To study and compare the morphology of the phellinoid Agaricomycetes strains and find other strategies to improve Phellinus spp. growth and metabolism. In this study, the morphological characteristics of four Phellinus igniarius strains (phellinoid Agaricomycetes) were observed under a light microscope. The exudates from these fungi were observed using light microscopy, scanning electron microscopy (SEM), and energy-dispersive spectrometry (EDS). The exudates were initially transparent with a water-like appearance, and became darker with time at neutral pH. Microscopy of air-dried exudates revealed regular shapes and crystals. Cl- (chloride) and K+ were the two key elements analyzed using EDS. Polyphenol oxidase (POD), catalase (CAT), and laccase activities were detected in mycelia from each of the four Phellinus strains. The K+ content of the three strains was higher than that of the wild strain. Cl- content correlated negatively with that of K+. Laccase activities associated with each mycelia and its corresponding media differed under cold and contaminated conditions.

Copper selenide nanoparticles (CuSeNP) were synthesized using histidine, ethylenediamine, and sodium selenate as precursors by one-step microwave digestion methods. The as-prepared CuSeNPs exhibit excellent catechol oxidase mimic enzyme and catalase (CAT)-like activities. Dopamine (DA) can be oxidized to aminochrome with H2O2 by CuSeNPs, and the intermediate product aminochrome can further react with α-naphthol to yield a highly fluorescent derivative. It was confirmed that Cr(III) could adsorb on the surface of CuSeNPs and inhibit the production of semiquinone radicals in the reaction system, and the catalytic activity of CuSeNPs was inhibited. The detection mechanisms, kinetics, and catalytic properties of CuSeNPs were systematically investigated. As a result, a novel fluorescence method for the assay of Cr(III) was established. The feasibility of CuSeNP nanozyme in detecting speciation Cr(III) in food samples was explored with satisfactory results. It showed the obvious potential for developing effective and dependable fluorescent detection method for protecting food safety.

Copper metalloenzymes ascorbate oxidase (AOase), amine oxidase (AmOase), and catechol oxidase (COase) possess copper(II) sites of coordination, which are trimeric, homodimeric, and dimeric, respectively. Two newly mononuclear copper(II) complexes, namely, [Cu(L)(bpy)](ClO4) (1) and [Cu(L)(phen)](ClO4) (2) where HL = Schiff base, have been synthesized. UV-visible, EPR and single-crystal X-ray diffraction examinations were used to validate the geometry in solution and solid state. For complex 1, the metal exhibits a coordination sphere between square pyramidal and trigonal bipyramidal geometry (τ, 0.49). A positive CuII/I redox potential indicates a stable switching between CuII and CuI redox states. Despite the monomeric origin, both homogeneous catalysts (1 or 2) in MeOH were found to favor three distinct chemical transformations, namely, ascorbic acid (H2A) to dehydroascorbic acid (DA), benzylamine (Ph-CH2-NH2) to benzaldehyde (Ph-CHO), and 3,5-di-tert-butylcatechol (3,5-DTBC) to 3,5-di-tert-butylquinone (3,5-DTBQ) [kcat: AOase, 9.6 (1) or 2.0 × 106 h-1(2); AmOase, 13.4 (1) or 9.4 × 106 h-1 (2); COase, 2.0 (1) or 1.9 × 103 h-1 (2)]. They exhibit higher levels of AOase activity as indicated by their kcat values compared to the AOase enzyme. The kcat values for COase activity in buffer solution [5.93 (1) or 2.95 × 105 h-1 (2)] are one order lower than those of the enzymes. This is because of the labile nature of the coordinated donor, the flexibility of the ligand, the simplicity of the catalyst-substrate interaction, and the positive CuII/I redox potential. Interestingly, more efficient catalysis is promoted by 1 and 2 concerning that of other mono- and dicopper(II) complexes.

