Immobilized Cell Concentration Research Articles

Biosensor design: microbial loading capacity of acetylcellulose membranes

In the construction of biosensors incorporating probe oxygen electrodes as the biochemical signal transducer, acetylcellulose membranes have proved to be a popular but poorly characterized matrix for microbial cell immobilization. In this report the relationship between immobilized whole microbial cell concentration/mm3 of acetylcellulose membrane and the reduction in oxygen diffusion across the microbial electrode has been determined using enteric bacteria. Total inhibition of oxygen diffusion occurred when the cell concentration was raised from 1×106 to 1×107 cells mm3: equivalent to a microbial cell volume of 1.5% compared to the maximum theoretical matrix volume. To facilitate future biosensor design a biosensor immobilized cell concentration “Bicc” value and a zero oxygen diffusion “ZO2D” value are suggested, and the parameters of immobilized cell concentration, reduction in oxygen diffusion by immobilized cells and microbial cell size are discussed.

Repeated batch production of ethanol from Jerusalem artichoke tubers using recycled immobilized cells of Kluyveromyces fragilis

Recycled immobilized cells of Kluyveromyces fragilis ATCC 28244 were used for repeated batch production of ethanol from the inulin sugars derived from Jerusalem artichoke tubers. Using 10% initial sugar concentration, a maximum ethanol concentration of 48 g/l was achieved in 7 h when the immobilized cell concentration in the Ca alginate beads was 72 g dry wt. immobilized cell/l bead volume. The maximum ethanol production rate was 13.5 g ethanol/l bioreactor volume/h. The same Ca alginate beads containing the cells were used repeatedly for 11 batch runs starting with fresh medium at the beginning of each run. The ethanol yield was found to be almost constant at 96% of the theoretical for all 11 batch runs, while the maximum ethanol production rate during the last batch run was found to be 70% of the original ethanol rate obtained in the first batch run.