Background/aim: The spread of antibiotic-resistant pathogens has resulted in the need for new treatments. The aim of the present study is to investigate the effect of bacteriocin from Lactobacillus acidophilus ATCC 4356 and Lactobacillus plantarum ATCC 8014 on planktonic and biofilm forms of Serratia marcescens strains. Materials and methods: The direct antagonism of the L. plantarum and L. acidophilus cell-free supernatant on S. marcescens cultures was determined using an optical density assay. The bacteriocin was partial purified by ammonium sulfate precipitation. Its molecular weight was analyzed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The effect of bacteriocins on the biofilm of S. marcescens strains was then determined with 2,3,5-triphenyl tetrazolium chloride. Results: The purified bacteriocin from L. plantarum ATCC 8014 and partially purified bacteriocin from L. acidophilus ATCC 4356 displayed noticeable inhibitory activity against planktonic and biofilm forms of S. marcescens strains. SDS-PAGE analysis revealed that the apparent molecular weight of bacteriocin from L. planetarium was 63 kDa, and that of bacteriocin from L. acidophilus was 68 or 48 kDa. Conclusion: The bacteriocins could be effective compounds to control surface-attached pathogenic bacteria and can be used as therapeutic agents after acceptable in vivo experimentation.