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

Glutaraldehyde functionalization of halloysite nanoclay enhances immobilization efficacy of endoinulinase for fructooligosaccharides production from inulin

Current work describes the enhancement of immobilization efficacy of Aspergillus tritici endoinulinase onto halloysite nanoclay using crosslinker glutaraldehyde. Under statistical optimized immobilization conditions, viz. glutaraldehyde 1.50% (v/v), enzyme coupling-time 2.20 h, glutaraldehyde activation-time 1.00 h and endoinulinase load 50 IU, maximum activity yield (65.77%) and immobilization yield (82.45%) was obtained. An enhancement of 1.15- and 1.23-fold in both enzyme activity yield and immobilization yield of endoinulinase was observed, when compared with APTES-functionalized halloysite nanoclay immobilized endoinulinase. Immobilized biocatalyst showed maximum activity at pH 5.0 and temperature 60 °C with broad pH (4.0-8.5) and temperature (50-75 °C) stability. Further, optimal hydrolytic conditions (inulin concentration 8.0%; endoinulinase load 80 IU; agitation 125 rpm and hydrolysis-time 13 h) supported fructooligosaccharides yield (95.44%) in a batch system. HPTLC studies blueprint confirmed 95.44% fructooligosaccharides containing 35.41% kestose, 26.19% nystose and 9.69% fructofuranosylnystose. The developed immobilized biocatalyst shown good stability of 8 cycles for inulin hydrolysis.

Industrial applications of immobilized nano-biocatalysts

Immobilized enzyme-based catalytic constructs could greatly improve various industrial processes due to their extraordinary catalytic activity and reaction specificity. In recent decades, nano-enzymes, defined as enzyme immobilized on nanomaterials, gained popularity for the enzymes' improved stability, reusability, and ease of separation from the biocatalytic process. Thus, enzymes can be strategically incorporated into nanostructured materials to engineer nano-enzymes, such as nanoporous particles, nanofibers, nanoflowers, nanogels, nanomembranes, metal-organic frameworks, multi-walled or single-walled carbon nanotubes, and nanoparticles with tuned shape and size. Surface-area-to-volume ratio, pore-volume, chemical compositions, electrical charge or conductivity of nanomaterials, protein charge, hydrophobicity, and amino acid composition on protein surface play fundamental roles in the nano-enzyme preparation and catalytic properties. With proper understanding, the optimization of the above-mentioned factors will lead to favorable micro-environments for biocatalysts of industrial relevance. Thus, the application of nano-enzymes promise to further strengthen the advances in catalysis, biotransformation, biosensing, and biomarker discovery. Herein, this review article spotlights recent progress in nano-enzyme development and their possible implementation in different areas, including biomedicine, biosensors, bioremediation of industrial pollutants, biofuel production, textile, leather, detergent, food industries and antifouling.

Inulinase Immobilized Lectin Affinity Magnetic Nanoparticles for Inulin Hydrolysis

In this presented paper, concanavalin A-modified cysteine-functionalized Fe₃O₄/Ag core/shell magnetic nanoparticles were synthesized and used as a support material for inulinase enzyme, which has been intensively used for the preparation of high-fructose syrup by hydrolyzing inulin. Inulinase adsorption capacity of Con A-functionalized Ag-coated magnetic nanoparticles was optimized by changing medium pH, temperature, and initial inulinase concentration, and maximum inulinase adsorption capacity was found to be 655.32 mg/g nanoparticle by using 1.00 mg/mL of inulinase solution in pH 3.0 buffer system at 25 °C. Finally, efficient inulin degradation capacity of the inulinase immobilized magnetic nanoparticles was demonstrated by TLC studies and released fructose amount was determined as 0.533 mg/mL only within the 5 min of hydrolysis. This newly developed hydrolysis strategy holds considerable promise to produce high-fructose syrup in many industries.

Fructose production from inulin using fungal inulinase immobilized on 3-aminopropyl-triethoxysilane functionalized multiwalled carbon nanotubes

The main objective of the present work was to modify multiwalled carbon nanotubes (MWCNTs) using 3-aminopropyl-triethoxysilane (APTES) to generate amino-terminated surfaces for inulinase immobilization, which can be further used for fructose production. CCRD of response surface methodology was used for optimization of inulinase immobilization on MWCNTs. At optimized parameters (APTES concentration 4%; sonication time 4 h; enzyme coupling time 1.5 h and enzyme load 15 IU), maximal inulinase activity and immobilization yield was 60.7% and 74.4%, respectively. Immobilized inulinase showed same pH optima of free enzyme, while an elevation in temperature optima to 60 °C was observed after its immobilization. Immobilized inulinase also shown enhancement in pH stability and thermostability. Overall, 4.54-fold rise in half-life of inulinase was detected after immobilization at 60 °C. K_m and V_max of inulinase decreased after immobilization. Immobilized inulinase preserved 28% of its residual activity after 10 consecutive batch cycles of inulin hydrolysis for the production of fructose.