Balwinder Singh Sooch and Baljinder Singh Kauldhar
Catalase (EC 1.11.1.6) is a metalloenzyme belonging to the class of oxidoreductases which catalyze the degradation of hydrogen peroxide into dioxygen and water. Catalase, an important enzyme in the world market has wide range of industrial applications. In one of the important application, it is used to degrade unused hydrogen peroxide from wastewater released after bleaching operations in the textile industry. The use of catalase enzyme in soluble form is not feasible because of many economical and technical limitations. Therefore, the use of immobilized whole cells of bacterium having intracellular catalase activity is advantageous due to their repeated use, but it suffers from a drawback of instability and leakage of cells after some time. In the present study, sodium alginate beads used to immobilize Bacillus sp. TE-5 cells was modified to increase their stability and tested for the degradation of H2O2 in batch and continuous mode. The effect of other critical factors like sodium alginate concentration, bacterial cell load, glutaraldehyde concentration and treatment time for hardening beads was investigated to test their suitability for long term repeated operations. Maximum catalase activity (15900 IU/g of cells) was achieved by using modified sodium alginate beads cross linked with glutaraldehyde (0.10%, w/v) with CaCl2 treatment time of 18 hr. The reusability of beads in a batch mode was studied to test their potential for continuous operations and then these immobilized cells were further used in a packed bed reactor for the degradation of H2O2 in continuous mode. These results provide an indication that this method of gel entrapment followed by cross-linking could be an effective, stable and better alternative for degradation of H2O2 in continuous system.
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