Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 17 4 2025 07 30 660 668 EN Rasoul Mohammadi Department of Medical Parasitology and Mycology, Infectious Diseases and Tropical Medicine Research Center, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran Fatemeh Safari Department of Microbiology, Fal.C., Islamic Azad University, Isfahan, Iran Masoud Sami Department of Food Science and Technology, School of Nutrition and Food Science, Isfahan University of Medical Sciences, Isfahan, Iran Hamidreza Falahati Department of Microbiology, Food and Drug Administration, Isfahan University of Medical Sciences, Isfahan, Iran Ziyaaddin Keshavarzpour Department of Food Science and Technology, School of Nutrition and Food Science, Isfahan University of Medical Sciences, Isfahan, Iran; Department of Nutrition, Faculty of Health & Nutrition, Bushehr University of Medical Sciences, Bushehr, Iran 2024 10 01 2025 06 30 Background and Objectives: Yeasts play a dual role in dairy processing, serving as beneficial fermentative agents that enhance product quality through flavor, texture, and probiotic properties, while also posing spoilage risks if uncontrolled. This study aimed to characterize yeast isolates from industrial and traditional dairy products in Isfahan using PCR-sequencing and phylogenetic analysis. Materials and Methods: A total of 155 dairy samples (fresh/stored, traditional/industrial) were collected. Yeasts were cultured and identified via PCR amplification and sequencing of the ITS1-5.8S rDNA-ITS2 region. Results: Analysis of ITS sequence data identified 28 yeast strains representing eleven species across seven genera, including Saccharomyces cerevisiae (n=8) Kluyveromyces marxianus (n=6), Pichia kudriavzevii (n=4), Candida orthopsilosis (n=2), Pichia membranifaciens (n=2), Pichia cactophila (n=1), Pichia fermentans (n=1), Galactomyces candidum (n=1), Torulaspora delbrueckii (n=1), Debaryomyces hansenii (n=1), and Kluyveromyces lactis (n=1). Phylogenetic analysis grouped isolates into two clusters. Industrial cheese and both industrial/traditional yogurts showed the highest yeast diversity and counts. Notably, C. orthopsilosis was found only in industrial milk and cheese, suggesting potential processing-related contamination. Conclusion: This study highlights the diversity of yeast microbiota in dairy products and underscores the efficacy of ITS sequencing for accurate yeast identification in the dairy industry, aiding quality control and spoilage prevention. https://ijm.tums.ac.ir/index.php/ijm/article/view/5060 https://ijm.tums.ac.ir/index.php/ijm/article/download/5060/1811