title: Molecular identification of yeasts associated with traditional Egyptian dairy products.
abstract: This study aimed to examine the diversity and ecology of yeasts associated with traditional Egyptian dairy products employing molecular techniques in yeast identification. A total of 120 samples of fresh and stored Domiati cheese, kariesh cheese, and "Matared" cream were collected from local markets and examined. Forty yeast isolates were cultured from these samples and identified using the restriction-fragment length polymorphism (RFLPs) of 5.8S-ITS rDNA region and sequencing of the domains D1 and D2 of the 26S rRNA gene. Yeasts were identified as Issatchenkia orientalis (13 isolates), Candida albicans (4 isolates), Clavispora lusitaniae (Candida lusitaniae) (9 isolates), Kodamaea ohmeri (Pichia ohmeri) (1 isolate), Kluyveromyces marxianus (6 isolates), and Candida catenulata (7 isolates). With the exception of C. lusitaniae, the D1/D2 26S rRNA gene sequences were 100% identical for the yeast isolates within the same species. Phylogenetic reconstruction of C. lusitaniae isolates grouped them into 3 distinguished clusters. Kariesh cheese was found to be the most diverse in its yeast floras and contained the highest total yeast count compared with other examined dairy products. This was linked to the acidic pH and lower salt content of this cheese, which favor the growth and survival of yeasts in foodstuffs. Stored Domiati cheese also contained diverse yeast species involving isolates of the pathogenic yeast C. albicans. This raises the possibility of dairy products being vehicles of transmission of pathogenic yeasts.
authors.affiliation: Food Safety and Microbial Physiology Laboratory, Dairy Dept, Faculty of Agriculture, Mansoura Univ, Mansoura, Egypt. wmel_sharoud@mans.edu.eg
authors.forename: W M
authors.initials: WM
authors.lastname: El-Sharoud
authors.forename: C
authors.initials: C
authors.lastname: Belloch
authors.forename: D
authors.initials: D
authors.lastname: Peris
authors.forename: A
authors.initials: A
authors.lastname: Querol
mesh_terms: D000818:Animals; D002611:Cheese / Q000382:microbiology*; D015169:Colony Count, Microbial; D043302:Cultured Milk Products / Q000382:microbiology*; D004275:DNA, Ribosomal / Q000235:genetics; D004534:Egypt; D005511:Food Handling / Q000379:methods; D005516:Food Microbiology; D005517:Foodborne Diseases / Q000382:microbiology; D006863:Hydrogen-Ion Concentration; D016533:Mycological Typing Techniques; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012335:RNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D017673:Sodium Chloride, Dietary; D014867:Water / Q000032:analysis; D015003:Yeasts / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D004275:DNA, Ribosomal; D012335:RNA, Ribosomal; C065096:RNA, ribosomal, 26S; D017673:Sodium Chloride, Dietary; D014867:Water