Evaluation of fermentation performance of yeast strains isolated from Passiflora ligularis

This study aimed to identify high-performing yeast strains suitable for the fermentation of Passiflora ligularis wine (PLW). A total of thirty indigenous yeast isolates were obtained from spontaneous fermentation samples of P. ligularis fruit. Strain selection was conducted through systematic evaluation of key oenological traits, including CO₂ evolution rate, ethanol yield, ester synthesis capacity, hydrogen sulfide (H₂S) production, and antagonistic activity against common spoilage microorganisms. Based on these criteria, several strains with excellent fermentation performance have been selected. Molecular identification confirmed that one isolate belonged to Saccharomyces cerevisiae (designated FSQ-1), while the remaining seven were non-Saccharomyces yeasts, six strains of Pichia kluyveri and one strain of Hanseniaspora uvarum. Comprehensive stress tolerance profiling revealed that all eight strains exhibited robust growth under challenging enological conditions: temperature range 4-40 °C, pH 2.5, high osmolarity (400 g/L sucrose), elevated ethanol concentration (12% v/v), and high SO₂ levels (400 mg/L). Furthermore, all strains efficiently assimilated standard carbon sources and nitrogen sources. Collectively, S. cerevisiae FSQ-1 demonstrated the most favorable combination of fermentation efficiency, metabolic stability, and stress resilience, positioning it as the leading candidate starter culture for PLW production. This work contributes to the development of regionally adapted, functionally characterized yeast resources for PLW manufacturing.