en تخصصي Special Original article Original article <div style="text-align: justify;"><span style="font-family:Times New Roman;"><span style="font-size:14px;"><strong>Background:</strong>&nbsp;The health benefits of probiotic bacteria are not unknown to anyone. On the other hand, indigenous dairy sources are a potential source of native probiotics. This study aimed to describe the inhibitory activity of Cell-Free Supernatant (CFS), planktonic cells, and biofilm form of <em>Lactobacillus</em> strains isolated from native dairy sources on food pathogens.<br> <strong>Methods:</strong> Antibacterial activities of the CFS of <em>lactobacillus</em> strains were assessed by the microplate method and via violet staining, and in planktonic cells, and biofilm forms were performed by the spread plate method.<br> <strong>Results:</strong> The results showed that despite the large differences in biofilm formation power among the strains, most of them can produce biofilm. <em>Lactobacillus delbrueckii </em>subsp<em>. bulgaricus</em>, <em>Lactobacillus plantarum, Lactobacillus delbrueckii</em> subsp. <em>Lactis</em>, <em>Lactobacillus brevis</em>, and <em>Lactobacillus lactis</em> subsp. <em>lactis</em> formed the strongest biofilm, respectively. Planktonic states reduce the pathogens bacterial by about 1.43 log, but in biofilm forms, decreased <em>Listeria monocytogenes</em> by about 4.8 log compared to the control, and in the case of <em>Pseudomonas aeruginosa</em>, a growth reduction of about 2.8 logs was observed.<br> <strong>Conclusion:</strong> According to the study, biofilm produced by probiotic strains can be considered a new approach for biological control. Also, indigenous dairy sources can be considered by researchers to extract natural and beneficial probiotics.<br> <br> <strong>DOI:&nbsp;</strong>10.18502/jfqhc.8.4.8257&nbsp;</span></span></div> Biofilms, Lactobacillales, Lactobacillus, Probiotics, Anti-Infective Agents, Dairy Products 162 168 http://jfqhc.ssu.ac.ir/browse.php?a_code=A-10-1082-1&slc_lang=en&sid=1 Z. Rezaei 0000-0002-8793-8290 No Department of Food Hygiene and Aquaculture, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran A. Salari No Department of Food Hygiene and Aquaculture, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran S. Khanzadi Khanzadi@um.ac.ir 0000-0003-0106-587X Yes Department of Food Hygiene and Aquaculture, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran