Biological transformations of selenium by microorganisms
Lieke Riadi1* and John P. Barford2
1Department of Chemical Engineering, The University of Surabaya, Surabaya 60292, Indonesia,
2Department of Chemical Engineering, The University of Sydney, NSW 2006, Australia
Current Address: Department of Chemical Engineering, The Hongkong University of Science and
Technology, Clear Water Bay, Kowloon, Hongkong.
(Received 10 September 1998 / Accepted 9 November 1998)
Abstract.
Microorganisms can enzymatically reduce a variety of metals in metabolic processes. Selenate [Se (VI)] and selenite [Se(IV)] which are known toxicants serve as terminal electron acceptors to support the growth of some microorganisms. Reduction of Se(VI) or Se(IV) to Se(O) is an important mechanism far the precipitation of selenium from contaminated waters. In addition, biomethylation of Se (VI) or Se IV is also known as one of the detoxification processes of these selenium oxyanions. A problem still remains in the characterisation of the carbon metabolism in selenium oxidising reducing bacteria. Some researchers have investigated the utilisation of some carbon compounds for selenium reducing bacteria. However, a detailed study of carbon metabolism has not been reported. Furthermore, the effect of other ions (except nitrate) as competitive electron acceptor for selenium oxyanions has not been studied in detail. Therefore, it is of interest to fill the existing gap in this research area. In this paper, we review the biological transformation of selenium by microorganisms and describe initial experiments in our laboratories on the carbon metabolism of a selenium reducing microorganism and the effect of nitrate on electron acceptance by selenium oxyanions.
Keywords: Biological transformation, selenium, microorganism
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