Genome-Wide Investigation of Class III Peroxidase Genes in Brassica napus Reveals Their Responsiveness to Abiotic Stresses.

Brassica napus (B. napus) is susceptible to multiple abiotic stresses that can affect plant growth and development, ultimately reducing crop yields. In the past, many genes that provide tolerance to abiotic stresses have been identified and characterized. Peroxidase (POD) proteins, members of the oxidoreductase enzyme family, play a critical role in protecting plants against abiotic stresses. This study demonstrated a comprehensive investigation of the POD gene family in B. napus. As a result, a total of 109 POD genes were identified across the 19 chromosomes and classified into five distinct subgroups. Further, 44 duplicate events were identified; of these, two gene pairs were tandem and 42 were segmental. Synteny analysis revealed that segmental duplication was more prominent than tandem duplication among POD genes. Expression pattern analysis based on the RNA-seq data of B. napus indicated that BnPOD genes were expressed differently in various tissues; most of them were expressed in roots rather than in other tissues. To validate these findings, we performed RT-qPCR analysis on ten genes; these genes showed various expression levels under abiotic stresses. Our findings not only furnish valuable insights into the evolutionary dynamics of the BnPOD gene family but also serve as a foundation for subsequent investigations into the functional roles of POD genes in B. napus.

Quantum chemistry calculation-aided discovery of potent small-molecule mimics of glutathione peroxidases for the treatment of cisplatin-induced hearing loss.

Hearing loss (HL) is a health burden that seriously affects the quality of life of cancer patients receiving platinum-based chemotherapy, and few FDA-approved treatment specifically targets this condition. The main mechanisms that contribute to cisplatin-induced hearing loss are oxidative stress and subsequent cell death, including ferroptosis revealed by us as a new mechanism recently. In this study, we employed the frontier molecular orbital (FMO) theory approach as a convenient prediction method for the glutathione peroxidase (GPx)-like activity of isoselenazolones and discovered new isoselenazolones with great GPx-like activity. Notably, compound 19 exhibited significant protective effects against cisplatin-induced hair cell (HC) damage in vitro and in vivo and effectively reverses cisplatin-induced hearing loss through oral administration. Further investigations revealed that this compound effectively alleviated hair cell oxidative stress, apoptosis and ferroptosis. This research highlights the potential of GPx mimics as a therapeutic strategy against cisplatin-induced hearing loss. The application of quantum chemistry (QC) calculations in the study of GPx mimics sheds light on the development of new, innovative treatments for hearing loss.

Actinobacterial peroxidase-mediated biodeterioration of hazardous explosive, 2, 4, 6, trinitrophenol by in silico and in vitro approaches.

Explosives are perilous and noxious to aquatic biota disrupting their endocrinal systems. Supplementarily, they exhibit carcinogenic, teratogenic and mutagenic effects on humans and animals. Henceforth, the current study has been targeted to biotransform the explosive, 2, 4, 6 trinitrophenol (TNP) by wetland peroxidase from Streptomyces coelicolor. A total peroxidase yield of 20,779 mg/l with 51.6 folds of purification was observed. In silico molecular docking cum in vitro appraisals were accomplished to assess binding energy and interacting binding site residues of peroxidase and TNP complex. TNP required a minimal binding energy of-6.91 kJ/mol and was subjected to biodeterioration (89.73%) by peroxidase in purified form, with 45 kDa and a similarity score of 34 by MASCOT protein analysis. Moreover, the peroxidase activity was confirmed with Zymogram analysis. Characterization of peroxidase revealed that optimum values of pH and temperature as 6 and 40 °C, respectively, with their corresponding stability varying from 3.5 to 7. Interestingly, the kinetic parameters such as Km and Vmax on 2,2'-azino-bis 3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and H2O2 were 19.27 µm and 0.41 µm/min; 21.4 µm and 0.1 µm/min, respectively. Among the diverse substrates, chemicals and trace elements, ABTS (40 mM), citric acid (5 mM) and Fe2+ (5 mM) displayed the highest peroxidase activity. Computational docking and in vitro results were corroborative and UV-Vis spectroscopy, HPLC, FTIR and GC-MS indicated the presence of simple metabolites of TNP such as nitrophenols and benzoquinone, showcasing the efficacy of S. coelicolor peroxidase to biotransform TNP. Henceforth, the current study offers a promising channel for biological treatment of explosive munitions, establishing a sustainable green earth.

Cardiolipin Membranes Promote Cytochrome c Transformation of Polycyclic Aromatic Hydrocarbons and Their In Vivo Metabolites.

