Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 16 6 2024 12 08 763 772 EN Anis Syahirah Saifor Adzuan Microbial Metabolite Laboratory, Atta-ur-Rahman Institute for Natural Products Discovery (AuRIns), Universiti Teknologi MARA (UiTM), Puncak Alam, Selangor, Malaysia; School of Biology, Faculty of Applied Sciences, Universiti Teknologi MARA (UiTM), Shah Alam, Selangor, Malaysia Sharifah Aminah Syed Mohamad Microbial Metabolite Laboratory, Atta-ur-Rahman Institute for Natural Products Discovery (AuRIns), Universiti Teknologi MARA (UiTM), Puncak Alam, Selangor, Malaysia; School of Biology, Faculty of Applied Sciences, Universiti Teknologi MARA (UiTM), Shah Alam, Selangor, Malaysia Rashidah Iberahim School of Biology, Faculty of Applied Sciences, Universiti Teknologi MARA (UiTM), Kuala Pilah, Negeri Sembilan, Malaysia Noor Nadia Syahira Mohd Kamal School of Biology, Faculty of Applied Sciences, Universiti Teknologi MARA (UiTM), Shah Alam, Selangor, Malaysia Nurliana Abd Mutalib Microbial Metabolite Laboratory, Atta-ur-Rahman Institute for Natural Products Discovery (AuRIns), Universiti Teknologi MARA (UiTM), Puncak Alam, Selangor, Malaysia Nur Intan Hasbullah Microbial Metabolite Laboratory, Atta-ur-Rahman Institute for Natural Products Discovery (AuRIns), Universiti Teknologi MARA (UiTM), Puncak Alam, Selangor, Malaysia; School of Biology, Faculty of Applied Sciences, Universiti Teknologi MARA (UiTM), Kuala Pilah, Negeri Sembilan, Malaysia Muneer Alsaydi Microbial Metabolite Laboratory, Atta-ur-Rahman Institute for Natural Products Discovery (AuRIns), Universiti Teknologi MARA (UiTM), Puncak Alam, Selangor, Malaysia; Department of Food Science and Technology, Faculty of Agriculture, Ibb University, Ibb, Yemen Nor'aishah Hasan School of Biology, Faculty of Applied Sciences, Universiti Teknologi MARA (UiTM), Kuala Pilah, Negeri Sembilan, Malaysia Low Kheng Oon Cell and Synthetic Biology Centre, Malaysia Genome and Vaccine Institute (MGVI), National Institutes of Biotechnology Malaysia (NIBM), Kajang, Selangor, Malaysia Olaide Olawunmi Ajibola Faculty of Resource Science and Technology, Universiti Malaysia Sarawak (UNIMAS), Kota Samarahan, Sarawak, Malaysia Rozila Alias Centre for Foundation and General Studies, Universiti Selangor, Shah Alam, Selangor, Malaysia Maimunah Mustakim Centre for Medical Laboratory Technology Studies, Faculty of Health Sciences, Universiti Teknologi MARA (UiTM), Puncak Alam, Selangor, Malaysia Azlin Sham Rambely Centre for Medical Laboratory Technology Studies, Faculty of Health Sciences, Universiti Teknologi MARA (UiTM), Puncak Alam, Selangor, Malaysia Emida Mohamed Centre for Medical Laboratory Technology Studies, Faculty of Health Sciences, Universiti Teknologi MARA (UiTM), Puncak Alam, Selangor, Malaysia Mohammad Reza Pourmand Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran 2024 04 22 2024 07 30 Background and Objectives: The most common cause of severe foodborne salmonellosis is S. Typhimurium. Its interaction with intestinal epithelial cells is little known. Lactic acid bacteria (LAB) were recognized as a prominent probiotic gastrointestinal microbiota of humans and animals that confer health-promoting and protective effects. This study aims to determine the anti-invasion and antibacterial effects of heat-killed LAB (HK-LAB) isolates against S. Typhimurium towards human intestinal cells. Materials and Methods: 12 HK-LAB isolates from 3 sources of origin (stingless bee, plant, and food) were tested to determine the adhesion of HK-LAB to Caco-2 cells, anti-invasion and antibacterial activities against S. Typhimurium, the adhesion and invasion pattern of S. Typhimurium on intestinal epithelial cells (Caco-2) and assessing the effect of LAB on the S. Typhimurium-host cell interaction. Results: Tairu isolates from food have the highest adhesion rate with 19 ± 1.32/10 Caco-2 cells followed by HK-LAB R-isolate from plant 17 ± 0.70/10 Caco-2 cells, which is similar to the control (Lactobacillus casei). In the anti-invasion assay, the two HK-LAB isolates that had the strongest adherence to Caco-2 cells, Tairu-isolate inhibited at 78.1 ± 3.06% and R-isolate inhibited at 64.76 ± 9.02% compared to the positive control (63.81 ± 1.15%), which led to increased suppression of S. Typhimurium accordingly. Tairu and R isolates were tested for their antibacterial ability against S. Typhimurium. Both R and Tairu isolates displayed strong inhibition zones (27 ± 0.06 mm, 23 ± 0.06 mm) respectively. Conclusion: These findings suggest that the anti-invasion activities of HK-LAB R and Tairu may correlate to their bactericidal effects that serve to protect the host from infection. https://ijm.tums.ac.ir/index.php/ijm/article/view/4746 https://ijm.tums.ac.ir/index.php/ijm/article/download/4746/1727