The aim of this research was to investigate the bacteriocins produced by Bacillus strains isolated from the spring water of Rize, in Turkey. Bacillus cereus RS108 was identified by both conventional and molecular methods, bacteriocin RS108 which was produced by RS108, was partially characterized. A broad range of indicator strains, including several species of bacteria and yeast like fungi, was inhibited by a crude bacteriocin obtained from culture supernatant fluid. The best antimicrobial activity of RS108 was detected on S. pyogenes, L. monocitogenes, and another B. cereus strains, and at the late exponential growth phase. RS108 was stable at 90 degrees C, but the activity was lost when the temperature reached 100 degrees C. It was inactivated by proteinase K. It was resistant 10% ration of some solvent (chloroform, ethanol etc.), but sensitive high concentration. Bacteriocin activity was observed in the pH range of 3.0-9.0. SDS-PAGE analysis of the partially purified bacteriocin shows that the molecular weight of bacteriocin RS108 is approximately 4 kDa.