The manuscript for these proceedings were received by the Publisher: beginning of October 2011

Abstract

In an attempt to elucidate the effect of mixing on the rate and extent of enzymatic hydrolysis of cellulosic substrates, α-cellulose was hydrolysed using a commercial cellulase preparation at varying levels of substrate concentration (2.5, 5 and 7.5% (w/v)) and by using three shaking regimes: continuous at low-speed (25 rpm), continuous at high-speed (150 rpm) and an intermittent regime comprised of high and low-speed shaking intervals. The continuous, high-speed shaking produced the highest conversion yields, whereas the intermittent and low-speed shaking regimes resulted in lower conversions. After 72 h, at all shaking regimes (150 rpm, 25 rpm and intermittent), using a low substrate concentration (2.5%) produced conversion yields (82, 79 and 80%) higher than those obtained at high (7.5%) substrate concentration (68, 63 and 68%). As the substrate concentration increased, the conversion yields at intermittent shaking gradually approached those resulting from high-speed shaking. Thus, it appears that intermittent shaking could be a beneficial process option as it can reduce the mixing energy requirements while producing reasonably high conversion yields.