Saccharomyces uvarum inulyticus var. nov., a new high-concentration ethanol tolerant yeast from rice wine

Abstract

A new alcohol tolerant yeast which had the ability to ferment glucose, galactose, maltose, trehalose, melizitose, α-methyl-d-glucoside, melibiose and raffinose (complete) was isolated from fermented rice wine. This new isolate which was morphologically, culturally and physiologically similar to type species Saccharomyces uvarum Beijerinck was considered as a variety of the species, hence, designated as Saccharomyces uvarum inulyticus var. nov., because of its extraordinary ability to ferment inulin into ethanol and hyper-tolerance to high concentration of ethanol at a wide range of temperature. The new variant produced 21.6%, 20%, 18.6%, and 9.8% v/v ethanol at 15, 20, 30, and 40° C, respectively, when fermentation was carried out by the stepwise addition of sucrose to the synthetic medium. The addition of fungal mycelia into the synthetic medium increased the fermentation rate and ethanol concentration up to 22.4%, 21.8%, 20.1%, and 11.6% v/v at 15, 20, 30, and 40° C, respectively. The new variant was found to grow well at 40° C and did not require any vitamin or growth factor, such as biotin, calcium pantothenate, inositol, niacin, p-aminobenzoic acid, pyridoxine hydrochloride, riboflavin and thiamine hydrochloride for normal growth.