Production of high concentrations of ethanol from inulin by simultaneous saccharification and fermentation using Aspergillus niger and Saccharomyces cerevisiae

Abstract

Pure nonhydrolyzed inulin was directly converted to ethanol in a simultaneous saccharification and fermentation process. An inulinase-hyperproducing mutant, Aspeigillus niger 817, was grown in a submerged culture at 30°C for 5 days. The inulin-digestive liquid culture (150 ml) was supplemented with 45 g of inulin, 0.45 g of (NH4)2SO4, and 0.15 g of KH2PO4. The medium (pH 5.0) was inoculated with an ethanol-tolerant strain, Saccharomyces cereviswe 1200, and fermentation was conducted at 30°C. An additional 20 g of inulin was added to the culture after 15 h of fermentation. S. cerevisiae 1200 utilized 99%o of the 65 g of inulin during the fermentation, and produced 20.4 and 21.0%Yo (vol/vol) ethanol from chicory and dahlia inulins, respectively, within 3 days of fermentation. The maximum volumetric productivities of ethanol were 6.2 and 6.0 g/liter/h for chicory and dahlia inulins, respectively. The conversion efficiency of inulin to ethanol was 83 to 84% of the theoretical ethanol yield.

Relationship between lipid composition, frequency of ethanol‐induced respiratory deficient mutants, and ethanol tolerance in Saccharomyces cerevisiae

“…The experiments were carried out with a wild type strain, S. cerevisiae 1200, which is a highly ethanol-producing yeast (Chi and Liu 1993;Ohta et al 1993), and a commercial strain of lager yeast, S. cerevisiae AJL 2155 (The Collection of Pure Cultures of Brewing Yeasts, Alfred Jo Ârgensen Laboratory Ltd, Copenhagen, Denmark). The yeast strains were maintained at 4°C on YPD agar (containing l −1 : 20 g glucose, 20 g peptone, 10 g yeast extract and 20 g agar).…”

Extracellular inulinases from Penicillium janczewskii, a fungus isolated from the rhizosphere of Vernonia herbacea (Asteraceae)

“…3.2.1.7)] are stable at high temperatures, a characteristic which is favourable both for the avoidance of microbial contamination and the increase of solubility of the substrate (Ö ngen-Baysal et al 1994). These hydrolases are usually inducible and exo-acting enzymes (Ohta et al 1993), being able to hydrolyse fructose polymers (levan or inulin) and oligosaccharides, such as sucrose and raffinose (Blatch and Woods 1993). As many microbial preparations of inulinase possess remarkable invertase (S) activity accompanying the inulinase activity (I), their catalytic activity is described in terms of I/S or S/I ratios (Vandamme and Derycke 1983;Ettalibi and Baratti 1987).…”

On‐line estimation of biomass through pH control analysis in aerobic yeast fermentation systems

“…Biomass determination is a basic parameter in fermentation processes. Therefore, simple and reliable on-line estimation procedures are highly desirable, particularly in fermentation processes using Saccharomyces cerevisiae (Fiechter et al, 1987;Larsson et al, 1993;Postma et al, 1989;, which is widely used in industry as a source of a variety of products (van Gulik and Heijnen, 1995;Ohta et al, 1993;Sousa et al, 1994).…”