| Title | Microbial transformation of Se oxyanions in cultures of Delftia lacustris grown under aerobic conditions |
|---|---|
| Author | Shrutika L. Wadgaonkar1*, Yarlagadda V. Nancharaiah2,3, Claus Jacob4, Giovanni Esposito5, and Piet N. L. Lens1,6 |
| Address | 1UNESCO IHE Institute for water Education, Delft DA 2601, The Netherlands, 2Biofouling and Biofilm Processes Section of Water and Steam Chemistry Division, Bhabha Atomic Research Centre, 603 102, Tamil Nadu, India, 3Homi Bhabha National Institute, Anushakti Nagar Complex, Mumbai 400 094, India, 4Division of Bioorganic Chemistry, School of Pharmacy, Saarland University, Campus B2, Saarland, Germany, 5Department of Civil, Architectural and Environmental Engineering, University of Napoli "Federico II", 80125 Napoli, Italy, 6National University of Ireland Galway, Galway, H91 TK33, Ireland |
| Bibliography | Journal of Microbiology, 57(5),362–371, 2019, |
| DOI | 10.1007/s12275-019-8427-x |
| Key Words | bioremediation, Delftia lacustris, aerobic selenate reduction, organo-selenium compounds, selenium speciation |
| Abstract | Delftia lacustris is reported for the first time as a selenate and selenite reducing bacterium, capable of tolerating and growing in the presence of ≥ 100 mM selenate and 25 mM selenite. The selenate reduction profiles of D. lacustris were investigated by varying selenate concentration, inoculum size, concentration and source of organic electron donor in minimal salt medium. Interestingly, the bacterium was able to reduce both selenate and selenite under aerobic conditions. Although considerable removal of selenate was observed at all concentrations investigated, D. lacustris was able to completely reduce 0.1 mM selenate within 96 h using lactate as the carbon source. Around 62.2% unaccounted selenium (unidentified organo-selenium compounds), 10.9% elemental selenium and 26.9% selenite were determined in the medium after complete reduction of selenate. Studies of the enzymatic activity of the cell fractions show that the selenite/selenate reducing enzymes were intracellular and independent of NADPH availability. D. lacustris shows an unique metabolism of selenium oxyanions to form elemental selenium and possibly also selenium ester compounds, thus a potential candidate for the remediation of selenium-contaminated wastewaters in aerobic environments. This novel finding will advance the field of bioremediation of selenium-contaminated sites and selenium bio-recovery and the production of potentially beneficial organic and inorganic reactive selenium species. |