EFFICIENT PRODUCTION OF ETHANOL BY CELLS IMMOBILIZED IN LOOFA (LUFFA-CYLINDRICA) SPONGE

Both flocculating and non-flocculating cells were immobilized in loofa (Luffa cylindrical sponge and used for continuous ethanol production in column-type bioreactors. Immobilization of non-flocculating cells ( Candida Brassicae) was achieved by addition of chitosan to the reactor . However, the amount of immobilized non-flocculating cells per unit s ponge was lower, and consequently the volumetric ethanol productivity was about 20% less than that of the flocculating cells. In comparison with a fixed bed made of a single cylindrical loofa sponge, the amount of sponge per unit reactor volume was 2 times higher when sliced loof a sponge was used to construct the fixed bed. Furthermore, the use of sliced loofa sponge resulted in 2- and 4-fold increases in the amount of immobilized flocculating and non-flocculating cells per unit sponge , respectively. Consequently, higher volumetric ethanol productivities were obtained when sliced loofa sponge was used for bed construction. In the case of flocculating (Saccharomyces cerevisiae IR-2) cells, th e volumetric ethanol productivity was 66% higher than that obtained wi th a cylindrical loofa sponge.