The catalytic properties of cytochrome c (Cc) have captured great interest in respect to mitochondrial physiology and apoptosis, and hold potential for novel enzymatic bioremediation systems. Nevertheless, its contribution to the metabolism of environmental toxicants remains unstudied. Human exposure to polycyclic aromatic hydrocarbons (PAHs) has been associated with impactful diseases, and animal models have unveiled concerning signs of PAHs' toxicity to mitochondria. In this work, a series of eight PAHs with ionization potentials between 7.2 and 8.1 eV were used to challenge the catalytic ability of Cc and to evaluate the effect of vesicles containing cardiolipin mimicking mitochondrial membranes activating the peroxidase activity of Cc. With moderate levels of H2O2 and at pH 7.0, Cc catalyzed the oxidation of toxic PAHs, such as benzo[a]pyrene, anthracene, and benzo[a]anthracene, and the cardiolipin-containing membranes clearly increased the PAH conversions. Our results also demonstrate for the first time that Cc and Cc-cardiolipin complexes efficiently transformed the PAH metabolites 2-hydroxynaphthalene and 1-hydroxypyrene. In comparison to horseradish peroxidase, Cc was shown to reach more potent oxidizing states and react with PAHs with ionization potentials up to 7.70 eV, including pyrene and acenaphthene. Spectral assays indicated that anthracene binds to Cc, and docking simulations proposed possible binding sites positioning anthracene for oxidation. The results give support to the participation of Cc in the metabolism of PAHs, especially in mitochondria, and encourage further investigation of the molecular interaction between PAHs and Cc.

Under explored roles of microbial ligninolytic enzymes in aerobic polychlorinated biphenyl transformation.

Polychlorinated biphenyls (PCBs) are persistent organic pollutants in the environment that are responsible for many adverse health effects. Bioremediation appears to be a healthy and cost-effective alternative for remediating PCB-contaminated environments. While some microbial species have been observed to be capable of transforming PCBs, only two different microbial pathways (rdh and bph pathways) have been described to be involved in PCB transformations. Ligninolytic enzymes have been observed or are under suspicion in some microbial PCB transformations. However, the role of these promising PCB-transforming enzymes, which are produced by fungi and some aerobic bacteria, is still unclear. The present review describes their role by identifying microbial PCB-transforming species and their reported ligninolytic enzymes whether proven or suspected to be involved in PCB transformations. There are several lines of evidence that ligninolytic enzymes are responsible for PCB transformations such as (1) the ability of purified laccases from Myceliophthora thermophila, Pycnoporus cinnabarinus, Trametes versicolor, Cladosporium sp, and Coprinus cumatus to transform hydroxy-PCBs; (2) the increased production of laccases and peroxidases by many fungi in the presence of PCBs; and (3) the enhanced PCB transformation by Pseudomonas stutzeri and Sinorhizobium meliloti NM after the addition of ligninolytic enzyme enhancers. However, if the involvement of ligninolytic enzymes in PCB transformation is clearly demonstrated in some fungal species, it does not seem to be implicated in all microbial species suggesting other still unknown metabolic pathways involved in PCB transformation and different from the bph and rdh pathways. Therefore, PCB transformation may involve several metabolic pathways, some involving ligninolytic enzymes, bph or rdh genes, and some still unknown, depending on the microbial species. In addition, current knowledge does not fully clarify the role of ligninolytic enzymes in PCB oxidation and dechlorination. Therefore, further studies focusing on purified ligninolytic enzymes are needed to clearly elucidate their role in PCB transformation.

Genome sequencing of Porostereum spadiceum to study the degradation of levofloxacin.

Despite various plans to rationalize antibiotic use, antibiotic resistance in environmental bacteria is increasing due to the accumulation of antibiotic residues in the environment. This study aimed to test the ability of basidiomycete fungal strains to biotransform the antibiotic levofloxacin, a widely-used third-generation broad-spectrum fluoroquinolone, and to propose enzyme targets potentially involved in this biotransformation. The biotransformation process was performed using fungal strains. Levofloxacin biotransformation reached 100% after 9 days of culture with Porostereum spadiceum BS34. Using genomics and proteomics analyses coupled with activity tests, we showed that P. spadiceum produces several heme-peroxidases together with H2O2-producing enzymes that could be involved in the antibiotic biotransformation process. Using UV and high-resolution mass spectrometry, we were able to detect five levofloxacin degradation products. Their putative identity based on their MS2 fragmentation patterns led to the conclusion that the piperazine moiety was the main target of oxidative modification of levofloxacin by P. spadiceum, leading to a decrease in antibiotic activity.

