Partial purification of crude Psuedomonas aeruginosa IZ cellulase enzyme was carried out by ammonium sulfate fractionation (85%). The specific activity of cellulase increased 493.3% (from 0.15 U/ml protein in the crude enzyme to 0.89 U/ml protein after ammonium sulfate treatment) while the unit protein was decreased 21.9% (from 48.5 mg/ml in the crude enzyme to 37.9 mg/ml after ammonium sulfate treatment) with activity preservation and a purification fold of 5.93. Further purification of the partially purified enzyme was achieved using anion exchange chromatography on DEAE sephadex A-50. The cellulase activity was enriched after this step of purification; the specific activity increased 301.1 % (from 0.89U/ml protein after ammonium sulfate treatment to 3.57 U/ml protein after anion exchange chromatography) with a purification fold of 23.8. The protein was reduced by 56.99 % (from 37.9 after ammonium sulfate treatment to 16.3 after anion exchange chromatography). The highest active cellulase fractions obtained from anion exchange chromatography on DEAE sephadex A-50 were loaded on a Sephadex G-100 column for Gel filtration chromatography. The specific activity of cellulase was further increased by 85.71 % (3.57 U/ml protein after anion exchange chromatography to 6.63 U/ml after gel filtration) with purification factor fold of 44.2 and protein decreased by 39.26 % (from 16.3mg/ml after anion exchange chromatography to 9.9 mg/ml after gel filtration chromatography). The optimum pH and incubation temperature for the purified Psuedomonas aeruginosa IZ cellulase enzyme were 6.5 and 35˚C respectively. The enzyme kinetics studies indicated that the enzyme activity is dependent on the concentration of the substrate. When the relation between the enzyme activity and the substrate concentration was treated by Lineweaver-Burk analysis, it was found that Km and Vmax were 4 mg/ml and 7.2 U/ml respectively.
Keywords: Characterization, Psuedomonas aeruginosa IZ, Purification, cellulase, corn cobs
