Production and immobilization of invertase from Penicillium sp. using orange peel waste as substrate

Abstract

Background and objective Invertases represent a group of industrially important enzymes that catalyze the breakdown of sucrose into fructose and glucose. The objective of the present work was the production of invertase enzyme from Penicillium spp. using orange peel waste as substrate under optimum conditions, and also immobilization and characterization of invertase using chitin as carrier. Materials and methods The fungal strain Penicillium spp. and Trichoderma viride were studied for invertase production using different agricultural wastes as substrate. Some parameters such as concentrations of substrate, incubation time, and inoculum size affecting invertase produced by Penicillium spp. using orange peel as substrate were investigated. The invertase produced by Penicillium spp. was partially purified with acetone (60%). Different carriers such as chitin, foam, and saw dust were used for invertase immobilization by covalent binding. The characterizations of immobilized invertase on chitin such as substrate concentrations, pH values, temperature, time of the reaction, thermal stability, and some metal ions were determined. Results and conclusion On comparison between production of invertase from Penicillium spp. and T. viride using different agricultural wastes, it was found that Penicillium spp. produced the highest amount of invertase in the presence of 5% w/v orange peel waste as the carbon source (0.63 U/ml). The optimum incubation period for invertase production was observed after seventh day of incubation periods, using two disks 4 mm in diameter, which produced maximum invertase activity of 1.98 U/ml. The crude enzyme from Penicillium spp. was partially purified by 60% acetone and produced 0.44 U/ml, and then immobilized invertase by covalent binding on chitin showed the highest immobilized yield (88.1%). Overall, 5.0 mg of sucrose as substrate gave the highest activity yield. The optimum conditions for immobilized invertase were at pH 6.0, 30°C, after 30 min of the reaction time; the highest immobilization yields of invertase were 93.2, 98.1, and 100.2%, respectively. The immobilized invertase was completely stable at 50°C, for 30 min Moreover, tryptone, alumina, l-serine and hydroxyproline, zinc sulfate, and EDTA enhanced the yield of invertase immobilized with 182.7, 165.1, 137.7, 134.8, 117.6, and 108.2%, respectively.