Heterologous expression of Arabidopsis laccase2, laccase4 and peroxidase52 driven under developing xylem specific promoter DX15 improves saccharification in populus.

BACKGROUND: Secondary cell wall holds considerable potential as it has gained immense momentum to replace the lignocellulosic feedstock into fuels. Lignin one of the components of secondary cell wall tightly holds the polysaccharides thereby enhancing the recalcitrance and complexity in the biomass. Laccases (LAC) and peroxidases (PRX) are the major phenyl-oxidases playing key functions during the polymerization of monolignols into lignin. Yet, the functions of laccase and peroxidases gene families remained largely unknown. Hence, the objective of this conducted study is to understand the role of specific LAC and PRX in Populus wood formation and to further investigate how the altered Lac and Prx expression affects biomass recalcitrance and plant growth. This study of heterologous expression of Arabidopsis Lac and Prx genes was conducted in poplar to avoid any otherwise occurring co-suppression mechanism during the homologous overexpression of highly expressed native genes. In the pursuit of optimizing lignocellulosic biomass for biofuel production, the present study focuses on harnessing the enzymatic potential of Arabidopsis thaliana Laccase2, Laccase4, and Peroxidase52 through heterologous expression. RESULTS: We overexpressed selected Arabidopsis laccase2 (AtLac2), laccase4 (AtLac4), and peroxidase52 (AtPrx52) genes, based on their high transcript expression respective to the differentiating xylem tissues in the stem, in hybrid poplar (cv. 717) expressed under the developing xylem tissue-specific promoter, DX15 characterized the transgenic populus for the investigation of growth phenotypes and recalcitrance efficiency. Bioinformatics analyses conducted on AtLac2 and AtLac4 and AtPrx52, revealed the evolutionary relationship between the laccase gene and peroxidase gene homologs, respectively. Transgenic poplar plant lines overexpressing the AtLac2 gene (AtLac2-OE) showed an increase in plant height without a change in biomass yield as compared to the controls; whereas, AtLac4-OE and AtPrx52-OE transgenic lines did not show any such observable growth phenotypes compared to their respective controls. The changes in the levels of lignin content and S/G ratios in the transgenic poplar resulted in a significant increase in the saccharification efficiency as compared to the control plants. CONCLUSIONS: Overall, saccharification efficiency was increased by 35-50%, 21-42%, and 8-39% in AtLac2-OE, AtLac4-OE, and AtPrx52-OE transgenic poplar lines, respectively, as compared to their controls. Moreover, the bioengineered plants maintained normal growth and development, underscoring the feasibility of this approach for biomass improvement without compromising overall plant fitness. This study also sheds light on the potential of exploiting regulatory elements of DX15 to drive targeted expression of lignin-modifying enzymes, thereby providing a promising avenue for tailoring biomass for improved biofuel production. These findings contribute to the growing body of knowledge in synthetic biology and plant biotechnology, offering a sustainable solution to address the challenges associated with lignocellulosic biomass recalcitrance.

Cold priming on pathogen susceptibility in the Arabidopsis eds1 mutant background requires a functional stromal Ascorbate Peroxidase.

24 h cold exposure (4°C) is sufficient to reduce pathogen susceptibility in Arabidopsis thaliana against the virulent Pseudomonas syringae pv. tomato (Pst) strain even when the infection occurs five days later. This priming effect is independent of the immune regulator Enhanced Disease Susceptibility 1 (EDS1) and can be observed in the immune-compromised eds1-2 null mutant. In contrast, cold priming-reduced Pst susceptibility is strongly impaired in knock-out lines of the stromal and thylakoid ascorbate peroxidases (sAPX/tAPX) highlighting their relevance for abiotic stress-related increased immune resilience. Here, we extended our analysis by generating an eds1 sapx double mutant. eds1 sapx showed eds1-like resistance and susceptibility phenotypes against Pst strains containing the effectors avrRPM1 and avrRPS4. In comparison to eds1-2, susceptibility against the wildtype Pst strain was constitutively enhanced in eds1 sapx. Although a prior cold priming exposure resulted in reduced Pst titers in eds1-2, it did not alter Pst resistance in eds1 sapx. This demonstrates that the genetic sAPX requirement for cold priming of basal plant immunity applies also to an eds1 null mutant background.

Spectroelectrochemistry for determination of the redox potential in heme enzymes: Dye-decolorizing peroxidases.

