Immobilization of Aspergillus Niger cellulase onto Lifetech TM carriers and its application in the hydrolysis of sunflower seed meal lignocellulosic fraction

Abstract

Cellulases are enzymes which catalyse cellulose hydrolysis and are widely used in various industry branches. Lately, their application in treatment of different agroindustrial waste materials which could serve for fuel production is being extensively explored. In order to increase their stability and cost-effectiveness of their usage, application of their immobilized forms are preferred over free enzymes. Hereby, we tested eight different LifetechTM immobilization supports differing in polarity, porosity and functional groups as carriers for Asspergillus Niger cellulase immobilization. Most promising carrier was methacrylate based, with primary amino groups, C6 "space arm" and pores with diameter of 60-120 nm - LifetechTM ECR8409F. For this support, most important immobilization parameters were investigated and after 3 h at pH 6 with initial protein concentration of 23.3 mg/g support immobilized cellulase with 406 IU/g (with carboxymethyl cellulose as a substrate) was obtained. This preparation was successfully applied in the hydrolysis of lignocellulosic fraction of sunflower seed meal, which is widely available byproduct of sunflower seed meal fractionation for protein-rich fractions production. Initial reaction rates and yields of reducing sugars were unchanged comparing to free enzyme, indicating that there were no significant diffusion limitations for substrate to approach active sites of A. Niger cellulase molecules immobilized onto LifetechTM ECR8409F support.

Celulaze su enzimi koji katalizuju hidrolizu celuloze i u širokoj su primeni u brojnim granama industrije. U poslednje vreme, mogućnost njihove primene u tretiranju različitih opadnih agroindustrijskih sirovina u cilju dobijanja biogoriva intenzivno se istražuje. Da bi se povećale stabilnost i ekonomičnost njihove primene, potrebno je umesto slobodnog enzima koristiti imobilisane forme. U ovom istraživanju osam LifetechTM nosača različitih polarnosti, poroznosti i funkcionalnih grupa. testirano je za imobilizaciju celulaze producenta Aspergillus Niger. Najpogodniji nosač bio je na bazi metakrilata, sa primarnim amino grupama, C6 "dugom nožicom" i porama prečnika 60-120 nm - LifetechTM ECR8409F. Za ovaj nosač određeni su najznačajniji uslovi imobilizacije i nakon 3 sata na pH 6, pri početnoj koncentraciji proteina od 23,3 mg/g nosača dobijena je imobilisana celulaza aktivnosti 406 IU/g (sa karboksi metil celulozom kao supstratom). Ovaj preparat uspešno je primenjen u reakciji hidrolize lignocelulozne frakcije suncokretove sačme, koja prestavlja nusproizvod frakcionisanja suncokretove sačme pri dobijanju frakcija bogatih proteinima. Početne brzine reakcije i prinosi redukujućih šećera bili su nepromenjeni u odnosu na slobodan enzim, ukazujući da nije bilo značajnog uticaja difuzionih limitacija pri prilasku supstrata aktivnim centrima molekula A. Niger celulaze imobilisane na LifetechTM ECR8409F nosač.