Peroxidase of Cedrela fissilis leaves: Biochemical characterization and toxicity of enzymatically decolored solution of textile dye Brilliant Sky-Blue G

Enzymatic characterization and application of soybean hull peroxidase as an efficient and renewable biocatalyst for degradation of zearalenone

Zearalenone (ZEN) is a notorious mycotoxin commonly found in Fusarium-contaminated crops, which causes great loss in livestock farming and serious health problems to humans. In the present work, we found that crude peroxidase extraction from soybean hulls could use H2O2 as a co-substate to oxidize ZEN. Molecular docking and dynamic simulation also supported that ZEN could bind to the active site of soybean hull peroxidase (SHP). Subsequently, SHP extracted from soybean hulls was purified using a combined purification protocol involving ammonium sulfate precipitation, ion exchange chromatography and size exclusion chromatography. The purified SHP showed wide pH resistance and high thermal stability. This peroxidase could degrade 95 % of ZEN in buffer with stepwise addition of 100 μM H2O2 in 1 h. The two main ZEN degradation products were identified as 13-OH-ZEN and 13-OH-ZEN-quinone. Moreover, SHP-catalyzed ZEN degradation products displayed much less cytotoxicity to human liver cells than ZEN. The application of SHP in various food matrices obtained 54 % to 85 % ZEN degradation. The findings in this study will promote the utilization of SHP as a cheap and renewable biocatalyst for degrading ZEN in food.

Mechanism of action, sources, and application of peroxidases

Peroxidase is an enzyme in the group of oxidoreductases that is widely distributed in nature. It can catalyze the oxidation of various organic and inorganic substrates by reacting with hydrogen peroxide and similar molecules. Due to its wide catalytic activity, peroxidases can act in the removal of both phenolic compounds and peroxides, in chemical synthesis and, according to recent studies, in mycotoxin degradation. Therefore, this study aimed at introducing an overview of the mechanism of peroxidase action, extraction sources, mycotoxin degradation capacity and other potential applications in the food industry.

Nanostructured materials for harnessing the power of horseradish peroxidase for tailored environmental applications

High catalytic efficiency, stereoselectivity, and sustainability outcomes of enzymes entice chemists for considering biocatalytic transformations to supplant conventional synthetic routes. As a green and versatile enzyme, horseradish peroxidase (HRP)-based enzymatic catalysis has been widely employed in a range of biological and chemical transformation processes. Nevertheless, like many other enzymes, HRP is likely to denature or destabilize in harsh realistic conditions due to its intrinsic fragile nature, which results in inevitably shortened lifespan and immensely high bioprocess cost. Enzyme immobilization has proven as a prospective strategy for improving their biocatalytic performance in continuous industrial processes. Nanostructured materials with huge accessible surface area, abundant porous structures, exceptional functionalities, and high chemical and mechanical stability have recently garnered intriguing research interests as novel kinds of supporting matrices for HRP immobilization. Many reported immobilized biocatalytic systems have demonstrated high catalytic performances than that to the free form of enzymes, such as enhanced enzyme efficiency, selectivity, stability, and repeatability due to the protective microenvironments provided by nanostructures. This review delineates an updated overview of HRP immobilization using an array of nanostructured materials. Furthermore, the general physicochemical aspects, improved catalytic attributes, and the robust practical implementations of engineered HRP-based catalytic cues are also discussed with suitable examples. To end, concluding remarks, challenges, and worthy suggestions/perspectives for future enzyme immobilization are also given.

Green synthesis of silver nanoparticles transformed synthetic textile dye into less toxic intermediate molecules through LC-MS analysis and treated the actual wastewater

The illegal disposal of waste from textile industries having recalcitrant pollutants is a worldwide problem with more severity in developing nations. We used an ecofriendly method to synthesize silver nanoparticles (AgNPs) from a locally-isolated bacterial strain Bacillus marisflavi TEZ7 and employed them as photocatalysts to degrade not only synthetic azo dyes but also actual textile effluents followed by phytotoxicity evaluation and identification of degradation molecules. The strain TEZ7 was taxonomically identified through the 16S rRNA gene sequence analysis. Biogenic AgNPs were characterized for stabilizing molecules, crystal structure, size, shape and elemental composition by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), respectively. The photocatalytic degradation efficiency of biogenic AgNPs for three azo dyes such as Direct Blue-1, Methyl Red, and Reactive Black-5 ranged between 54.14 and 96.92% after 5 h of sunlight exposure at a concentration of 100 mg/L. Moreover, the actual wastewater treatment analysis revealed that the 100 mg/L dose of AgNPs significantly decreased the concentration of various physico-chemical parameters of textile effluents such as pH, EC, chlorides, sulphates, hardness, BOD, COD, TSS and TDS. Furthermore, six intermediate molecules of methyl red degradation were identified by LC-MS and it was established by a pot study that these degradation molecules have no phytotoxic effects on rice plants. It was concluded that the AgNPs can be used as an efficient and low-cost strategy for the degradation of azo dyes containing textile wastewaters.

Immobilization of Low-Cost Alternative Vegetable Peroxidase (Raphanus sativus L. peroxidase): Choice of Support/Technique and Characterization

In the present work the radish (Raphanus sativus L.) was used as the low-cost alternative source of peroxidase. The enzyme was immobilized in different supports: coconut fiber (CF), calcium alginate microspheres (CAMs) and silica SBA-15/albumin hybrid (HB). Physical adsorption (PA) and covalent binding (CB) as immobilization techniques were evaluated. Immobilized biocatalysts (IBs) obtained were physicochemical and morphologically characterized by SEM, FTIR and TGA. Also, optimum pH/temperature and operational stability were determined. For all supports, the immobilization by covalent binding provided the higher immobilization efficiencies-immobilization yield (IY%) of 89.99 ± 0.38% and 77.74 ± 0.42% for HB and CF, respectively. For CAMs the activity recovery (AR) was of 11.83 ± 0.68%. All IBs showed optimum pH at 6.0. Regarding optimum temperature of the biocatalysts, HB-CB and CAM-CB maintained the original optimum temperature of the free enzyme (40 °C). HB-CB showed higher operational stability, maintaining around 65% of the initial activity after four consecutive cycles. SEM, FTIR and TGA results suggest the enzyme presence on the IBs. Radish peroxidase immobilized on HB support by covalent binding is promising in future biotechnological applications.