COMPARATIVE GENOMICS OF ASTAXANTHIN-PRODUCING YEASTS

LUCIA ALVAREZ; DIEGO LIBKIND; NICOLAS BELLORA; MARTIN MOLINE

Bariloche

Congreso; International Specialized Symposium on Yeasts 34 (ISSY34); 2018

The basidiomycetous yeast Phaffia rhodozyma (synonym Xanthophyllomycesdendrorhous) possess a set of unique characteristics of outstanding scientific interestand technological value. P. rhodozyma is the only astaxanthinogenic yeast known, and this carotenoid pigment is considered one of the most potent free reactive oxygens pecies scavenger. P. rhodozyma has additional photoprotective strategies such as the accumulation of mycosporine- glutaminol-glucoside, a UVB-screening compound thatalso has antioxidant properties. Many genetically distinct natural populations of Phaffia spp. are known worldwide, but most of the diversity is found in the Southern Hemisphere, mainly in Australasia, whereas Holarctic populations are mostly genetically uniform. The aim of this work was to evaluate the presence of genes related to photoprotection and antioxidant activities in Phaffia spp. isolates from differentgeographical origins. Eight Phaffia spp. genomes from South America, New Zealand,Japan, Northern Europe, Australia and Tasmania were studied. An alignment-freemethod (Kr) retrieved divergence values of 0.00076 - 0.0081 between Holarctic strains,but 0.089 between Australasia strains and 0.06 - 0.084 between South America and Australasia strains. Genes involved in the synthesis of astanxanthin (idi, CrtE, FPS, crtI,crtYB, crtR, crtS/Ast, Mig1), mycosporine-glutaminol-glucoside (EEVS-like, O-methyl,ATP-grasp) and ROS scavenging enzymes (SOD1 and 2, Catalase 1, 2 and 3) were identified in the genome assemblies by genBlastG. The sixteen genes analyzed were identified in every genome of Phaffia spp. with eval = 0, except for CBS6938 that lacks of MGG genes. The predicted proteins were aligned with Blat to the genome reference CBS7918 and visualized with IGV 2.4.10. Multiple aligments were produced using MUSCLE and protein domains were confirmed with PFAM. Our results indicate that the Phaffia spp. genome is enriched in antioxidant mechanisms and that these mechanisms are conserved through Phaffia spp. from different geographical origins.