## 1 Introduction  
Assyrtiko is a Greek grape variety with unique sensorial attributes. This dynamic variety is famous worldwide due to the production of high-acidity wines, with typical varietal aromas, even more so when grown in the volcanic terror of Santorini Island [1]. Assyrtiko is considered a variety that is well adapted to climate change, characterized by resistance to heat and drought. Recently, a great collection of wine yeast has been collected from Greek wines at the end of the fermentation process, including Assyrtiko wines [2]. The wine market is becoming extremely competitive, so an effort to differentiate and create a signature wine style is vital [3]. The role of microorganisms constitutes an integral modulator of wine quality [4, 5]. Modern winemaking seeks and invests in the selection of so-called indigenous, autochthonous, or native local strains. Indigenous strains are believed to be able to maintain the typical sensory properties and enhance the unique properties of a wine, demonstrating improved adaptation to their native environment [6]. Complexity can be added through the inoculation of various species either under co-inoculation or sequential inoculation schemes [7, 8, 9].  
Non-_Saccharomyces_ yeasts are usually found in the early stages of alcoholic fermentation, and the most dominant ones belong to the genera of _Hanseniaspora_, _Candidida_, _Torulaspora_, _Pichia_, _Rhodotorula_, and _Zyogosaccharomyces_[4, 10]. These non-_Saccharomyces_ yeasts may play a positive role in wine quality through the production of secondary metabolites with enhanced sensorial contribution [11; 12; 13]. A new application of non-_Saccharomyces_ has emerged in terms of bioprotection, aiming for a reduction in sulfite in wines [11]. Furthermore, their ability to increase the release of volatile thiols, particularly during the pre-fermentation stage, when this microbiological sub-population is dominant, was previously noted [12]. In any case, their low fermentation capacity and high sensitivity to alcohol make them inappropriate starters for wine fermentation. Thus, mixed cultures with _S. cerevisiae_ strains designed, leading to more or less complex wines based on the yeast strains and winemaking conditions [14; 15; 16]. Non-_Saccharomyces_ yeast can also be classified as spoilage wine agents. The species that are most at risk of provoking organoleptic deviation is _Brettanomyces bruxellensis_, through the production of active odorous compounds that are described as \"horse sweat\", \"animal\", \"plastic\", etc. Volatile phenols are the main compounds implicated in the spoilage effect, which can also be produced by genera such as _Candida_, _Pichia_, and _Trigonopsis_[17; 18; 19]. In more detail, _Trigonopsis_ species were shown to be able to grow in the presence of ethanol by expressing heat shock proteins and a DNA damage-related protein and to be able to confer spoilage characteristics on wine [17]. Additionally, _Pichia_ species that are recovered from grapes, grape juice, and winery equipment that is in contact with grape juice, but not from wines, produced 4-ethylphenol, an unpleasant taint described as a \"phenolic odor\" [19].  
The present study aims to evaluate the performance of indigenous and rarely isolated non-_Saccharomyces_ strains in monoculture fermentation schemes for their enological potential. Namely, the previously isolated species _Zygosaccharomyces bailii_, _Pricenomyces carsonii_, _Trigonopsis california_, and _Pichia manshurica_[2] were tested for their fermentation capacity and their sensorial contribution to Assyrtiko must. All the aforementioned species, based on the bibliography, are often correlated with microbial spoilage and have never before been evaluated for any beneficial potential.