High prevalence of L. cidri among non-Saccharomyces yeasts in natural environments
To explore the distribution of L. cidri in central and southern Chile, we obtained yeast colonies from tree bark samples collected between 2017 and 2019 that had been previously identified as non-Saccharomyces (Nespolo et al., 2020b) using the internal transcribed spacer region (ITS1-5.8rRNA-ITS2 ). Colonies identified as L. cidri were found in 7 of the 13 sampling regions, between Altos de Lircay National Park (VII Maule Region, Chile) in the north and Coyhaique National Reserve (XI Aysén Region, Chile) in the south. Moreover, the distribution of L. cidri were widely-distributed in South Chile, covering regions from the Pacific coast up to the Andes Mountains (approximately 1,000 km long and 300 km wide) (Fig 1a, Table S4). Overall, we identified 30 L. cidristrains in Patagonia, meaning that L. cidri is the most-represented non-conventional ethanol-tolerant species in our survey. The L. cidri isolation frequency varied between 1.33 to 11.11 % depending on the national park, independent of latitude (Pearson r = -0.338, p -value > 0.05) (Fig S1a, Table S4). In addition, when only non-Saccharomyces yeasts were considered, the isolation frequency values varied between 9.72-100 % (Fig. S1b, Table S4), indicating a high prevalence of this non-conventional yeast in Nothofagus bark samples. The samples from Chile were obtained in four different tree species, N. pumilio (representing 26.7 % of the samples), N. dombeyi (46.7 %), N. antartica (3.3 %), and A. araucana (23.3 %) (Fig. S1c). The frequency of L. cidri in Patagonia was determined by the host tree (hypergeometric test, Table S5); N. dombeyi was the most prevalent host. Additionally, colonies identified as L. cidri were obtained in a previous study from eucalyptus tree sap samples collected in the Central Plateau of Tasmania, Australia (Varela et al., 2020) (Fig. 1a). In this case, L. cidri represented 13% of the total non-Saccharomyces colonies found. Unlike Patagonia, all L. cidri isolates in Australia were obtained from E. gunnii in rich culture media without ethanol. Thus, for further analysis, we randomly selected 25 colonies from different tree sap samples. Altogether, our results demonstrate a high prevalence ofL. cidri in Patagonia and Australia, with a wide distribution from high altitude (Andes Mountains) to low altitude regions (near the Pacific Ocean), covering an extensive range of niches and environmental conditions.