Studies on the Role of Microorganisms in Mobilization of Selenium in Seleniferous Soils

Abstract

In the present study, sequestration and transformation of bioavailable forms of selenium i.e. selenate and selenite was carried out using aerobic strains isolated from the seleniferous soils of Hoshiarpur-Nawanshahr regions of Punjab in India. Physico-chemical properties of these soil samples presented typical agricultural soils of Punjab. In all ten bacterial strains were selected from thirty bacterial strains on the basis of their unique behaviour towards sequestration and transformation of selenate and selenite. More than 90% sequestration of both selenate and selenite oxyanions was observed in the ten isolates out of 30 strains obtained in the study. SG-26 volatilized significant proportion (approx. 40%) of these oxyanions in pot studies. XRD analysis of sequestered selenate indicated an alternative route of selenium reduction followed by SG-26, for mitigation of selenate form. Polyphasic characterization of these isolates in terms of morphological, physiological, biochemical, antibiotic sensitivity profile and 16S rRNA gene was carried out. Cytoplasmic presence of selenate reductase enzyme was confirmed. No amplification with either primer set used for amplification of selenate reductase gene leads to speculation that a different gene is responsible for selenate reductase in this study.