Impact of glucose on microbial community of a soil containing pyrite cinders: Role of bacteria in arsenic mobilization under submerged condition

• Published in: Soil biology & biochemistry Vol. 42; no. 5; pp. 699 - 707
• Main Authors: Corsini, Anna, Cavalca, Lucia, Crippa, Laura, Zaccheo, Patrizia, Andreoni, Vincenza
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 01-05-2010; Elsevier
• Subjects: Agronomy. Soil science and plant productions; Ars genes; arsenates; arsenic; arsenites; As solubilization; As(III); As(V); As-resistant bacteria; Bacillus; Bacterial redox activity; Biochemistry and biology; Biological and medical sciences; Chemical, physicochemical, biochemical and biological properties; desorption; dissolution; Flavobacterium; flooded conditions; Fundamental and applied biological sciences. Psychology; genes; glucose; ion transport; iron; manganese; microbial activity; microbial genetics; Micromonospora; Paenibacillus; Physics, chemistry, biochemistry and biology of agricultural and forest soils; polluted soils; Pyrite cinders; pyrites; redox potential; Rhodococcus; ribosomal RNA; soil microorganisms; Soil science; soil solution; solubilization; species diversity; Staphylococcus; transport proteins; As(V); As solubilization; Ars genes; As-resistant bacteria; Bacterial redox activity; Pyrite cinders; As(III); Oxidation reduction; Submersion; Glucose; Solubilization; Arsenic V; Soils; Pyrite; Gene; Arsenic III; Bacteria; Soil science; Microbial community
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/j.soilbio.2009.12.010

Arsenic transformation and mobilization in a pyrite cinder-polluted soil were studied under submerged conditions both in the presence and absence of glucose. The presence of the carbon source enhanced bacterial activity and a reduction in the redox potential, resulting in release of higher amounts of arsenic iron and manganese in the aqueous phase. Since arsenic solubilization was not concomitant to that of iron, desorption rather than dissolution was found to be the main mechanism controlling its release from pyrite cinders. Arsenate was reduced to arsenite whose presence increased during the time course of the experiment. Denaturing gradient gel electrophoresis analysis of 16S rRNA genes of the total bacterial community revealed that the addition of glucose stimulated uncultivable populations of
Flavobacterium and
Paenibacillus. The isolation technique enabled the characterisation of nineteen arsenic-resistant bacteria, mostly related to the facultative aerobic genera
Bacillus, Paenibacillus, Staphylococcus and to
Rhodococcus and
Micromonospora. Most of them contained putative arsenate reductase and/or arsenite efflux pump as indicated by the presence of
ArsC and/or
ArsB genes. Four strains showed the ability to reduce arsenate by an intracellular detoxification mechanism, and one strain was able to oxidize arsenite, indicating that bacteria with the ability to oxidize or reduce arsenic are ubiquitous in soils. The findings confirm that bacterial activity was responsible for the arsenic reduction causing the solubilization of the metalloid from pyrite cinders to aqueous phases. Reducing conditions, such as those present in flooded soils in the presence of readily utilizable carbon sources could induce arsenic mobilization.