Studies On Fermentation, Alcohol Production And Viability In Induced Mutants Of The Brewing Yeast Saccharomyces cerevisiae

Abstract

Brewing yeast, Saccharomyces. Cerevisiae cultured on malt extract agar was UV-irradiated. Eighteen mutant yeasts (SCM 01 – SCM 18) selected (after visual examination) were tested for fermentation, alcohol production and viability by acid and gas production, reduction in specific gravity and turbidity respectively, with sugars and delignified sugarcane bagasse. The yeasts had varied fermentation profiles in glucose, sucrose, galactose, dextrose and mannitol but did no ferment lactose. Glucose, sucrose and galactose were fermented strongly with acid and gas production. Dextrose was fermented weakly by SCM 01, SCM 06, SCM 09 and SCM 10 (with acid production only) but strongly by all other yeasts. The wild type yeast did not ferment mannitol but SCM 04 did so strongly and SCM 02, SCM 03, SCM 06, SCM 07, SCM 09, SCM 10 and SCM 13 did so weakly. Specific gravity fell sharply within 36h after inoculation and slightly thereafter. Alcohol production varied among the yeasts. Some mutants produced more alcohol than the wild type yeast. Viability was generally lower in the mutants than in the wild-type yeast in the sucrose medium. The reverse was true in the sugarcane bagasse medium. Yeasts with high viability tended to have high alcohol production ability in the sucrose medium and vice-versa.

KEY WORDS: Alcohol production; fermentation; induced mutants; Saccharomyces cerevisiae; viability.

Global Journal of Pure and Applied Sciences Vol.11(1) 2005: 1-7