Immobilization of inulinase from Aspergillus niger on octadecyl substituted nanoporous silica: Inulin hydrolysis in a continuous mode operation

Abstract

Inulinase hydrolyzes inulin and produce high fructose syrup in a single-step reaction. However, finding the best working conditions and the highest inulinase stability, especially in continuous mode operations are of critical value. Native (endo-inulinase (EC 3.2.1.7)) and chemically modified inulinases (endo-inulinase stabilized with pyridoxal 5'-phosphate /ascorbic acid in a semi-rational chemical modification approach) were immobilized on octadecyl substituted nanoporous silica (with the average pore size of 66 nm) by using dioxane to extend the hydrophobic interactions between inulinase refolding intermediates and the hydrophobic alkyl moieties of the support. Native and modified inulinases revealed their maximum surface hydrophobicity at 40 and 50 % dioxane in water, respectively. Immobilized inulinases (native and modified) showed 7.89 and 3.73 fold increase in their half lives compared to the free native sample., higher reusability compared to free inulinases (native and modified) and also could retain their activities after 10 hydrolysis cycles in a continuous mode of experimental conditions.

Screening of Ligninolytic Fungi and Optimization of Pretreatment Process for Bioethanol Production from Empty Palm Oil Bunches (OPEFB)

“…In the pretreatment process, fungi can act in various mechanisms, including in changing the crystallinity structure of cellulose. The increase and decrease of crystallinity index (Table 2) by fungal pretreatment is due to the breaking of inter-and intra-chain hydrogen bonds of cellulose brils damages cellulose crystals, and the biomass is more accessible during enzymatic hydrolysis (Karimi et al 2016). Exoglucanase can disrupt the crystal structure of cellulose and convert long molecular chains into soluble short molecular fragments.…”

“…5). This will make it more accessible for the substrate to be accessed by enzymes during hydrolysis (Karimi et al 2016). Meanwhile, A. terreus, T. viride, and A. niger increased the CCI.…”