CO metabolism ofDesulfovibrio vulgarisstrain Madison: physiological function in the absence or presence of exogeneous substrates

Trace amounts of carbon monoxide were produced and subsequently consumed during the growth of Desulfovibrio vulgaris on organic electron donors. D. vulgaris also utilized carbon monoxide as the sole electron donor for growth and sulfate reduction. Growth of D. vulgaris on CO, H2 or organic electron donors was inhibited at ≥4.5% CO in the culture headspace. At lower CO concentrations, hydrogen was produced as a consequence of CO consumption and consumed when the CO partial pressure was decreased. The rate of CO consumption was ten-fold higher in D. vulgaris grown on either CO, lactate or pyruvate than when cells were grown on H2 as electron donor. The physiological function of CO metabolism and a CO-dependent hydrogen cycle in D. vulgaris is discussed.