Optimization of fermentation conditions of chitosanase enzyme produced by Aspergillus ornatus

Abstract

The potentiality of 28 fungal species belonging to 10 genera isolated and identified from Egyptian soils to produce chitosanase in their culture filtrates under submerged culture conditions using colloidal chitosan as the sole carbon source were tested. Aspergilli, particularly Aspergillusornatus were distinguished by its capacity to release exo-chitosanase when grown on a selected medium. Best results were achieved after on 7 days incubation at 30°C and pH 5.0. The impact of aeration, mechanical agitation as well as the volume and age of inoculum upon chitosanase and biomass production were also discussed briefly. The present paper gives an account of observations made on the production of chitosanase and biomass in relation to the chemical constituents of fermentation medium. 1% colloidal chitosan followed by crystal chitosan were more initiative for chitosanase production than any other carbon compounds. Peptone (0.45%) followed by yeast extract were the best nitrogen source for both biomass and chitosanase production. The optimum chitosanase and biomass production were achieved on medium containing 0.1% KH2PO4, 0.5% KCl and 0.5% MgSO4.7H2O. The impacts of the levels of glucose and NaCl on both experimental parameters were also examined. In addition, the supplementation of various B-group vitamin and some trace elements individually to the bioprocess caused no significant effects on chitosanase production. However slight inhibition was obtained with a mixture of tested metal ions. The productivity of chitosanase supported by addition of tween 80 as surfactant agent and enhanced on sand and soil extracts than other natural sources investigated.