Inulin is a type of fructose polymer that is commonly present in plants as a storage carbohydrate. Enzymatic hydrolysis of inulin via exo-inulinase to produce fructose is an efficient, green and state-of-the-art technique. To achieve the high-level secretory expression of inulinase and to realize enzymatic preparation of fructose syrup from inulin, an Aspergillus exo-inulinase gene inu was codon-optimized and co-expressed with the endoplasmic reticulum secretion protein in Pichia cells. After inducible expression in a 500-L pilot scale bioreact...