Suitability of magnetic nanoparticle immobilised cellulases in enhancing enzymatic saccharification of pretreated hemp biomass

Abstract

BackgroundPrevious research focused on pretreatment of biomass, production of fermentable sugars and their consumption to produce ethanol. The main goal of the work was to economise the production process cost of fermentable sugars. Therefore, the objective of the present work was to investigate enzyme hydrolysis of microcrystalline cellulose and hemp hurds (natural cellulosic substrate) using free and immobilised enzymes. Cellulase from Trichoderma reesei was immobilised on an activated magnetic support by covalent binding and its activity was compared with that of the free enzyme to hydrolyse microcrystalline cellulose and hemp hurds on the basis of thermostability and reusability.ResultsUp to 94% protein binding was achieved during immobilisation of cellulase on nanoparticles. Successful binding was confirmed using Fourier transform infrared spectroscopy (FTIR). The free and immobilised enzymes exhibited identical pH optima (pH 4.0) and differing temperature optima at 50°C and 60°C, respectively. The K M values obtained for the free and immobilised enzymes were 0.87 mg/mL and 2.6 mg/mL respectively. The immobilised enzyme retained 50% enzyme activity up to five cycles, with thermostability at 80°C superior to that of the free enzyme. Optimum hydrolysis of carboxymethyl cellulose (CMC) with free and immobilised enzymes was 88% and 81%, respectively. With pretreated hemp hurd biomass (HHB), the free and immobilised enzymes resulted in maximum hydrolysis in 48 h of 89% and 93%, respectively.ConclusionThe current work demonstrated the advantages delivered by immobilised enzymes by minimising the consumption of cellulase during substrate hydrolysis and making the production process of fermentable sugars economical and feasible. The activity of cellulase improved as a result of the immobilisation, which provided a better stability at higher temperatures. The immobilised enzyme provided an advantage over the free enzyme through the reusability and longer storage stability properties that were gained as a result of the immobilisation.

Hybrid Nanomaterials of Magnetic Iron Nanoparticles and Graphene Oxide as Matrices for the Immobilization of β-Glucosidase: Synthesis, Characterization, and Biocatalytic Properties

“…enzyme was observed at pH 5.0; a similar pH profile has been reported for the immobilization of bgl on iron magnetic nanoparticles (Abraham et al, 2014), while other studies demonstrated that immobilized bgl on magnetic nanoparticles reaches its maximum activity at pH 4.0 (Ahmed et al, 2013;Zhou et al, 2013). In most cases, the immobilized bgl was found to keep its activity in a pH range from 2.5 to 5.0, indicating that the immobilized enzyme is less sensitive to the modification of the pH than the free enzyme.…”

“…The high surface area of GO leads to specific interactions with the enzyme, which may induce conformational changes in the protein, leading to an increased hydrolytic activity (Serefoglou et al, 2008;Patila et al, 2013). Moreover, the small size of iron nanoparticles, as well as their high specific surface area, increases the flexibility of the enzyme, which in turn induces a high hydrolytic activity (Abraham et al, 2014). This specific combination of interactions with the protein molecules probably does not occur for bgl/γFe alone or for bgl/GO-C 2 -NH 2 , where the activity of bgl is consequently lower.…”

Characteristics of Lignin Fractions from Dilute Acid Pretreated Switchgrass and Their Effect on Cellobiohydrolase from Trichoderma longibrachiatum

“…Compared to other pretreatment methods, by now, this pretreatment method is close to practical application in industrial production due to low chemical cost and utilization with diverse biomass feedstocks including hardwood and agricultural residues (Benjamin et al, 2013;Mesa et al, 2017). Typically, pretreated biomass is then subjected to enzymatic hydrolysis to produce glucose via a mixture of enzymes such as endoglucanase (EG), exoglucanase or cellobiohydrolases (CBHs), and β-glucosidase (Abraham et al, 2014). CBHs are a group of cellulases that can hydrolyze glycosidic linkages at a crystalline surface of cellulose (Igarashi et al, 2009).…”

Algal biotechnology for pursuing omega-3 fatty acid (bioactive) production

“…Various inexpensive carbon sources, such as whey from the dairy industry, processed fruit pulp from the food processing industry (an important resource for recovering nutrients), bread and bakery waste, 20 crude glycerol, 14 oil cake, lignocellulose resource 21 and molasses can be tested for growing novel microalgal strains 22 . Such cost-effective carbon sources may lead to higher or comparative yield to glucose and glycerol, thus decreasing upstream processing costs.…”