P3-19 DNA Barcoding Reveals Considerable Diversity of Fungi in Dairy Products

Wednesday, August 3, 2016
America's Center - St. Louis
Ariel Buehler, Cornell University, Ithaca, NY
Rachel Evanowski, Cornell University, Ithaca, NY
Nicole Martin, Cornell University, Ithaca, NY
Kathryn Boor, Cornell University, Ithaca, NY
Martin Wiedmann, Cornell University, Ithaca, NY
Introduction:  Fungi are major spoilage organisms in dairy products. However, little is known about the diversity of naturally occurring spoilage fungi in raw milk and processed dairy products.

Purpose: Using DNA barcoding data from fungi isolated from raw and finished dairy products, we demonstrate that dairy associated fungal contaminants represent a broad diversity.

Methods: Fungal organisms were isolated from raw and finished dairy products. Samples of raw milk, cheese, and yogurt were plated on Dichloran Rose Bengal Chlortetracycline agar (DRBC) for the selective isolation of fungi. 365 fungal isolates were collected for PCR amplification. Molecular typing of all isolates was performed based on the DNA sequence data of the internal transcribed spacer (ITS) region with primers ITS4 and ITS5. For species identification, ITS region sequences were blast searched against the Unite Database. 

Results: Dairy associated fungal contaminants represent a broad diversity. Twenty-two genera across two phyla were isolated across raw milk, yogurt, and cheese samples. Of the fungal species isolated, 30% were Penicillium, 21% were Debaryomyces, and 11% were Candida. ITS sequencing is a powerful molecular tool for identification and tracking of fungal organisms, providing a far more discriminatory tool than traditional identification methods. 

Significance: This study provides a baseline understanding of the types of fungi and their sources in dairy products through the use of modern molecular subtyping tools.