فائزه اجرلو

The carotenoid-producing yeasts have a widespread distribiution  worldwide. However, isolation of carotenoid-producing yeasts with valuable astaxanthin have been only reported from limited areas and specific habitats. The aim of this study was to apply the multiple polymerase chain reaction method for faster molecular screening of isolates for the yeasts in the exudation sap from birch trees (Betula pendula Roth.) in Alborz Province of Iran with astaxanthin production capacity and toevaluate its efficiency.

This cross-sectional study was carried out by sampling in May 2018 from one of the natural habitats of birch trees Batula Pendula in Alborz Province, Iran. After isolation of yeasts using selected media and purification of yeast colonies with various pink to red colors, yeasts genomic nucleic acids were extracted and molecular screening for astaxanthin-producing detection of isolates was performed by multiple polymerase chain reaction (Multiplex-PCR).

Out of 42 pigmented colonies during sampling and isolation in one cross-sectional study, 23 pink to red colonies were evaluated by Multiplex-PCR method. Of these isolates, three were positive and the rest were negative. The results were validated by determining the ribosomal gene sequencing.

The present study demonstrates the specificity of the multiple polymerase chain     reaction method in fast and cost-effective molecular screening of astaxanthin-producing yeast   isolates and the applicability of this method to study other natural habitats of these yeasts.

Background & A portion of biodiversity and variability of life on earth belongs to the yeasts. The caroptenoid-producing yeasts are economically important and their distinct natural habitats are of interest. In this study, isolation and molecular identification of carotenoid-producing yeasts of the exudates of endangered birch trees (Betula pendula Roth.) at Marmisho in Northwest Iran were performed. Materials & This cross-sectional study carried out by sampling from exudates of birch trees (Betula pendula Roth.) at a natural habitat located in West Azerbaijan Province in the Northwest of Iran. Using selective media, the isolation of the yeasts was done. The screening was initially based on the color and shape of the colonies during one-month incubation along with simple rapid tests to check the existence of carotenoid pigments. Finally, the D1/D2 region rDNA sequencing was accomplished for 19 isolates. 19 out of 45 isolates with pink-red colonies were selected for ribosomal gene sequencing. Phylogenetic results showed that the carotenoid-producing yeasts are in the Basidiomycota division including Rhodotorula, Cystofilobasidium, Cystobasidium, Rhodosporidiobolus, Ustilentyloma, and Xanthophyllomyces.  The unique pattern of carotenogenic yeasts community at this ecological niche and placing in 6 genera with the capability to produce a variety of carotenoid structures indicate that the exudates of birch trees (Betula pendula Roth.) include a wide diversity for native carotenoid-producing yeasts. This study is the first report presenting the diversity of carotenoid-producing yeasts in the Northwest of Iran with a distinct consortium of native yeasts at this habitat.