Isolation, identification, and kinetic and thermodynamic characterization of a Pichia kudriavzevii yeast strain capable of fermentation

Abstract

Meeting the demand for novel alcoholic beverages implies seeking innocuous yeasts that generate ethanol abundantly and give good taste and fragrance to the final product. For the yeasts isolated to date, there are few reports on the kinetics and thermodynamics of ethanol production, despite the key role this compound plays in accelerating fermentation. The aim of the current contribution was to isolate yeast strains from sugarcane and soil, select the innocuous ones that best produce and tolerate ethanol while growing on malted barley as substrate, and then determine their kinetic/thermodynamic parameters by evaluating cell growth, ethanol production, and substrate consumption over time and at different temperatures (10–40 °C). Saccharomyces cerevisiae 8A and Pichia kudriavzevii 4A exhibited 9.55% v/v and 20% v/v tolerance to ethanol, respectively. P. kudriavzevii 4A was chosen for the kinetic/thermodynamic study, conducted under an oxygen-limited condition (as exists in fermentation). Yeast growth and substrate consumption were best predicted by the Gompertz model, and ethanol production by the Luedeking–Piret model. P. kudriavzevii 4A showed a great tolerance to ethanol and a high level of ethanol production at all temperatures tested. These properties are invaluable economically and technically in industrial fermentation for the elaboration of alcoholic beverages.