5|
|State||Published - 2008|