U.S. Geological Survey Toxic Substances Hydrology Program--Proceedings of the Technical Meeting, Colorado Springs, Colorado, September 20-24, 1993, Water-Resources Investigations Report 94-4015

Anaerobic Growth of Bacterial Strain Ses3 with Selenate as the Electron Acceptor

Abstract

The bacterial strain SES3 is capable of growth with selenate, nitrate, or Fe(III) as electron acceptors, and lactate as an electron donor. Selenate is reduced through selenite to elemental selenium, whereas nitrate was reduced through nitrite to ammonia, and Fe(III) was reduced to Fe(II). Lactate was oxidized to CO₂ and acetate in an approximately 1:1 ratio. Results of washed-cell experiments comparing nitrate and selenate reduction in either nitrate-grown or selenate-grown cells indicated that separate enzyme systems performed the reductions. Washcloth experiments using uniformly labelled, [U-^l4C] lactate, showed that fumarate, arsenate, and O₂ also functioned as electron acceptors. The respiratory inhibitors azide, carbonyl cyanide m-chlorophenyl-hydrazone (CCCP), and dinitrophenol (DNP) inhibited both selenate and nitrate reduction in washed-cell suspensions.