Multi-locus sequence typing, biogeography and ecology of the astaxanthin-producing yeast Xanthophyllomyces dendrorhous

PALMA, MD; LIBKIND FRATI, D; SAMPAIO JP,

Congreso; Microbiotec09; 2009

The basidiomycetous yeast Xanthophyllomyces dendrorhous (asexual state:Phaffia rhodozyma) has biotechnological relevance due to the production of astaxanthin, a carotenoid pigment used as an additive in aquaculture feeds. This yeast was first isolated in the late 1960’s by Herman Phaff(1) from nutrient-rich exudates of deciduous trees in Japan and Alaska. Subsequently many other strains have been isolated from tree exudates in the Northern Hemisphere and recently a remarkably new Xanthophyllomyces habitat was found in the Southern Hemisphere. In Patagonia (Argentina) X. dendrorhous was consistently isolated from the fruiting bodies of Cyttaria hariotii, an ascomycetous fungus that is a parasite of Nothofagus trees(1). Sequences of the rRNA gene were used in the study of Patagonian and Northern Hemisphere isolates and the ITS-based phylogeny of X. dendrorhous was compared with that of its tree hosts (Betulaceae, Corneaceae, Fagaceae and Nothofagaceae)(1). Although the results suggested a concordance between the two phylogenies and therefore an organization of Xanthophyllomyces populations according to their host type and not to geography, a more detailed analysis should aim at clarifying the global population structure of X. dendrorhous. In the present study we employed multi-locus sequence typing to analyze the genetic structure and biogeography of different lineages of X. dendrorhous. Variable regions of the genes CRTI, CRTS and IDI were sequenced and used for phylogenetic analysis. X. dendrorhous lineages were better resolved than in the previous ITS-based tree. One strain was heterozygous for two of the loci and the haplotypes had to be determined by molecular cloning. In general the CRTI, CRTS and IDI phylogenies were congruent with each other suggesting that clonality dominates the propagation of X. dendrorhous in spite of the fact that this yeast is capable of sexual reproduction(3). Associations with host trees were observed for the isolates from Nothofagus (Patagonia) and Cornus (Japan), which form two clearly distinct populations. However the isolates from Betula (Finland, Russia, Alaska and Japan) and Fagus (Japan) were poorly resolved. We will discuss the present organization of X. dendrorhous in three major clades in which the isolates from Nothofagus form a biogeographic unit whereas the isolates from Cornus and those from Betula + Fagus appear to escape this pattern. This work is supported by an FCT grant (project PTDC/BIA-BDE/73566/2006). 1. Libkind D, Ruffini A, van Broock M, Alves L, Sampaio J. (2007) Biogeography, host specificity, and molecular phylogeny of the basidiomycetous yeast Phaffia rhodozyma and its sexual form, Xanthophyllomyces dendrorhous. Appl Environ Microbiol 73:1120-1125. 2. Weber R, Becerra J, Silva M, Davoli P. (2008) An unsual Xanthophyllomyces strain from leaves of Eucalyptus globulus in Chile. Mycological Research II2: 861-867. 3. Golubev W. (1995) Perfect State of Rhodomyces dendrorhous (Phaffia rhodozyma). Yeast 11: 101-110.