Selenium volatilization by Rhizospheric Bacteria

Abstract

Selenium in agricultural soils of Punjab has come in public attention lately because of reports from widely divergent backgrounds ranging from research outcome to general awareness campaigns. It was noted that potentially toxic amounts of selenium could be passed on to livestock and human population through fodder and feed resulting in deleterious effects. Although, physico-chemical routes can temporarily provide remediation to seleniferous soils, biological route has been reported to be a potential means to transform selenium to nonbioavailable forms, thus reducing the toxic effects. Among various biotransformation pathways, volatilization through biomethylation has considerable potential for use as a method of remediation. Most importantly, recent observations that phytoremediation of Se by higher plants is closely associated with the potential of rhizosphere bacteria to biotransform Se to volatile/non-volatile alkylselenides, has increased the need to understand the potential of rhizosphere microbes from tropical soils to reduce/volatilize Se. Keeping this in view, the present study was carried out to examine the selenium volatilization potential of bacteria isolated from seleniferous and non-seleniferous agricultural soils. The results of the study present the observations with two soil isolates, Pseudomonas aeruginosa and Bacillus subtilis showing biotransformation Se through reduction vis-à-vis volatilization.