Dye-decolorizing peroxidases (DyPs) are heme-containing enzymes that are structurally unrelated to other peroxidases. Some DyPs show high potential for applications in biotechnology, which critically depends on the stability and redox potential (E°') of the enzyme. Here we provide a comparative analysis of UV-Vis- and surface-enhanced resonance Raman-based spectroelectrochemical methods for determination of the E°' of DyPs from two different organisms, and their variants generated targeting E°' upshift. We show that substituting the highly conserved Arginine in the distal side of the heme pocket by hydrophobic amino acid residues impacts the heme architecture and redox potential of DyPs from the two organisms in a very distinct manner. We demonstrate the advantages and drawbacks of the used spectroelectrochemical approaches, which is relevant for other heme proteins that contain multiple heme centers or spin populations.

Biochemical, Biophysical, and Structural Analysis of an Unusual DyP from the Extremophile Deinococcus radiodurans.

Dye-decolorizing peroxidases (DyPs) are heme proteins with distinct structural properties and substrate specificities compared to classical peroxidases. Here, we demonstrate that DyP from the extremely radiation-resistant bacterium Deinococcus radiodurans is, like some other homologues, inactive at physiological pH. Resonance Raman (RR) spectroscopy confirms that the heme is in a six-coordinated-low-spin (6cLS) state at pH 7.5 and is thus unable to bind hydrogen peroxide. At pH 4.0, the RR spectra of the enzyme reveal the co-existence of high-spin and low-spin heme states, which corroborates catalytic activity towards H2O2 detected at lower pH. A sequence alignment with other DyPs reveals that DrDyP possesses a Methionine residue in position five in the highly conserved GXXDG motif. To analyze whether the presence of the Methionine is responsible for the lack of activity at high pH, this residue is substituted with a Glycine. UV-vis and RR spectroscopies reveal that the resulting DrDyPM190G is also in a 6cLS spin state at pH 7.5, and thus the Methionine does not affect the activity of the protein. The crystal structures of DrDyP and DrDyPM190G, determined to 2.20 and 1.53 Å resolution, respectively, nevertheless reveal interesting insights. The high-resolution structure of DrDyPM190G, obtained at pH 8.5, shows that one hydroxyl group and one water molecule are within hydrogen bonding distance to the heme and the catalytic Asparagine and Arginine. This strong ligand most likely prevents the binding of the H2O2 substrate, reinforcing questions about physiological substrates of this and other DyPs, and about the possible events that can trigger the removal of the hydroxyl group conferring catalytic activity to DrDyP.

The nitrate transporter-sensor MtNPF6.8 regulates the branched chain amino acid/pantothenate metabolic pathway in barrel medic (Medicago truncatula Gaertn.) root tip.

Nitrogen is the most limiting nutrient for plants, and it is preferentially absorbed in the form of nitrate by roots, which adapt to nitrate fluctuations by remodelling their architecture. Although core mechanisms of the response to nitrate availability are relatively well-known, signalling events controlling root growth and architecture have not all been identified, in particular in Legumes. However, the developmental effect of nitrate in Legumes is critical since external nitrate not only regulates root architecture but also N2-fixing nodule development. We have previously shown that in barrel medic (Medicago truncatula), the nitrate transporter MtNPF6.8 is required for nitrate sensitivity in root tip. However, uncertainty remains as to whether nitrogen metabolism itself is involved in the MtNPF6.8-mediated response. Here, we examine the metabolic effects of MtNPF6.8-dependent nitrate signalling using metabolomics and proteomics in WT and mtnpf6.8 root tips in presence or absence of nitrate. We found a reorchestration of metabolism due to the mutation, in favour of the branched chain amino acids/pantothenate metabolic pathway, and lipid catabolism via glyoxylate. That is, the mtnpf6.8 mutation was likely associated with a specific rerouting of acetyl-CoA production (glyoxylic cycle) and utilisation (pantothenate and branched chain amino acid synthesis). In agreement with our previous findings, class III peroxidases were confirmed as the main protein class responsive to nitrate, although in an MtNPF6.8-independent fashion. Our data rather suggest the involvement of other pathways within mtnpf6.8 root tips, such as Ca2+ signalling or cell wall methylation.

Spiky Artificial Peroxidases with V-O-Fe Pair Sites for Combating Antibiotic-Resistant Pathogens.

