Cell yield (YM) of Thauera selenatis grown anaerobically with acetate plus selenate or nitrate

Thauera selenatis was grown anaerobically in minimal medium with either selenate or nitrate as the terminal electron acceptor and acetate as the carbon source and electron donor. The molar cell protein yields, YM-protein (selenate) and YM-protein (nitrate), were found to be 7.8 g cell protein/mol selenite formed and 7.5 g cell protein/mol nitrite formed, respectively. These values represent YM values of 57 and 55 g (dry weight)/mol acetate when selenate or nitrate was the electron acceptor, respectively. Based upon a calculated YATP value of 10.0 g (dry weight) cells/mol ATP, for growth on acetate in inorganic salts, growth with selenate as the terminal electron acceptor theoretically yielded 5.7 ATP/acetate oxidized, and 5.5 ATP when nitrate was the terminal electron acceptor. The results support the conclusion that energy is conserved via electron transport phosphorylation when selenate or nitrate reduction are the terminal electron acceptors during anaerobic growth with acetate.