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.