Extraction, prebiotic effects and gastrointestinal system resistance of βeta-glucan from Pichia kudriavzevii yeast strains

In this study, it was aimed to optimize the extraction of β-glucan from Pichia kudriavzevii yeast strains and to determine the stability of β-glucan (β-gluM13) obtained from the yeast strain showing the highest β-glucan yield in the gastrointestinal tract with its prebiotic effects. First of all, yeast strain with high growth ability was selected and optimizations in the extraction steps were made to increase the amount of β-glucan. The amount of β-glucan was determined in five different P. kudriavzevii yeast strains under the determined optimum conditions, and the P. kudriavzevii M13 strain showed the highest β-glucan yield (87.8%). The fermentation capacity of β-gluM13 by Ligilactobacillus plantarum GD2, Bifidobacterium bifidum A12 and Saccharomyces cerevisiae BD1 was investigated. The viability of the strains in the medium containing β-gluM13 as a carbon source increased compared to the control medium. Lactobacillus Growth Regulatory (LGD), Bifido Growth Regulatory (BGD) and Yeast Growth Regulatory (MGD) activities of β-gluM13 at different concentrations (0.5; 1; 5; 10 mg/mL) were investigated and combined with commercial prebiotic inulin. The highest LGD, BGD and MGD effects were determined in the mediums 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. The antioxidant effect of β-gluM13 at different concentrations (0.2-50 mg/mL) was determined by the DPPH (2,2-diphenyl-1-picrylhydrazil) method, and the antioxidant activity at all concentrations was lower than that of the positive control (ascorbic acid). The stability of β-gluM13 in the gastrointestinal tract was evaluated according to their hydrolysis in artificial gastrointestinal fluids at different concentrations (0.5-10 mg/mL). 5 mg/mL β-gluM13 had the highest percentage of hydrolysis (1.14%) at pH 2 (180 min), and 10 mg/mL β-gluM13 had the highest percentage of hydrolysis at 0.5% bile concentration (1.16%). β-gluM13 has the potential to be used as a prebiotic due to its high LGD, BGD, MGD activity, antioxidant properties and resistance to gastrointestinal fluids.