IMMOBILIZATION OF ACINETOBACTER-JOHNSONII CELLS WITHIN ALGINATE BEADS

The growth and distribution of A. johnsonii cells, immobilised within alginate beads suspended in an aerated activated sludge mixed liquor m edium, were assessed by viable cell counts on nutrient agar and scanni ng electron microscope (SEM). Both techniques indicated that A. johnso nii cells did survive and grow within alginate beads. A. johnsonii imm obilised cells were metabolically active as they removed phosphate fro m the activated sludge mixed liquor medium. While cells were expected to occur preferably in the outer layer after a few hours of incubation , beads entrapping bacterial cells showed a random distribution of cel l colonies 24 h and 2 weeks after incubation. This constant random dis tribution might be attributed to constant aeration would have facilita ted mass transfer added to extracellular substances which maintained d aughter cells in the colonies close to one another, thus preventing th em from moving to the outer layer.