Synergistic Interaction Between Kazachstania humilis and Fructilactobacillus sanfranciscensis Modulates Metabolic...

In this study, an acid-tolerant and high-fermentation performance strain of Kazachstania humilis (K. humilis 3-8) was screened from sourdough isolates and co-cultured with Fructilactobacillus sanfranciscensis (F. sanfranciscensis 5) to prepare liquid sourdough, which was further applied in mantou production. The effects on physicochemical properties, nutritional characteristics, and microbial interactions were investigated. K. humilis 3-8 exhibited strong gas production and acid tolerance, achieving a dough volume increase of 72.19% after 3 h fermentation. In co-culture, F. sanfranciscensis 5 maintained stable growth, while its metabolites significantly inhibited the growth of K. humilis 3-8 during mid-fermentation. The co-fermented dough showed decreased pH and increased total titratable acidity. Metabolomic analysis indicated enhanced carbohydrate metabolism and amino acid metabolism, suggesting carbon-nitrogen metabolic interactions between the two strains. When applied to Mantou production, the optimized co-culture system substantially enhanced product functionality, increasing resistant starch content by 76.7% (from 23.02% to 40.68%). Total phenolic content and antioxidant capacity were markedly enhanced. These findings elucidate complex microbial interactions governing sourdough ecosystems and establish a scientific foundation for the targeted improvement of traditional fermented cereal products through rational strain selection and process optimization.