Molecular Investigation of Diversity Normal Yeast Flora in Cow Raw Milk Industrial Farms of Tehran Province and Alborz

Abstract

Background and Objective: Milk is a completely rich and complex environment suitable for different microorganisms including bacteria and Fungi. The majority of studies were conducted on milk-bacterial flora and aflatoxin-contaminations in dairy products; however, despite the importance of yeasts in usage as starter in the dairy industries and their effect on the taste of dairy products as well as in dairy probiotic characteristics, almost no information exist concerning fungal-flora in milk. So, the aim of this study was investigation on the raw milk yeast-microflora and it’s relation to the hygienic level and other characteristics of dairy farms. Existence of fungus were studied in defined raw milk samples and the diversity of isolated yeasts were examined. Materials and Methods: Samples were collected within a period of one year (March 2016-March 2017) and evaluated based on Internal Transcribed Spacer (ITS-1-ITS-2) parts of rDNA. Isolated yeasts were identified using PCR-RFLP and Sequencing tests. Results: Total of 262 raw milk samples were collected from 14 farms in Tehran and Alborz provinces in Iran. About 66% of milk samples contained yeast microflora. The dominant isolated yeasts were characterized as: Candida globose, Geotrichum candidum, Pichia kudriavzevii, Tricosporon asahii, Pichia jadinii, Kluyveromyces marxianus, Magnusiomyces capitatus, Wickeihameilla pararugosa, and Candida inconspicua. Other candida species such as Candida parapsilosis, Candida tropicalis, and Candida glabrata were also isolated in a limited level. Conclusion: Dominant yeast flora was identified in raw cow’s milk samples. The obtained results also indicated that fungal diversity varies from field to field. However, similarities in some isolated species have been revealed.

Keywords

• milk
• micro-flora
• pcr-rflp
• sequencing
• yeast