Preliminary Analysis of Sugar Supplementation on Alcoholic Fermentation by <i>Meyerozyma guilliermondii</i>

Abstract

Non Saccharomyces yeast strains consume a diverse range of sugars, capable of producing ethanol at different quantities and concentrations. The ability of such wild type indigenous strains to do so and compete with industrial strains of Saccharomyces cerevisae is not common in Nigeria. This study aimed at comparing the ability of Meyerozyma guilliermondii with a strain of Saccharomyces cerevisiae, to consume sugars (fructose, galactose, glucose, lactose, sucrose and molasses) and to convert them into ethanol during fermentation. Yeast extract (6g/L), peptone (10g/L), malt extract (6g/L) broth was supplemented with different concentrations (5g/L, 10g/L, 20g/L, 30g/L) of fructose, galactose, glucose, lactose and sucrose respectively. Sugar utilization post incubation for 96 hours at 120 rpm, 30°C was measured using a refractometer. The alcoholic yield using molasses for Meyerozyma guilliermondii 9.2±0.45 (mg/ml) was significantly higher than that of Saccharomyces cerevisiae strain T (4.8±1.15 mg/ml) at 96 hours. Ethanol production from the consumption of fructose as the sole carbon source was more favourable for M. guilliermondii 2.1, 3.0, 8.11 and 9.06 (mg/ml) compared to 1.08, 3.12, 8.06 and 6.0 (mg/ml) for S. cerevisiae. Both strains displayed similar adaptation to galactose metabolism at all tested concentrations. With glucose, M. guilliermondii yielded more than its S. cerevisiae counterpart at 1.0% (4.15, 3.18 mg/ml) and 2.0% glucose (4.25, 3.3 mg/ml). At 3.0% glucose broth content, 8.15 and 9.08 mg/ml ethanol was obtained for M. guilliermondii and S. cerevisiae respectively. Sucrose utilization resulted in a 10.18 mg/ml yield of ethanol compared to a 7.06 mg/ml yield for M. guilliermondi and S. cerevisiae respectively at 3.0% sugar supplement. Meyerozyma guilliermondii displayed its ability as a highly adaptable non Saccharomyces yeast specie capable of producing ethanol from a variety of sugars indicative of local feedstock as a suitable alternative.