Abstract
This paper presents evidence that anthraquinone derivatives can be generally useful for preventing sulfide production from sulfate-reducing bacteria (SRB). We believe there is unique value for these compounds in oilfield and industrial applications where cost-effectiveness and human and environmental safety are of paramount importance.
It has been previously shown that anthraquinones inhibit sulfate respiration, but not aerobic respirations. This aspect permits safe use in wastewater treatment applications where aerobic microbial activity is required. We propose that this specificity is due to the ability of anthraquinones to randomly equilibrate electron flow in the membranes of bacteria of the genus Desulfovibrio. A consequence of this equilibration is that ATP synthesis is uncoupled from respiration. Since sulfate activation has a unique requirement for ATP, sulfate reduction halts with the depletion of ATP level. In this report a positive correlation is shown between inhibition of sulfate respiration by anthraquinones and their reactivity with cytochrome c3, which is a protein considered to be diagnostic of SRB. A model is discussed for involving anthraquinone mediated electron transfer around energy-conserving sites, resulting in a loss of ATP synthesis. This scenario is consistent with the specific inhibition of sulfate respiration in contrast to other respiration processes which do not require ATP.
Inhibition of SRB within a biofilm is dependent upon the species of the anthraquinone and the system hydraulics surrounding the biofilm. Bioavailability of anthraquinone is discussed in terms of soluble and insoluble species of anthraquinone and their mobility within the biofilm. Due to low toxicity, we believe that certain anthraquinones provide an environmentally acceptable alternative to highly toxic biocides for the control of SRB in oilfield water systems.
