In this study, a tailor-made biocatalyst consisting of a co-immobilized lignolytic enzyme cascade on multi-functionalized magnetic silica microspheres (MSMS) was developed. Physical adsorption was the most promising strategy for the synthesis of individual immobilized laccase (IL), immobilized versatile peroxidase (IP), as well as co-immobilized laccase (Lac) and versatile peroxidase (VP) with an enzyme activity recovery of about 79, 93, 27, and 27.5%, respectively. Similarly, the biocatalytic load of 116, 183, 23.6, and 31 U/g was obtained for IL, IP, and co-immobilized Lac and VP, respectively. The co-immobilized enzyme system exhibited better pH stability than the free and individual immobilized system by retaining more than 100% residual activity at pH 7.0 after a 150-h incubation; whereas, the thermal stability and kinetics of the co-immobilized biocatalyst were not much improved. IL and IP could be recycled for 10 cycles after which they retained 31 and 44% of their initial activities. Co-immobilized Lac and VP were reused for ten consecutive cycles at the end of which Lac activity was depleted, and 37% of VP activity was left. Free enzymes, IL, IP, co-immobilized Lac, and VP were applied to biorefinery wastewater (BRW) in a batch study to investigate the transformation of phenolic contaminants over a period of 5 days. The major classes of phenolic constituents in terms of their order of removal in a Lac-VP system was phenol >2-chlorophenol > trichlorophenol > dichlorophenol > cresols > dimethylphenol >2 methyl- 4, 6-dinitrophenol > 4-nitrophenol > tetrachlorophenols > pentachlorophenol. The free enzymes and individually immobilized enzymes resulted in 80% dephenolization in 5 days. By contrast, the co-immobilized biocatalyst provided rapid dephenolization yielding the same 80% removal within 24 h and 96% removal of phenols in 60 h after which the system stabilized, which is the major advantage of the co-immobilized biocatalyst. ᅟ Graphical abstract.
In recent times, inulinase has emerged as one the most prominent and industrially upcoming enzymes applied to meet the ever increasing demand of d-fructose and fructooligosaccharides (FOS) as sweetener and prebiotics in the food and pharmaceutical industry, respectively. This review deals with types of inulinase and the attempts made to modify it for better thermal stability and shelf life. The ease of immobilization of inulinase has led us to the path of experimenting with different methods of enzyme immobilization since 1979. Several modes of immobilization ranging from simple cross-linking of enzymes onto a polymer support to nanoparticles have been applied over the years. The approach and concept of this review provide a yet unexplored focus on pioneering advances for the development of white biotechnology, for instance production of immobilized inulinase-based reusable biocatalysts and bioreactors designed for their use and for the continuous production of fructose and FOS.
AbstractThe novelty of the current study deals with the application of magnetic nanosorbent, chitosan-coated magnetic nanoparticles (cMNPs), to be utilized for the management of lignocellulosic bio-refinery wastewater (LBW) containing three heavy metals and 26 phenolic compounds. The magnetic property of the adsorbent, confirmed by elemental and vibrating sample magnetometer analysis (saturation magnetization of 26.96 emu/g), allows easy separation of the particles in the presence of an external magnetic field. At pH 6.0, with optimized adsorbent dosage of 2.0 g/L and 90 min contact time, maximum removal of phenol (46.2%), copper (42.2%), chromium (18.7%) and arsenic (2.44%) was observed. The extent of removal of phenolic compounds was in the order: polysubstituted > di-substituted > mono-substituted > cresol > phenol. Overall, the adsorption capacity (qe) of cMNPs varies among the different contaminants in the following manner: copper (1.03 mg/g), chromium (0.20 mg/g), arsenic (0.04 mg/g) and phenol (0.56 mg/g). Post-adsorption, retrieving the cMNPs using an external magnetic field followed by single-step desorption via acid–base treatment is attractive for implementation in industrial settings. Reusability of the adsorbent was studied by recycling the cMNPs for five consecutive rounds of adsorption followed by desorption, at the end of which, cMNPs retained 20% of their initial adsorption capacity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.