## 3 Results and Discussion
### Physiological Characterization
#### 3.2.5 Properties of Temperature Tolerance of the Selected Yeasts  
The temperature tolerance of the tested strains was evaluated under conditions of 15 \({}^{\circ}\)C, 25 \({}^{\circ}\)C, and 35 \({}^{\circ}\)C. The results are shown in Figure 2E. Significant differences in growth performance were observed among the strains at different temperatures (_p_ < 0.05). At a low temperature (15 \({}^{\circ}\)C), CICC 1004 exhibited the highest OD\({}_{600}\) value (1.90 \(\pm\) 0.02), which was significantly higher than that of the other strains. The OD\({}_{600}\) value of _Pichia kudriavzevii_ GAAS-JG-1 was 1.34 \(\pm\) 0.01, slightly lower than those of CICC 31838 and CICC 31399 (_p_ < 0.05). As the temperature increased to 25 \({}^{\circ}\)C, the growth performance of _Pichia kudriavzevii_ GAAS-JG-1 improved significantly, with an OD\({}_{600}\) value of 1.95 \(\pm\) 0.01, second only to CICC 31838 (2.12 \(\pm\) 0.02), and higher than CICC 1004 (OD\({}_{600}\) = 1.58 \(\pm\) 0.03) and CICC 31399 (OD\({}_{600}\) = 1.86 \(\pm\) 0.01) (_p_ < 0.05). At a higher temperature (35 \({}^{\circ}\)C), _Pichia kudriavzevii_ GAAS-JG-1 achieved its highest growth performance, with an OD\({}_{600}\) value of 2.21 \(\pm\) 0.02, significantly higher than all the control strains (_p_ < 0.05). CICC 31838 followed with an OD\({}_{600}\) value of 2.09 \(\pm\) 0.01, while CICC 1004 and CICC 31399 exhibited weakergrowth, with OD\({}_{600}\) values of 1.38 \(\pm\) 0.01 and 1.93 \(\pm\) 0.02, respectively. In conclusion, _Pichia kudriavzevii_ GAAS-JG-1 demonstrated strong adaptability to varying temperature conditions, maintaining good growth performance at moderate temperatures (25 \({}^{\circ}\)C) and achieving optimal biomass at elevated temperatures (35 \({}^{\circ}\)C). The remarkable temperature adaptability of _Pichia kudriavzevii_ GAAS-JG-1 confirms its suitability for fermentation processes conducted across a wide temperature range. Notably, its superior performance at higher temperatures underscores its physiological adaptability, as also reported in previous studies on _P. kudriavzevii_ in diverse fermentation environments [11; 13].  
The Effect of Pichia kudriavzevii GAAS-JG-1 on Volatile Flavor Compounds in Fermented Sea Buckthorn Wine  
Volatile flavor compounds are key components that contribute to the characteristic flavor profile of fermented sea buckthorn wine, exerting a decisive influence on its sensory quality. In this study, the volatile compounds in sea buckthorn wines produced via two fermentation modes were systematically analyzed: JS (single fermentation with _Saccharomyces cerevisiae_ CICC 32168) and JH (co-fermentation with _S. cerevisiae_ CICC 32168 and _Pichia kudriavzevii_ GAAS-JG-1). A total of 48 esters, 18 alcohols, 7 acids, 3 aldehydes/ketones, and a small number of other flavor compounds were identified (Table S1 and Figure 3). The synthesis and transformation of these compounds under different fermentation conditions not only directly influenced the aroma and taste of the wine but also played a crucial role in its overall flavor balance. The results indicated that compared to single-strain fermentation (JS group), mixed fermentation (JH group) significantly altered the distribution of volatile compounds. This finding suggests that _Pichia kudriavzevii_ GAAS-JG-1 has a notable impact on the synthesis and transformation of flavor compounds during sea buckthorn wine fermentation. The following sections provide a detailed classification and analysis of the changes observed in various types of volatile flavor compounds.