Dissimilatory nitrate reduction in Clostridium tertium.

Fermentation balance studies were carried out on Clostridium tertium grown with and without nitrate in the medium. Nitrate reduction increased the efficiency of energy produced from glucose by permitting the utilization of additional sites of substrate level phosphorylation. The effect was even more dramatic in C. tertium than in C. perfringens, with increased cell yields of about 30% being observed in the former compared with 20% in the latter. Unlike C. perfringens, C. tertium responded to the presence of nitrate in the medium with an increased growth rate. A slight increase in the Y ATP of these cultures was also observed, and quantitatively, this appeared to be consistent with the prediction of Stouthammer and Bettenhaussen that Y ATP will vary with the growth rate. Thus, C. tertium, like C. perfringens, was able to use nitrate as an electron acceptor in conjunction with its energy metabolism, suggesting that this may be widespread among the nitrate-reducing anaerobes.