Rhodococcus opacus micro-organism was evaluated as a biocollector for flotation of calcite and magnesite and barite. Analyses of R. opacus cell wall indicated the macromolecules configurationl. The IEP value of R. opacus was around 3.2,. The acidic IEP value of R. opacus could be due to the presence of anionic groups on the wall that dominate over the cationic groups. The adherence test showed the R. opacus affinity for acid-base surfaces.The behavior of the minerals, before and after R. opacus interaction, was evaluated and showed that the cells adhesion shifted both the minerals zeta potential curves and the reversal charges in comparison to their original isoelectric points. Adhesion tests suggested a higher affinity of the bacteria for magnesite than calcite and barite. The experiments of the adsorption rate of the R. opacus on the minerals surfaces showed fast behavior, achieving a maximum of cell adsorption after 5 minutes. Adsorption isotherm curves for the minerals could be categorized as Lagmuir (L) type II. The best bioflotability results for the minerals were achieved for pH 7. Magnesite reached values around 93% for a R. opacus concentration of 100 ppm. For calcite the best flotability was of 55% for a R. opacus concentration of 220 ppm. For barite, the best flotability achieved 70% for a bacterial concentration of 350 ppm. Using the thermodynamic approach of the minerals systems, the adhesion energy of R. opacus on the surfaces was negative. The result suggested a spontaneous adsorption of R. opacus on to the all minerals. For magnesite and calcite, the DLVO theory can predict the cell behavior on the minerals surfaces. The electrostatic attractions determine the interaction forces. For barite and pH 7, the X- DLVO theory predicted the R. opacus adhesion on the surface by acid base interactions.