Cassava (Manihot esculenta Crantz) pulp, produced in large amounts as a by-product of starch
manufacturing, is a major biomass resource in Southeast Asian countries. It contains abundant starch
(approximately 60%) and cellulose fiber (approximately 20%). To effectively utilize the cassava pulp, an
attempt was made to convert its components to ethanol using a sake-brewing yeast displaying glucoamylase
on the cell surface. Saccharomyces cerevisiae Kyokai no. 7 (strain K7) displaying Rhizopus
oryzae glucoamylase, designated strain K7G, was constructed using the C-terminal-half region of
a-agglutinin. A sample of cassava pulp was pretreated with a hydrothermal reaction (140 C for 1 h),
followed by treatment with a Trichoderma reesei cellulase to hydrolyze the cellulose in the sample. The
K7G strain fermented starch and glucose in pretreated samples without addition of amylolytic enzymes,
and produced ethanol in 91% and 80% of theoretical yield from 5% and 10% cassava pulp, respectively