3.1 Isolation of ethanol-tolerant yeast species from Atacama
Desert flora
To identify ethanol-tolerant yeast strains from the Atacama Desert, we
collected 22 samples from various tissues of native trees, including
bark, bark-exuded gum, pods, and flowers. The tree species sampled
included Neltuma chilensis (Algarrobo), Geoffroea
decorticans (Chañar) and Strombocarpa tamarugo (Tamarugo). After
subjecting these samples to culture enrichment in rich media containing
4% ethanol, a total of 91 ethanol-tolerant yeast colonies were obtained
(Table S1 ). Among these colonies, 60 were isolated fromN. chilensis , 10 from S. tamarugo , and 21 from G.
decorticans .
Next, we amplified the ITS region and sequenced at least one colony per
sample according to the size of the ITS region obtained. Based on these
sequencing results, we identified 36 isolates as belonging to the
basidiomycetous phylum, specifically the genera Kwoniella ,Rhodotorula, and Naganishia. Additionally, we identified
55 isolates corresponding to ascomycetous species, belonging to the
genera Zalaria, Starmerella , and Nakazawaea .
To identify fermenting yeast, we conducted the Durham tube fermentation
test using glucose as the carbon source. Through this test, we
discovered thirty-nine isolates belonging to the generaNakazawaea and Starmerella that exhibited the ability to
ferment glucose. Notably, all of these isolates were obtained from
samples of N. chilensis . This plant is a leguminous tree known
for its high levels of polysaccharides (Astudillo et al. , 2000).
It is also worth mentioning that the ’Aloja’ beverage is produced from
the mashed pods of Neltuma species, suggesting a potential
association between ethanol-tolerant yeasts and the spontaneous
fermentation processes associated with this tree species. Among the
isolates, the majority were identified as representatives of the genusNakazawaea (35 isolates). However, the ITS region of these
isolates differed by 16 to 25% in terms of sequence identity from theNakazawaea species currently described (Figure S1 ).
Hence, in this study, we focus on the description of a new fermenting
ascomycetous yeast species, which we have named Nakazawaea
atacamensis sp. nov.