β-Glucan production of Saccharomyces cerevisiae in medium with different nitrogen sources in air-lift fermentor

Abstract

β-Glucan is one of the most abundant polysaccharides in yeast Saccharomyces cerevisiae cell wall. The aim of this research is to explore an alternative nitrogen sources for β-glucan production. S. cerevisiae were grown in fermentation medium with different nitrogen sources. Peptone 2%, glutamic acid 0,5%, urea 0,2%, and diammonium hydrogen phosphate (DAHP) 0,02% were used for nitrogen source in the medium. A two liter air-lift fermentor was used in the fermentation process for 84 hours (T = 300C, pH 7, and 1.5 vvm for the aeration). During the fermentation, optical density, extraction of β-glucan, glucose and protein in hydrolisate cultured were determined. β-glucan production level is similar with the growth rate of yeast and followed by decreasing glucose and protein content in hydrolysis cultured. The highest and lowest β-glucan content were obtained from peptone (933.33 mg/L) and glutamic acid (633.33 mg/L) as a nitrogen source in cells cultured after fermentation completed respectively. Yeast cells cultured with urea and DAHP as a nitrogen source give the same content of β-glucan about 733.33 mg/L. β-glucan concentration produced in medium with urea was a higher than that produced using
glutamic acid and DAHP as a nitrogen source. The result indicated that urea can be used as an alternative nitrogen source for the
production of β-glucan. Urea is easily available and cheaper than peptone, glutamic acid and DAHP.
© 2007 Jurusan Biologi FMIPA UNS Surakarta

Key words: β-glucan, Saccharomyces cerevisiae, air-lift fermentor