Development of ultraporous fired bricks as support for yeast cell immobilization

Ultraporous fired bricks (porosities from 56 to 72%) were developed from materials locally available in Nigeria. The grog particle size was used to modulate the porosity of the bricks. The porous bricks produced were then employed as supports for the immobilization of a yeast strain isolated from a local alcoholic beverage, palm wine. The influence of a brick's porosity and particle size on the cell-loading capacity and cell growth inside the fired brick support were studied. The study revealed that a brick's porosity varied linearly with the mean particle size of the grog, increasing from a porosity of 56% at a particle size of 0.805 mm to 72% at a particle size of 0.075 mm. Cell saturation of the surface area available within the support matrix was completed within four hours of contact between the cell and the adsorbing surface especially for the most porous samples. Cell growth was therefore not observed in such cases; however, the less porous samples supported some cell growth upon incubation. Cell holdup was also observed to increase exponentially when either the porosity was increased or the particle size was decreased. The influence of particle size, however, became insignificant at very high porosities.