Sediment, as the destination of marine pollutants, often bears much more serious petroleum pollution than water. Biochar is increasingly utilized for remediating organic pollutant-laden sediments, yet its long-term impacts on oil-contaminated sediment remain poorly understood. In this study, simulation experiments adding 2.5 wt% biochars (corn straw and wood chips biochar at different pyrolysis temperatures) were conducted. The effects on petroleum hydrocarbon attenuation, enzyme activities, and microbial community structure were systematically investigated. Results showed enhanced degradation of long-chain alkanes in certain biochar-treated groups. Biochar species and PAH characteristics together lead to the PAHs\' attenuation, with low-temperature corn straw biochar facilitating the degradation of phenanthrene, fluorene, and chrysene. Initially, biochars reduced polyphenol oxidase activity but increased urease and dehydrogenase activities. However, there was a noticeable rise in polyphenol oxidase activity for a long time. Biochars influenced bacterial community succession and abundance, likely due to nutrient release stimulating microbial activity. The structural equations model (SEM) reveals that DON affected the enzyme activity by changing the microbial community and thus regulated the degradation of PAHs. These findings shed light on biochar\'s role in bacterial communities and petroleum hydrocarbon degradation over extended periods, potentially enhancing biochar-based remediation for petroleum-contaminated sediments.

BACKGROUND: Accurate and quick judgement of the food quality can protect the legitimate rights of consumers. Currently, nanozymes are widely employed in the rapid detection of food due to their stability and economy. The contents of bisphenol A and antioxidant can be used to measure the quality of beverages. However, due to the complexity of the actual samples, it is still challenging to achieve the sensitive detection of both at the same time. The development of nanozyme with high enzyme activity is essential for sensitive detection of targets in complex foods.
RESULTS: In this work, a novel nanomaterial (ZrTGA) was synthesized based on thioglycolic acid-modified Metal-Organic Framework (MOF-818). The interaction between Cu-S bonds and increase in the proportion of Cu1+ resulted in ZrTGA exhibiting higher peroxidase-like and polyphenol oxidase-like activities. These enzyme activities were 317 % and 200 % of the original values, respectively. With high enzyme activity can sensitively detect two important indicators of bisphenol A and antioxidants in beverages. The increased enzyme activity of ZrTGA enabled the content of both substances to be detected by smartphone extraction of RGB. Finally, through the output of the \'\'0″ and \'\'1″ signals of the logic gates, it is possible to quickly determine the level of the two substances and thus directly assess the quality of the beverages.
CONCLUSIONS: The modification of nanozyme enables the detection of substances at low concentrations based on enhancing dual-enzyme activity. The combination of mobile phone photography and logic gate technology enables the continuous detection of two important indicators in beverages, overcoming the limitations of traditional large-scale instruments. It also provides an alternative strategy for food quality detection.

Apple (Malus domestica Borkh.) is among the most widely planted and economically valuable horticultural crops globally. Over time, the apple fruit\'s cut surface undergoes browning, and the degree of browning varies among different apple varieties. Browning not only affects the appearance of fruits but also adversely affects their taste and flavor. In the present study, we observed browning in different apple varieties over time and analyzed the expression of genes in the polyphenol oxidase gene family. The results indicated a strong correlation between the browning degree of the fruit and the relative expression of the polyphenol oxidase gene MdPPO2. With the MdPPO2 promoter as bait, the basic leucine zipper (bZIP) transcription factor MdbZIP44 was identified using the yeast single-hybrid screening method. Further investigation revealed that the overexpression of MdbZIP44 in \'Orin\' callus could enhance the expression of MdPPO2 and promote browning of the callus. However, knocking out MdbZIP44 resulted in a callus with no apparent browning phenotype. In addition, our results confirmed the interaction between MdbZIP44 and MdbZIP11. In conclusion, the results indicated that MdbZIP44 can induce apple fruit browning by activating the MdPPO2 promoter. The results provide a theoretical basis for further clarifying the browning mechanism of apple fruit.

