Immobilization of Bacillus circulans MTCC 7906 for enhanced production of alkaline protease under batch and packed bed fermentation conditions

Abstract

Alkaline protease production by immobilized cells of Bacillus circulans MTCC 7906 was studied using agar-agar and calcium alginate as entrapment materials. Under batch conditions using agar agar, 2% agar concentration, 6.25mm bead size and 200 beads/ flask inoculum size were the optimal conditions for a maximum alkaline protease production of 19.9 IU/ml and while for alginate beads, 3% alginate concentration, 5.2mm bead size and 200 beads/ flask inoculum size were the optimal conditions for a maximum alkaline protease production of 19.7 IU/ml. The alginate and agar agar beads were reusable for four and nine successive batch cycles respectively. A maximum enzyme production of 28 and 27 IU/ml was obtained with incubation time of 36 h, column length of 30cm and flow rate of 10ml/h with agar-agar and alginate entrapped cells respectively under packed bed fermentation conditions. Scanning electron microscopy (SEM) of the agar agar entrapped cells showed a random distribution of cells on the surface with pockets of high cell density.