The tyrosinase of Penicillium chrysogenum strain AUMC 14100 Accession No. MN219732 was purified to homogeneity and chemically modified by N-ethylmaleimide (NEM) and 5-(dimethylamino)naphthalene-1-sulfonyl chloride (dansyl chloride, DC). The inactivation of the purified enzyme obeyed pseudo-first-order reaction kinetics in the presence of NEM and DC (1-5 mM).The rate constants of the enzyme inactivation by NEM and DC were calculated to be 0.083 mol/min and 0.0013 mol/min, respectively. The recovery of enzyme activity by the protective effect of substrate indicates a non-specific modification of the active center. The order of tyrosinase inactivation kinetics and the substrate protection revealed the essentiality of sulfhydryl and lysyl residues in the enzyme active site and its role in the enzyme catalysis. The immobilized tyrosinase on alginate showed a gradual increase in residual activity over the immobilization time until the fourth hour. The desorptivity of tyrosinase was gradually raised with higher sodium dodecyl sulfate (SDS) concentrations. The immobilized enzyme retained about 70% of its original activity after 8 repeated cycles. Thus, immobilized tyrosinase of Penicillium chrysogenum removed 75% of phenol after 8 cycles and thus seems likely to be a good candidate for phenol removal in aqueous solution.

Environmental pollution due to the continuous uncontrolled discharge of toxic dyes into the water bodies provides insight into the need to eliminate pollutants prior to discharge is significantly needed. Recently, the combination of conventional chemotherapeutic agents and nanoparticles has attracted considerable attention. Herein, the magnetic nanoparticles (Fe3O4-NPs) were synthesized using metabolites of Aspergillus niger. Further, the surfaces of Fe3O4-NPs were functionalized using 3-mercaptoproionic acid as confirmed by XRD, TEM, and SEM analyses. A purified P. expansum laccase was immobilized onto Fe3O4/3-MPA-SH and then the developed immobilized laccase (Fe3O4/3-MPA-S-S-laccase) was applied to achieve redox-mediated degradation of different dyes. The Fe3O4/3-MPA-S-S-laccase exhibited notably improved stability toward pH, temperature, organic solvents, and storage periods. The Fe3O4/3-MPA-S-S-laccase exhibited appropriate operational stability while retaining 84.34% of its initial activity after 10 cycles. The catalytic affinity (Kcat/Km) of the immobilized biocatalyst was increased above 10-fold. The experimental data showed remarkable improvement in the dyes’ decolorization using the immobilized biocatalyst in the presence of a redox mediator in seven successive cycles. Thus, the prepared novel nanocomposite-laccase can be applied as an alternative promising strategy for bioremediation of textile wastewater. The cytotoxic level of carboplatin and Fe3O4-NPs singly or in combination on various cell lines was concentration-dependent.

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Abstractβ-Glucanase has received great attention in recent years regarding their potential biotechnological applications and antifungal activities. Herein, the specific objectives of the present study were to purify, characterize and immobilize β-glucanase from Aspergillus niger using covalent binding and cross linking techniques. The evaluation of β-glucanase in hydrolysis of different lignocellulosic wastes with subsequent bioethanol production and its capability in biocontrol of pathogenic fungi was investigated. Upon nutritional bioprocessing, β-glucanase production from A. niger EG-RE (MW390925.1) preferred ammonium nitrate and CMC as the best nitrogen and carbon sources, respectively. The soluble enzyme was purified by (NH4)2SO4, DEAE-Cellulose and Sephadex G200 with 10.33-fold and specific activity of 379.1 U/mg protein. Tyrosyl, sulfhydryl, tryptophanyl and arginyl were essential residues for enzyme catalysis. The purified β-glucanase was immobilized on carrageenan and chitosan with appreciable yield. However, the cross-linked enzyme exhibited superior activity along with remarkable improved thermostability and operational stability. Remarkably, the application of the above biocatalyst proved to be a promising candidate in liberating the associate lignocellulosic reducing sugars, which was utilized for ethanol production by Saccharomyces cerevisiae. The purified β-glucanase revealed an inhibitory effect on the growth of two tested phytopathogens Fusarium oxysporum and Penicillium digitatum.

The release of different hazardous substances into the water bodies during the industrial and textile processing stages is a serious problem in recent decades. This study focuses on the potentiality of Fe3O4-NPs-based polymer in sustainable bioremediation of toxic substances from contaminated water. The biosynthesis of Fe3O4-NPs by A. tamarii was performed for the first time. The effect of different independent variables on the Fe3O4-NPs production were optimized using Plackett–Burman design and central composite design (CCD) of Response Surface Methodology. The optimum Fe3O4-NPs production was determined using incubation period (24 h), temperature (30 °C), pH (12), stirring speed (100 rpm) and stirring time (1 h). The incorporation of Fe3O4-NPs into chitosan beads was successfully performed using sol–gel method. The modified nanocomposite exhibited remarkable removal capability with improved stability and regeneration, compared to control beads. The optimal decolorization was 94.7% at 1.5 g/l after 90 min of treatment process. The reusability of biosorbent beads displayed 75.35% decolorization after the 7th cycle. The results showed a highly significant reduction of physico-chemical parameters (pH, TDS, TSS, COD, EC, and PO4) of contaminated wastewater. The sorption trials marked Fe3O4-NPs-based biopolymer as efficient and sustainable biosorbent for the elimination of hazardous toxic pollutants of wastewater in a high-speed rate.