Ningxia is one of the well-known wine producing regions in China. However, the oenological and aroma characteristics of indigenous yeasts remains hidden. The fermentative and oenological properties including stress resistance, hydrogen sulfide, foam production levels; killer phenotype, and flocculation of 89 Ningxia indigenous Saccharomyces cerevisiae isolates and ten commercial yeasts were evaluated. The fermentative and oenological properties of the tested strains varied significantly. They could resist 500 g/L glucose, 300 mg/L SO₂, 14% (v/v) ethanol and pH 2.8, and produce more esters. They also produce low levels of ethanol and could conduct fermentations vigorously and at a high rate. Cabernet Sauvignon wines made with NXU 21–24 showed the high intensity of tropical fruit, dry fruit, temperate fruit, and spicy flavor. The floral flavor in NXU 21–102 fermented wine is very intense. The indigenous S. cerevisiae strains of NXU 21–102 and NXU 21–24 exhibited potential use as starter cultures in wine production.

The organoleptic profile and quality of wine are affected by the presence of different non-Saccharomyces species and strains. Therefore, the identification and characterization of non-Saccharomyces yeasts are the first step to understand their function, and to develop a better strain selection program for winemaking. This study investigated the biodiversity of non-Saccharomyces yeasts associated with spontaneous fermentation of Cabernet Sauvignon wines from five sub-regions (Shi Zuishan, Yinchuan, Yu Quanying, Qing Tongxia and Hong Sibu) in Ningxia, China. Yeast species were identified by sequencing the 26S rRNA D1/D2 region, and strains at the subspecies level were discriminated using tandem repeat-tRNA (TRtRNA) PCR analysis. A total of 524 yeast colonies were isolated, and 19 non-Saccharomyces yeast species belonging to 10 genera were identified, including Aureobasidium pullulans, Cryptococcus albidus, Cryptococcus sp., C. flavescens, C. terrestris, C. magnus, Cystofilobasidium ferigula, Candida zemplinina, Filobasidium magnum, Filobasidium sp., F. elegans, Hanseniaspora uvarum, Metschnikowia pimensis, M. pulcherrima, Naganishia albida, Pichia kluyveri, P. kudriavzevii, Rhodotorula glutinis and R. graminis. Hanseniaspora uvarum, C. zemplinina, and M. pulcherrima were the three most dominated species, while other non-Saccharomyces species were only present in the early stage of spontaneous fermentations at different levels. Further, for the yeast discrimination at strain level, 34 profiles were obtained by amplification with primer pairs TtRNASC/5CAG, while 40 profiles were obtained with primer pairs TtRNASC/ISSR-MB. This study explored the diversity of non-Saccharomyces species in Ningxia, China, and made an important contribution of genetic resources for further strain development.

In this study, three fermentation treatments of spontaneous fermentation (SF), direct inoculation of CECA (YF), and inoculation with CECA after addition of dimethyl dicarbonate (YDF) were carried out. Multivariate statistical analysis approved that CECA inoculation significantly influenced the composition of 141 metabolites (15 volatile organic compounds (VOCs) and 126 non-VOCs), mainly consisting of 36 acids and derivatives and 25 lipids and lipid-like molecules. YF and YDF wines exhibited similar correlations with aroma types, while there were differences in the kinds and number of VOCs. Moreover, CECA-inoculated fermentation was more favorable to the formation of aftertaste-A, umami, sourness, and richness. The KEGG metabolic pathway analysis indicated that the inoculation strategy significantly affected the amino acid metabolism. The antimicrobial treatment effectively enhanced bitterness, astringency, umami and saltiness while reducing acidity. Further studies are needed to assess the effects of antimicrobial treatment on lipid metabolism.

Hanseniaspora uvarum is a representative non- Saccharomyces species that plays a significant role in fermentation processes such as winemaking. In recent years, this species has gained attention in food engineering and evolutionary biology. However, the population genomic signatures in this species remain poorly understood. In this study, a population genomics analysis was conducted on 151 H. uvarum strains (45 from Ningxia, China; 21 from other regions of China; 67 from Australia; and 18 from other regions or of unspecified origin), and a pangenome analysis was performed on 159 strains, incorporating eight additional genome assemblies. Phylogenetic analysis, ancestry coefficient analysis, and principal component analysis generally distinguished Chinese strains from those sampled on other continents. However, substantial post-divergence gene flow and introgression were inferred between intercontinentally paired clades. Positively selected candidate genes exhibited region-specific patterns: GO terms related to the positive regulation of filamentous growth in response to external stimuli were significantly enriched in the Ningxia strains; the stress-related GO term “cytoplasmic stress granule” was significantly enriched in both the Ningxia and Australian strains, but with distinct sets of associated genes. Although the samples were primarily isolated from anthropogenic environments, H. uvarum exhibited an open pangenome, indicating substantial adaptive potential to diverse stresses. This study advances our understanding of the evolutionary dynamics of H. uvarum and establishes a genomic foundation for future ecological and industrial research on this yeast.

During the winemaking process, the dominance of commercial active dry yeasts (ADYs) influence the interactions among microorganisms and the profiles of wine aroma. In this study, the implantation percentage of ADYs, fungal diversity and volatile profiles during the industrial Cabernet Sauvignon wine fermentation from four wineries in Ningxia, China were investigated. Four species were identified by the culture-dependent method. A total of 38 volatile aromas were identified through headspace solid phase microextraction gas chromatography mass spectrometry. Interdelta sequence typing showed that FX10 strain used in Winery2 had a lower implantation percentage than that of IONYS-WF strain used in Winery4 during fermentation. High-throughput sequencing further elucidated differences in fungal community structures at different fermentation times between Winery2 and Winery4. Correlation analyses between microbial communities and flavor components highlighted the role of dominant species in shaping characteristic flavor profiles. This study deepens comprehension of how ADYs influence fungal succession and wine characteristics.