The accumulation of water and sludge in oil storage tanks leads to microbial contamination. The study of these microbial communities is of particular interest, especially the sulfate reducing microorganisms (SRM) which are mainly responsible for microbiologically influenced corrosion (MIC). Usually, the development of those microorganisms is controlled by the addition of biocides. The objective of this work was to evaluate the effect of a biocide (THPS) on these communities in a batch fractionated assay.