Yeast diversity in extreme environments of southern South America

DE GARCIA V., MOLINÉ M., LIBKIND D.

Perugia

Simposio; 32nd International Specialized symposium on Yeasts; 2015

Session 1A: Yeasts in the environment: ecology and taxonomy Yeast diversity in extreme environments of southern South America Virginia de García, Martín Moliné, Diego Libkind Laboratorio de Microbiología Aplicada y Biotecnología, INIBIOMA, UNComahue ? CONICET, Bariloche, Argentina.email@email.com: libkindfd@comahue-conicet.gob.ar Yeasts that constantly live under stress conditions evolve adaptive mechanisms destinated to minimize or resist their negative effects and thus still permit survival and reproduction. The study of yeasts inhabiting extreme environments is still limited, particularly in pristine habitats of South America. Here we resume numerous yeast diversity studies performed in non-conventional environments, mainly of Argentina, which are exposed to one or more of the following factors: high UV irradiance, desiccation, low temperatures, very high (> 10) or low pH (< 2), presence of heavy metals (volcanic origin), ultraoligotrophicity. Over 750 yeasts and dimorphic fungi were collected, molecularly identified, and when possible relevant secondary metabolites were screened, as well as ability to tolerate several types of stress in lab conditions. The latter include carotenoid pigments, mycosporines (UV sunscreens), psycroactive enzymes, among others. In some cases these activities could be correlated to habitat characteristics and for such (ex. mycosporines, carotenoid pigments, heavy metal tolerance) their potential role in the adaptive mechanisms to specific stress factors was evaluated. At least 100 different yeast species were identified and no less than 25 novel taxa were detected. Genome sequencing and analysis was performed for biotechnologically relevant isolates of Phaffia rhodozyma, Saccharomyces eubayanus, S. uvarum, Giraudozyma gen. nov., Guehomyces pullulans. The present work represents an overview of our findings related to the biodiversity, ecology and physiology of extremophilic and polyextromophilic yeasts in southern South America. KEYWORDS: extremophilic yeasts, UV radiation, Cold habitats, adaptation