RESUMO
Bioremediation is the most effective green protocol for degradation of environmental contaminants. Present study involves carrier free urease immobilization with synthesis of its new crosslinked aggregates using two different crosslinkers, divinyl benzene (DVB) and tripropyleneglycol dimethacrylate (TPGDA) via free radical mechanism. Resulting crosslinked ureases were further converted to nanoform (CLUNAs) using solvent evaporation technique. The activity of free and the crosslinked ureases was studied as a function of operational parameters viz. temperature (20-80), pH (2-11) and substrate concentration (5-20 mM) using urea as substrate at contact time of 10 min. Storability study of the pristine urease and CLUNAs was carried out for 40 days, and the CLUNAs were reused in 10 repeat cycles to assess their reusability. Isoproturone degradation was studied under the above-cited range of pH and temperature and results were recorded after 24 h.
RESUMO
Immobilization of enzymes to improve their catalytic properties is an attractive protocol which makes them suitable candidates to meet various industrial demands. Present study describes the synthesis of new acryloyl crosslinked cellulose dialdehyde (ACCD) for nitrilase immobilization. Nitrilase was immobilized onto ACCD via Schiff base formation i.e. imine linkages (-CH=N-). Effect of different operational parameters viz. temperature, pH and substrate concentration on the free and the immobilized nitrilases were evaluated by hydrolysis of mandelonitrile. Immobilization resulted into enhanced catalytic activity of nitrilase under different operating conditions of temperature and pH. The optimum temperature and pH for immobilized forms of nitrilase was obtained to be 55⯰C and 8.0 which was higher than its free form (40⯰C, 6.0). Immobilized nitrilase also exhibited good thermal and storage stability over the free form and is reusable up to sixteen repeat cycles with an appreciable retention activity.