INHIBITION OF SULFATE RESPIRATION BY 1,8-DIHYDROXYANTHRAQUINONE AND OTHER ANTHRAQUINONE DERIVATIVES

Derivatives of 9,10-anthracenedione, or anthraquinone, were shown to i nhibit respiratory sulfate reduction by pure cultures of sulfate-reduc ing bacteria, as well as by crude enrichment cultures. Structure-activ ity studies showed that an increasing degree of substitution of the an thraquinone nucleus resulted in increasing 50% inhibition (I-50) value s for sulfate respiration. Addition of charged ring substituents also resulted in an increase in the I-50 concentration. Experiments carried out with 1,8-dihydroxyanthraquinone demonstrated inhibition of hydrog en-dependent sulfate respiration but not hydrogen-dependent sulfite or thiosulfate respiration. Addition of pyruvate resulted in stimulation of sulfate-dependent hydrogen oxidation in the presence of the anthra quinone. These observations, together with a direct demonstration of u ncoupling in French press vesicle preparations, suggest that the under lying mechanism of inhibition is uncoupling of ATP synthesis from elec tron transfer reactions. The low I-50 values for inhibition (0.5 to 10 mu M) and the relatively low general toxicity of anthraquinones sugge st that these compounds may be useful for inhibition of sulfide genera tion in situations which are incompatible with the use of broadly toxi c biocides.