APPLICATION OF ALUMINUM OXIDE NANOPARTICLE IN THE CULTIVATION OF SOME SELECTED ASPERGILLUS SPECIES FOR THE PRODUCTION OF PROTEASE ENZYME

Abstract

Chemicals are being utilized in a variety of businesses globally, which is having a severe impact on people's health. In today's society, environmentally acceptable replacements for these harmful compounds are used. This study applied aluminum oxide nanoparticles in the cultivation of some selected Aspergillus sp. in the production of protease enzyme. Aspergillus niger, Aspergillus terreus and Aspergillus flavus were isolated from the soil sample collected from the biological garden of the Federal University of Technology, Minna, Niger State. The pure isolates were cultivated using potato dextrose agar slant for 10 days. Cymbopogan citratus (lemon grass) was collected from the environment of Federal University of Technology, Minna, Niger State. The fresh lemon grass were diced and twenty-five (25g) was boiled with 200ml of distilled water and the filtrate was used to produce aluminum oxide nanoparticles. The spores of the isolated Aspergillus sp. were inoculated into sterile pre-culture medium that contains the aluminum oxide nanoparticles and was propagated in shake flasks for 24 hours. 7ml of the pre-culture medium was transferred into sterile production medium and propagated in shake flasks for 120 hours at 28°C. The spores of the enhanced Aspergillus sp. were harvested and introduced into the medium composed of (g/l): CaCl2.7H2O (0.4), KH2PO4 (2.5), MgSO4.7H2O (0.5), ZnCl2 (0.1), NaCl (0.3), Casein (2.0) for protease enzyme production. The medium was incubated in a rotary shaker at 150rpm for 72 hours at 30°C. The cultures were centrifuged at 10,000rpm for 10 minutes. The fungal mycelia were removed and the supernatant was used as the enzyme extract. Different pH, ranging from 5.0, 6.0, 7.0, 8.0, 9.0 and 10.0 and different temperatures, ranging from 30º, 40º, 50º, 60º, 70º and 80º were used for the optimization of the protease enzyme. The Aspergillus niger had the highest yield of protease at 50ºC and Aspergillus flavus had the highest yield at pH 6.0.