Selenite bioreduction by a consortium of halophilic/halotolerant bacteria and/or yeasts in saline media

Abstract

Selenium oxyanions are released into environments by natural and anthropogenic activities and are present in agricultural and glass manufacturing wastewater in several locations worldwide. Excessive amounts of this metalloid have adverse effects on the health of living organisms. Halophilic and halotolerant microorganisms were selected for selenium oxyanions remediation due to presence of significant amount of salt in selenium-containing wastewater. Effects of aeration, carbon sources, competitive electron acceptors, and reductase inhibitors were investigated on SeO32− bio-removal. Additionally, NO3−-containing wastewater were exploited to investigate SeO32− remediation in synthetic agricultural effluents. The results showed that the SeO32− removal extent is maximum in aerobic conditions with succinate as a carbon source. SO42− and PO43− do not significantly interfere with SeO32− reduction, while WO42− and TeO32− decrease the SeO32− removal percentage (up to 35 and 37%, respectively). Furthermore, NO3− had an adverse effect on SeO32− biotransformation by our consortia. All consortia reduced SeO32− in synthetic agricultural wastewaters with a 45–53% removal within 120 h. This study suggests that consortia of halophilic/halotolerant bacteria and yeasts could be applied to treat SeO32--contaminated drainage water. In addition, sulphates, and phosphates do not interfere with selenite bioreduction by these consortia, which makes them suitable candidates for the bioremediation of selenium-containing wastewater.