Title Production of an Endoinulinase from Aspergillus niger AUMC 9375, by Solid State Fermentation of Agricultural Wastes, with Purification and Characterization of the Free and Immobilized Enzyme
Author Manal M. Housseiny
Address Department of Biological and Geological Sciences, Faculty of Education, Ain Shams University, Roxy, Cairo, 11757 Egypt
Bibliography Journal of Microbiology, 52(5),389-398, 2014,
DOI DOI 10.1007/s12275-014-3561-y
Key Words inulinase production, solid state fermentation, Aspergillus niger, immobilization
Abstract Two different substrates, sunflower (Helianthus annuus L.) tubers and lettuce (Lactuca sativa) roots, were tested. Using a mixture of both wastes resulted in higher production of endoinulinase than either waste alone. Also, ten fungal spe-cies grown on these substrates as inexpensive, carbon sour-ces were screened for the best production of endoinulinase activities. Of these, Aspergillus niger AUMC 9375 was the most productive, when grown on the mixture using a 6:1 w/w ratio of sun flower: lettuce, and yielded the highest levels of inulinase at 50% moisture, 30°C, pH 5.0, with seven days of incubation, and with yeast extract as the best nitrogen source. Inulinase was purified to homogeneity by ion-exchange chro-matography and gel-filtration giving a 51.11 fold purification. The mixture of sunflower tubers and lettuce roots has poten-tial to be an effective and economical substrate for inulinase production. Inulinase was successfully immobilized with an immobilization yield of 71.28%. After incubation for 2 h at 60°C, the free enzyme activity decreased markedly to 10%, whereas that of the immobilized form decreased only to 87%. A reusability test demonstrated the durability of the immo-bilized inulinase for 10 cycles and in addition, that it could be stored for 32 days at 4°C. These results indicate that this inulinase, in the immobilized form, is a potential candidate for large-scale production of high purity fructose syrups.