Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 12 5 2020 10 31 431 436 Narges Dadfarma Department of Microbiology, North Tehran Branch, Islamic Azad University, Tehran, Iran Golgis Karimi Cellular and Molecular Biology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran Jamileh Nowroozi Department of Microbiology, North Tehran Branch, Islamic Azad University, Tehran, Iran Naser Nejadi Proteomics Research Center, School of Paramedical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran Bahram Kazemi Cellular and Molecular Biology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran Mojgan Bandehpour Department of Medical Biotechnology, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran 2020 05 24 2020 08 23 Background and Objectives: Lactobacillus casei, an acid-resistant bacterium, has a protective role against the pathogens. So we aimed to determine the proteome of Lactobacillus casei ATCC39392 strain in response to different pHs of 5 and 7 using proteomic analysis. Materials and Methods: Supernatant and bacterial extraction of Lactobacillus casei ATCC39392 adapts at pHs 5 and 7 were isolated using sodium dodecyl sulfate–polyacrylamide gel and two-dimensional gel electrophoresis. The comparison of results showed that 7 protein spots were seen in pH 5 but not in pH 7. Afterward, they were excised and sent for Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) to be identified. Results: Seven different proteins (four secretory and three structural) with different roles in human body health were identified. Prescribed proteins include putative cell wall associated Hydrolase, Glycoside Hydrolase, beta-N-Acetyl hexosaminidase, Histidine Kinase, Chaperonin, metal dependent Hydrolase and Lysozyme. Conclusion: Seven isolated proteins with anti-cancer and digestive impresses are proper subjects in therapy or drug delivery approaches especially oral drug usage for protection against stomach acidic area. https://ijm.tums.ac.ir/index.php/ijm/article/view/2643 https://ijm.tums.ac.ir/index.php/ijm/article/download/2643/1278