Changing the wettability of reservoir rock towards strongly water-wet state is effective way to enhance oil recovery from fractured carbonate reservoirs which are typically oil-wet. Regarding this fact, the injection of surfactant and the bacterial solution as EOR agents is proposed in the current work as a potential method to alter the wettability of rock surface reservoir. Nevertheless, there is a definite lack of experimental data regarding this method and the synergistic effect of both chemical and bacterial solutions on this process. In this study, the sole and combined effects of the bacterial solution using an Enterobacter cloacae strain as a biosurfactant-producer are compared with sodium dodecylbenzenesulfonate (SDBS) and dodecyltrimethylammonium bromide (C12TAB) as anionic and cationic surfactants, respectively. For this purpose, static contact angle measurement are utilized to investigate the wettability alteration. The obtained results revealed that bacterial solution can alter the wettability of calcite surfaces to the same extent of C12TAB and more than SDBS. In addition, base on the obtained results it can be concluded that the combination of bacterial solution and chemical surfactant are not proposed for in-situ biosurfactant techniques, since the Enterobacter cloacae uses the chemical surfactant as the carbon source concomitantly a reduction in the biosurfactant production occurs.