Growth Inhibition of Sulfate-Reducing Bacteria in Produced Water from the Petroleum Industry Using Essential Oils

Abstract

Strategies for the control of sulfate-reducing bacteria (SRB) in the oil industry involve the use of high concentrations of biocides, but these may induce bacterial resistance and/or be harmful to public health and the environment. Essential oils (EO) produced by plants inhibit the growth of different microorganisms and are a possible alternative for controlling SRB. We aimed to characterize the bacterial community of produced water obtained from a Brazilian petroleum facility using molecular methods, as well as to evaluate the antimicrobial activity of EO from different plants and their major components against <i>Desulfovibrio alaskensis</i> NCIMB 13491 and against SRB growth directly in the produced water. Denaturing gradient gel electrophoresis revealed the presence of the genera <i>Pelobacter</i> and <i>Marinobacterium</i>, <i>Geotoga petraea</i>, and the SRB <i>Desulfoplanes formicivorans</i> in our produced water samples. Sequencing of <i>dsrA</i> insert-containing clones confirmed the presence of sequences related to <i>D. formicivorans</i>. EO obtained from <i>Citrus aurantifolia</i>, <i>Lippia alba</i> LA44 and <i>Cymbopogon citratus</i>, as well as citral, linalool, eugenol and geraniol, greatly inhibited (minimum inhibitory concentration (MIC) = 78 µg/mL) the growth of <i>D. alaskensis</i> in a liquid medium. The same MIC was obtained directly in the produced water with EO from <i>L. alba</i> LA44 (containing 82% citral) and with pure citral. These findings may help to control detrimental bacteria in the oil industry.