[Redox Transformation of Arsenic and Antimony in Soils Mediated by Pantoea sp. IMH]

Soil contamination with co-existing arsenic (As) and antimony (Sb) has become a serious environmental problem worldwide. Microorganisms play a dominant role in the redox transformation and mobilization of As and Sb. As and Sb belong to the same family; they are alike in nature and have related microbial oxidation-reduction mechanisms. However, limited knowledge is available about the impact of As-reducing bacteria on the fate of As and Sb in their co-existing soils. The purpose of this study was to explore the redox transformation and release of As and Sb in the presence of an arsC carrier, Pantoea sp. IMH, which has high As(Ⅴ)-reducing capability. In addition to the IMH incubation system, the dead cell system and abiotic control experiments were conducted. The results showed that the IMH incubation reduced all soluble As(Ⅴ) (72.7 μg·L^-1) to As(Ⅲ) form, whereas soluble Sb(Ⅴ) (364.8 μg·L^-1) was not reduced, indicating that the As (V)-reducing pathway mediated by arsC genesis was not able to reduce Sb(Ⅴ). The amounts of total As (506.8 μg·L^-1) and total Sb (821.1 μg·L^-1) in the dead cell system were approximately four times higher than in the living cell system (As=155.2 μg·L^-1; Sb=364.8 μg·L^-1) and the abiotic control (As=57.6 μg·L^-1; Sb=271.1 μg·L^-1) because of the biomolecules released from the dead cells which enhanced the release of As and Sb. The correlation analysis of dissolved As and Sb showed that the release of total As and Sb was correlated (P<0.05) in three systems. Our study shed new light on the impact of bacteria on the fate of As and Sb in soils.