Abstract:
Inulinase is an enzyme that cleaves the β-2,1 fructosidic bond of inulin to produce fructose. Currently, inulinase has received more attentions and widely used in industrial food processing. Garlic is known as available agricultural source with high inulin content. Therefore, the researcher has been interested in screening of microorganisms that capable producing inulinase from garlic cloves and dehydrated garlic pulp. In preliminary screening of inulinase producing fungi, 10 isolated fungi able to generate clear zones on selective media. Fungal isolated from garlic cloves were 6 isolates, such as IS1, IS2, IS4, IS7,IS11, and IS13, while 4 isolates from dehydrated garlic bulbs, such as IS3, IS5, IS8 and IS10. Analysis the inulinase activity of these isolates found that IS13 showed the highest enzymatic activity at 0.109±0.006 Unit/ml. Identification of this fungal strain by molecular technique using ITS sequence was found that IS13 showed 100% identity to Penicillium citrinum strain NZD-mf99 (GenBank accession number KM278047.1). For increasing the inulinase production, optimum condition was determined. It was found that the P. citrinum IS13 growing in selective medium supplemented with 20g/L of inulin, adjust pH to 5.5 and culture for 7 days could produce the highest inulinase activity at 0.128±0.006 Unit/ml which higher than control condition approximately 17.43%. Interestingly, not only pure inulin, the fungal P. citrinum identified in this study could be used dried garlic residue as a carbon source for producing the inulinase.