Technological and probiotic potentials of yeasts isolated from fermenting cassava mash for cyanide degradation

Yeasts are predominant microorganisms in cassava-based traditional fermented foods. Fufu and gari are unexplored reservoir for yeast strains that degrade cyanogenic glucosides. Yeasts were isolated from fufu and gari and screened for β-glucosidase production. High enzyme-producing isolates were evaluated for growth at 800 mg/L cyanide and 1.20% lactic acid. Probiotic and cyanide degradation potentials of isolates were determined. A total of 169 yeast isolates were obtained from samples of 9 fufu samples and 8 gari samples. Exactly, 157 isolates produced strain-specific levels of β-glucosidase. Five selected isolates, including-MOGB53, YOGB61, YOGB62, 3MOFA33 and 3YOGA45 demonstrated strain-specific growth indices (34.92-98.42%) at 800 mg/L of cyanide and 34.67 to 63.62% at 1.20% of lactic acid. The selected isolates survived at pH 3.5 (62.50-92.71%) and 0.5% bile salts (36.07-69.34%) and in simulated gastric and intestinal juices. They showed strong autoaggregation (89.10 to 99.60%). In cassava mash fermented with Wickerhamomyces anomalus YOGB62, cyanide content reduced from 40.15 mg/kg to 10.82 mg/kg and an undetectable level after 48 h and 72 h, respectively. This study revealed the occurrence of yeasts in fufu and gari that demonstrated potentials for application as probiotic starter cultures to detoxify cassava-based fermented foods.