Abstract
The utilization of renewable biomass resources to produce high-value chemicals by enzymatic processes is beneficial for alternative energy production, due to the accelerating depletion of fossil fuels. As immobilization techniques can improve enzyme stability and reusability, a novel magnetic cross-linked cellulase aggregate has been developed and applied for biomass bioconversion. The cross-linked aggregates could purify and immobilize enzymes in a single operation, and could then be combined with magnetic nanoparticles (MNPs), which provides easy separation of the materials. The immobilized cellulase showed a better activity at a wider temperature range and pH values than that of the free cellulase. After six cycles of consecutive reuse, the immobilized cellulase performed successful magnetic separation and retained 74% of its initial activity when carboxylmethyl cellulose (CMC) was used as the model substrate. Furthermore, the structure and morphology of the immobilized cellulase were studied by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Moreover, the immobilized cellulase was shown to hydrolyze bamboo biomass with a yield of 21%, and was re-used in biomass conversion up to four cycles with 38% activity retention, which indicated that the immobilized enzyme has good potential for biomass applications.
Highlights
Lignocellulosic biomass, the most abundant and bio-renewable resource on the Earth, has attracted worldwide attention with the limitation of fossil fuels and environmental concerns [1]
cross-linked enzyme aggregates (CLEAs), and magnetic-cellulase-CLEAs are given in stretch in the peak 569 chemical cm−1 appeared in Figure 1c,d, which indicated the structure of Fe3 O4 was preservedatafter corresponds to the vibrations of the magnetite core
That may be attributed to the immobilization scaffold, which prevented stretching of the enzyme in magnetic-cellulase-CLEAs was hindered at lower temperatures
Summary
Lignocellulosic biomass, the most abundant and bio-renewable resource on the Earth, has attracted worldwide attention with the limitation of fossil fuels and environmental concerns [1]. It is necessary to seek a greener and more efficient method for converting cellulose to glucose [1] Among these methods, hydrolysis catalyzed by cellulase has shown an attractive application potential, since it has mild reaction conditions, high yield conversion, and is environmentally friendly [14]. The immobilization of cellulase on magnetic nanoparticles (MNPs) by the adsorption method can retain the structure of enzyme very well, but the weak interaction may lead to the leakage of the enzyme from the support, which influences the stability and reusability [21]. Cross-linked enzyme aggregates (CLEAs) have emerged as novel and versatile biocatalysts, which are prepared and are effective with high stability [27,28].
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