This study explores the impact of juglone on cucumber (Cucumis sativus cv. Beith Alpha), scrutinizing its effects on seed germination, growth, and the polyphenol oxidase (PPO) enzyme\'s activity and gene expression. Employing concentrations ranging from 0.01 to 0.5 mM, we found juglone\'s effects to be concentration-dependent. At lower concentrations (0.01 and 0.1 mM), juglone promoted root and shoot growth along with germination, whereas higher concentrations (0.25 and 0.5 mM) exerted inhibitory effects, delineating a threshold for its allelopathic influence. Notably, PPO activity surged, especially at 0.5 mM in roots, hinting at oxidative stress involvement. Real-time PCR unveiled that juglone modulates PPO gene expression in cotyledons, peaking at 0.1 mM and diminishing at elevated levels. Correlation analyses elucidated a positive link between juglone-induced root growth and cotyledon PPO gene expression but a negative correlation with heightened root enzyme activity. Additionally, germination percentage inversely correlated with root PPO activity, while PPO activities positively associated with dopa and catechol substrates in both roots and cotyledons. Molecular docking studies revealed juglone\'s selective interactions with PPO\'s B chain, suggesting regulatory impacts. Protein interaction assessments highlighted juglone\'s influence on amino acid metabolism, and molecular dynamics indicated juglone\'s stronger, more stable binding to PPO, inferring potential alterations in enzyme function and stability. Conclusively, our findings elucidate juglone\'s dose-dependent physiological and biochemical shifts in cucumber plants, offering insights into its role in plant growth, stress response, and metabolic modulation.

Insect respiration has long been thought to be solely dependent on an elaborate tracheal system without assistance from the circulatory system or immune cells1,2. Here we describe that Drosophila crystal cells-myeloid-like immune cells called haemocytes-control respiration by oxygenating Prophenoloxidase 2 (PPO2) proteins. Crystal cells direct the movement of haemocytes between the trachea of the larval body wall and the circulation to collect oxygen. Aided by copper and a neutral pH, oxygen is trapped in the crystalline structures of PPO2 in crystal cells. Conversely, PPO2 crystals can be dissolved when carbonic anhydrase lowers the intracellular pH and then reassembled into crystals in cellulo by adhering to the trachea. Physiologically, larvae lacking crystal cells or PPO2, or those expressing a copper-binding mutant of PPO2, display hypoxic responses under normoxic conditions and are susceptible to hypoxia. These hypoxic phenotypes can be rescued by hyperoxia, expression of arthropod haemocyanin or prevention of larval burrowing activity to expose their respiratory organs. Thus, we propose that insect immune cells collaborate with the tracheal system to reserve and transport oxygen through the phase transition of PPO2 crystals, facilitating internal oxygen homeostasis in a process that is comparable to vertebrate respiration.

This study was aimed to evaluate the potential of high-humidity hot air impingement cooking (HHAIC) on Penaeus vannamei, focusing on its drying characteristics, microstructure, water distribution, enzyme activity, astaxanthin content, antioxidant capacity, color, and Maillard reaction. Results demonstrated that a 3 min HHAIC significantly improved the shrimp\'s color and optimized astaxanthin content with a notable increase in scavenging capacity based on an in-vitro as antioxidation activity evaluation. Compared to the untreated samples, HHAIC could significantly inactivate polyphenol oxidase by 95.76%. Also, it suppressed the Maillard reaction by decreasing 5-hydroxymethylfurfural content and shortened the drying time by 40%. In addition, the low-field nuclear magnetic resonance and microstructure analysis showed alterations in the shrimp muscle fiber structure and water distribution. This study indicated that HHAIC could elevate quality, enhance appearance, and reduce the processing time of dried shrimp, presenting valuable implications for industry progress.

The present work evaluated kiwi juice addition alongside pasteurization (at 85 °C for 5 min) or microwave treatment (for 3 min) on the quality improvement of sugarcane juice. The juice was treated in the presence of kiwi juice (0-8%), and its physicochemical properties and microbial load were compared with raw juice. The study also highlighted the key enzymes causing sugarcane juice discoloration, peroxidase (POD) and polyphenol oxidase (PPO), by quantifying kiwi juice constituents using GC-MS and monitoring their effects by molecular docking. Kiwi addition considerably raised (p < 0.05) acidity, ascorbic acid (54.28%), and phenolic compounds (32%), and decreased the POD and PPO activity of raw cane juice. Pasteurization in the presence of kiwi, rather than microwave treatment, has significantly (p < 0.05) increased the phenolic compounds and reduced POD and PPO activities until barley was detected. Molecular docking revealed that heptacosane, oleic acid, and melezitose are the primary kiwi components responsible for enzyme inactivation.