Direct Production of Ethanol from Raw Corn Starch via Fermentation by Use of a Novel Surface-Engineered Yeast Strain Codisplaying Glucoamylase and α-Amylase

Abstract

Direct and efficient production of ethanol by fermentation from raw corn starch was achieved by using the yeast Saccharomyces cerevisiae codisplaying Rhizopus oryzae glucoamylase and Streptococcus bovis ␣-amylase by using the C-terminal-half region of ␣-agglutinin and the flocculation functional domain of Flo1p as the respective anchor proteins. In 72-h fermentation, this strain produced 61.8 g of ethanol/liter, with 86.5% of theoretical yield from raw corn starch.

Versatile microbial surface-display for environmental remediation and biofuels production

“…The engineered strain of starch hydrolyzing yeast, co-displaying glucoamylase and α-amylase, was able to use raw corn starch as a carbon source to produce 61.8 g/l of ethanol in 72 hours [44].…”

Starch and Microbial α-Amylases: From Concepts to Biotechnological Applications

“…Many researchers have reported attempts to resolve this problem by using recombinant glucoamylase-expressing yeasts with the ability to ferment starch to ethanol directly (Kondo et al, 2002). Also, a noncooking fermentation system using a cell surface-engineered yeast strain promises to be very effective in reducing the production costs of ethanol (Shigechi et al, 2004). On the other hand, fermentation of starch to ethanol in one step using co-cultures of two different strains has been suggested and has potential application for the direct bioconversion of starch into ethanol (Zeikus, 1979).…”

Construction of Amylolytic Industrial Strains of Saccharomyces cerevisiae for Improved Ethanol Production from Raw Starch

“…Raw starch also needs to be gelatinized by cooking at a high temperature, and then liquefied by α-amylase (Eksteen et al, 2003). Raw starch degrading enzymes (RSDE) refer to amylases that can hydrolyze raw starch directly, without an additional high energy-consuming process, such as gelatinization (Shigechi et al, 2004). Many genes of filamentous fungi and yeasts that encode for RSDE have been previously expressed in S. cerevisiae (Sun et al, 2010).…”