ABSTRACT
Atacama is the most hyper-arid Desert in the world. In this study, we
describe a novel species, Nakazawaea atacamensis f. a., sp. nov.,
isolated from plant samples in the Atacama Desert of Chile. In total,
three isolates of N. atacamensis were obtained from independentNeltuma chilensis bark samples (synonym Prosopis chilensis,
Algarrobo). The novel species was delineated based on morphological,
physiological, biochemical, and molecular characteristics. A
neighbour-joining analysis using the sequences of the D1/D2 domains of
LSU rRNA revealed that N. atacamensis sp. nov. clustered withNakazawaea pomicola . The sequence of N. atacamensisdiffered from closely related species by 1.3% to 5.2% in the D1/D2
domains. A phylogenomic analysis based on single nucleotide
polymorphism’s data confirms that the novel species belongs to the genusNakazawaea, and placed N. atacamensis closer to N.
peltata . Phenotypic comparisons demonstrated that N. atacamensissp. nov. exhibited distinct carbon assimilation patterns compared to its
related species. Genome sequencing of the ATA-11A-BTstrain revealed a genome size of approximately 12.4 Mbp, similar to
other Nakazawaea species, with 5,116 protein-coding genes
annotated using InterProScan. In addition, N. atacamensisexhibited the capacity to ferment synthetic wine must, representing a
potential new yeast for mono or co-culture wine fermentations. This
comprehensive study expands our understanding of the genusNakazawaea and highlights the ecological and industrial potential
of these yeasts in fermentation processes. The holotype of N.
atacamensis sp. nov. is CBS 18375T. The Mycobank
number is MB 849680.
INTRODUCTION
Yeasts are known for their ubiquitous presence in various biomes, where
they inhabit a wide range of substrates and environments. These include
tropical forests (Morais et al. , 2006), temperate forests
(Mozzachiodi et al. , 2022), hyperarid deserts, and cold habitats
(Buzzini et al. , 2018). Hyperarid desert habitats are
characterized by challenging conditions such as low oxygen and water
levels, extreme temperatures, and exposure to ultraviolet (UV) radiation
(Houston & Hartley, 2003, Schulze-Makuch et al. , 2018). To
survive in these conditions, yeasts have evolved various adaptation
mechanisms. For instance, they produce carotenoid pigments and
mycosporines to withstand UV radiation, and possess aquaporins to
counteract sudden osmotic changes (Aponte-Santamaría et al. ,
2017). However, despite the importance of yeast diversity and their
metabolic capacity to tolerate environmental stresses and nutrient
limitations, most studies in hyperarid deserts have focused on bacteria,
neglecting the role of yeasts, especially in extreme environments such
as deserts (Drees et al. , 2006, Finstad et al. , 2017,
Azua-Bustos et al. , 2018).
Exploring microbial diversity in inhospitable habitats represents a
promising strategy for discovering novel yeast species with valuable
biotechnological potential. In this regard, ethanol-tolerant yeasts
demonstrated remarkable abilities that revolutionized biotechnology
industries, for example by providing biological and genetic resources
for the production of novel beverages with unique organoleptic
properties (Libkind et al. , 2011, Cubillos et al. , 2019).
For instance, a recent bioprospecting study conducted in the Patagonian
rainforest led to the identification of new Saccharomycesspecies, including S. eubayanus , which has proven valuable for
the brewing industry (Libkind et al. , 2011, Peris et al. ,
2016, Eizaguirre et al. , 2018, Nespolo et al. , 2020).
Similarly, the recent advent of non-Saccharomyces species from
natural environments is becoming an interesting biological resource to
develop novel fermented beverages (Canonico et al. , 2019,
Villarreal et al. , 2022). However, the occurrence and diversity
of culturable yeasts in other environments, particularly hyper-arid and
desert areas, have been largely overlooked (Wei et al. , 2022).
The Atacama Desert, situated in northern Chile (19º-27ºS), stands as the
driest and oldest desert on Earth, representing an extreme environment
for life (Ewing et al. , 2006). The central valley is classified
as a hyper-arid desert with an average annual precipitation of less than
20 mm. The Atacama Desert experiences daily temperature fluctuations
ranging from -6 °C to 38 °C (McKay et al. , 2003). Moreover, it is
characterized by intense UV radiation, limited organic carbon sources,
and low water availability (Navarro-González et al. , 2003).
Despite these harsh conditions, a few resilient woody plants and
perennial grasses manage to thrive in this environment (Carrasco‐Pugaet al. , 2021). Similarly, the Atacama Desert soil harbours
diverse microorganisms, particularly in surficial salt crusts (Wierzchoset al. , 2011) and in association with plants (Eshel et
al. , 2021). Previous studies have predominantly focused on bacteria in
the field of Astrobiology, aiming to gain fundamental insights into
terrestrial desert environments and their microbiota (Azua-Bustoset al. , 2012, Pulschen et al. , 2015). However,
investigations on yeast communities associated with the flora of the
Atacama Desert, thriving under extremely arid conditions, remain scarce.
Historically, the indigenous people of the Atacama region have used
various plants to produce spontaneously fermented beverages, which
typically exhibit low ethanol levels. These beverages are created
through the natural fermentation of leguminous tree pods and fruit
juices, providing a source of calories, proteins, vitamins, minerals,
and diverse bioactive compounds (Sciammaro et al. , 2016). For
instance, ‘Aloja’ is an alcoholic beverage made by fermenting mashed
pods of the Neltuma (synonym Prosopis ) tree, locally known
as Algarrobo (Pardo O., 2015, Sciammaro et al. , 2022). This
practice suggests the presence of indigenous ethanol-tolerant yeasts
within naturally fermented musts, indicating a promising opportunity for
the discovery of novel fermentative yeasts within the local vegetation
of the Atacama Desert.
In this study, our objective was to isolate ethanol-tolerant yeasts
associated with the flora of the Atacama Desert using an enrichment
culture strategy. We successfully obtained three yeasts isolates from
different tree samples, one of them from bark-exuded gum and two from
barks obtained from independent N. chilensis trees. Further
investigations revealed that these isolates represent a previously
unidentified yeast species. Morphological and physiological
characteristics, as well as phylogenetic analyses, provide strong
support for classifying these three strains as a new ascomycetous yeast
species within the genus Nakazawaea . We propose the nameNakazawaea atacamensis sp. nov. for this novel species.
Furthermore, we demonstrate the potential fermentation utilization of
this species.