Acetate threshold concentrations suggest varying energy requirements during anaerobic respiration by Anaeromyxobacter dehalogenans

Abstract

Acetate threshold concentrations were determined under chlororespiring and Fe(III)-reducing conditions for Anaeromyxobacter dehalogenans strain 2CP-C. The acetate threshold concentrations measured were 69 +/- 4, 19 +/- 8, and <1 nM for chlororespiration, amorphous Fe(III) reduction, and Fe(III) citrate reduction, respectively. Residual DeltaG values of -75.4 kJ/mol of electrons for chlororespiration and -41.5 kJ/mol of electrons for amorphous Fe(III) reduction were calculated at the acetate threshold concentration. By comparing threshold concentrations for different metabolisms in a single organism, this study provides insight into the metabolic use of energy under different growth conditions.

FIG. 1.

Depletion curves showing levels of acetate and 2-CP present in cell suspensions of strain 2CP-C during acetate threshold measurements, with two initial acetate concentrations of 20 (A) and 40 μM (B). 2-CP was the electron acceptor, and acetate was the electron donor. The insets show the acetate concentration in the vicinity of the threshold value. Note that the scale of the y axis is in nM measurements in the insets. Data points were averages of triplicate cultures. No acetate depletion was observed in control cultures that did not receive 2-CP.