Screening and identification of potential indigenous yeasts isolated during fermentation of wine coffee

Abstract

Wine coffee is a fermented coffee product that involves yeast as the fermentative agent which has potency as probiotics. This study aimed to determine the potency of yeast isolated from wine coffee fermentation and to identify the yeast species with the best probiotic properties. This study comprised three main steps: coffee fermentation, yeast isolation, and probiotic characterization. A series of probiotic tests were carried out, including resistance tests at low pH (pH 2, 3, & 4) and bile salts (0.5% & 2%), antimicrobial activity tests, antibiotic resistance tests, hemolytic activity tests, and species identification based on the ITS rDNA sequence. The data obtained were analyzed using One-way ANOVA (p≤0.05) and continued with the Tukey test. A total of 25 yeast isolates were isolated and purified. Nine isolates (A2, B1, B3, C3, D4, D5, E2, E3 & E5) had the highest tolerance to pH 2 and 2% bile salts with survival rates were more than 100% and 90%, respectively. Nine isolates were resistant to all tested antibiotics, and only isolate A2 exhibited a pathogenic characteristic (β-hemolysis). Three isolates (B3, E3 & E5) could inhibit the five indicator pathogens, with the highest inhibitory activity shown by isolating E3 against Bacillus cereus by 68 AU/mL. The isolate E3 was selected as the best yeast with probiotic properties identified as Pichia kudriavzevii with 100% similarities towards strain iwate20191107.