Abstract: Background and Objective: The Bacillus cereus strain HVR22 bacteria was obtained from isolated budu which produces bacteriocins. The aim of this study was to analyze the effect of crude bacteriocins on pathogen bacteria to observe the effect on cellular morphology of Escherichia coli using electron microscopy and to evaluate its effect on fish fillets. Materials and Methods: A diffusion method was used to measure the width of the clear zone made by Escherichia coli. Antimicrobial solutions of the Bacillus cereus strain HVR22 microbes were used to soak the snapper fillets, bacterial counts were performed on day 0 and 7. Results: Changes in E. coli membrane cell structure were observed under Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) after 48 h. Membranes were exposed to antimicrobial compounds from the Bacillus cereus strain HVR22. Antimicrobials produced by the Bacillus cereus strain HVR22 inhibited E. coli and Salmonella sp., growth on day 0 and 7. Conclusion: The bacteriocin-producing Bacillus cereus strain HVR22 could be used as a natural preservative for fish products.