Pichia kudriavzevii yeast cell wall as a novel source of β-glucan: Extraction, characterization, and prebiotic functionality.

In this study, β-glucan extraction was optimized from the Pichia kudriavzevii M10 strain, which was randomly selected from five yeast candidates (M5, M10, M13, M16, and M57). The goal was not only to maximize extraction yield but also to thoroughly characterize the structural and functional properties of the obtained β-glucan. β-glucan yields from cell walls were evaluated under optimized extraction conditions (inoculation, autolysis, hot water, sonication, and protease). Among the five yeast strains initially screened, P. kudriavzevii M13 exhibited the highest β-glucan content (87.8%) and was therefore selected for the optimization process and further analysis of its prebiotic properties. Fermentability of β-gluM13 by Ligilactobacillus plantarum GD2, Bifidobacterium bifidum A12, and Saccharomyces cerevisiae BD1 was assessed. Viability of these strains increased in media with β-gluM13 as the sole carbon source compared to controls. Lactobacillus Growth-Promoting (LGP), Bifido Growth-Promoting (BGP), and Yeast Growth-Promoting (MGP) activities of β-gluM13 at 0.5-10 mg/mL were compared with inulin. The highest LGP, BGP, and MGP activity were designated in the media containing 10 mg/mL (9.4 ± 0.1 log CFU/mL), 5 mg/mL (9.4 ± 0.1 log CFU/mL), and 10 mg/mL (9.4 ± 0.3 log CFU/mL) β- gluM13, respectively. Antioxidant activity of β-gluM13 (0.2-50 mg/mL) was measured via DPPH (2,2-diphenyl-1-picrylhydrazil) assay, showing lower activity than ascorbic acid. Gastrointestinal stability was tested in simulated gastric and bile fluids; β-gluM13 exhibited minimal hydrolysis (1.14% at 5 mg/mL, pH 2, 180 min; 1.16% at 10 mg/mL, 0.5% bile). β-gluM13's notable LGP, BGP, and MGP activities, moderate antioxidant properties, and gastrointestinal stability suggest its potential for gut health and functional food applications.