As reported in a previous paper [8], R. oryzae cells form
a dense film near the surface of the polyurethane foam BSPs
(6-mm cubes) and are rarely present inside the particles due to
oxygen starvation in immobilized cell culture. This observation
indicates that, to improve lipase activity per unit volume of BSP
and thereby the volumetric ME productivity in a PBR using R.
oryzae cells immobilized within BSPs as whole-cell biocatalyst,
the specific surface area of the BSPs must be increased. In the
present study, we examined the use of 6mm×6mm×3mm
cuboidal polyurethane foam BSPs to immobilize R. oryzae
cells. When cultured with the cuboidal BSPs in a 20-l air-lift
bioreactor, R. oryzae cells became well immobilized within
the BSPs as a natural consequence of their growth during
batch cultivation. The effect of particle size and shape on
methanolysis reaction was then investigated