With the sharp rise of antibiotic-resistant pathogens worldwide, it is of enormous importance to create new strategies for combating pathogenic bacteria. Here, we create an iron oxide-based spiky artificial peroxidase (POD) with V-O-Fe pair sites (V-Fe2 O3 ) for combating methicillin-resistant Staphylococcus aureus (MRSA). The experimental studies and theoretical calculations demonstrate that the V-Fe2 O3 can achieve the localized "capture and killing" bifunction from the spiky morphology and massive reactive oxygen species (ROS) production. The V-Fe2 O3 can reach nearly 100 % bacterial inhibition over a long period by efficiently oxidizing the lipid membrane. Our wound disinfection results identify that the V-Fe2 O3 can not only efficiently eliminate MRSA and their biofilm but also accelerate wound recovery without causing noticeable inflammation and toxicity. This work offers essential insights into the critical roles of V-O-Fe pair sites and localized "capture and killing" in biocatalytic disinfection and provides a promising pathway for the de novo design of efficient artificial peroxidases.

Fast Antioxidation Kinetics of Glutathione Intracellularly Monitored by a Dual-Wire Nanosensor.

The glutathione (GSH) system is one of the most powerful intracellular antioxidant systems for the elimination of reactive oxygen species (ROS) and maintaining cellular redox homeostasis. However, the rapid kinetics information (at the millisecond to the second level) during the dynamic antioxidation process of the GSH system remains unclear. As such, we specifically developed a novel dual-wire nanosensor (DWNS) that can selectively and synchronously measure the levels of GSH and ROS with high temporal resolution, and applied it to monitor the transient ROS generation as well as the rapid antioxidation process of the GSH system in individual cancer cells. These measurements revealed that the glutathione peroxidase (GPx) in the GSH system is rapidly initiated against ROS burst in a sub-second time scale, but the elimination process is short-lived, ending after a few seconds, while some ROS are still present in the cells. This study is expected to open new perspectives for understanding the GSH antioxidant system and studying some redox imbalance-related physiological.

Lentinula edodes lignocellulolases and lipases produced in Macaúba residue and use of the enzymatic extract in the degradation of textile dyes.

Agro-industrial residue and textile effluents have caused environmental damage to soil and water bodies. The production of fungal enzymes using agro-industrial residues and the use of these enzymes in the degradation of textile dyes can be a viable alternative to reduce these environmental damages. Lentinula edodes is a white rot fungus with high nutritional value that produces edible mushrooms and enzymes of commercial interest. Thus, the objectives of this study were to produce, purify, and biochemically characterize the lignocellulolytic enzymes and lipases produced for L. edodes in Macaúba coconut and to evaluate their potential for the degradation of textile dyes. The L. edodes UFV 73 had maximum enzymatic activity at 37 days of incubation. After the purification steps, the laccase, manganese peroxidase (MnP), cellulase, and, xylanase yields were 489.01, 264.2, 105.02, and 9.5%. The optimum temperature of cellulase activity did not change from 4 to 60 °C. The MnP, laccase, and lipase had activity directly proportional to the increase in temperature, while the cellulase and xylanase activity did not change. The optimum pH varied among analyzed enzymes. All the enzymes analyzed are according to Michaelis-Menten kinetics. The lignocellulolytic enzymes were stable up to 8 h of incubation and lipase had a reduction of activity after one hour. The discoloration rate of indigo dye by partially purified enzymatic extract (PPPE) was 40%, which shows its potential for degradation of dyes from textile industries.

The ferroptosis landscape in acute myeloid leukemia.

Ferroptosis induction through the suppression of glutathione peroxidase 4 (GPX4) and apoptosis-inducing factor mitochondria-associated 2 (AIFM2) has proven to be an effective approach in eliminating chemotherapy-resistant cells of various types. However, a comprehensive understanding of the roles of GPX4 and AIFM2 in acute myeloid leukemia (AML) has not yet been achieved. Using cBioPortal, DepMap, GEPIA, Metascape, and ONCOMINE, we compared the transcriptional expression, survival data, gene mutation, methylation, and network analyses of GPX4- and AIFM2-associated signaling pathways in AML. The results revealed that high expression levels of GPX4 and AIFM2 are associated with an adverse prognosis for AML patients. Overexpression of AIFM2 correlated with elevated mutation frequencies in NPM1 and DNMT3A. GPX4 upregulation modulated the following pathways: GO:0045333, cellular respiration; R-HSA-5389840, mitochondrial translation elongation; GO:0009060, aerobic respiration; R-HSA-9609507, protein localization; and R-HSA-8953854, metabolism of RNA. On the other hand, the overexpression of AIFM2 influenced the following processes: GO:0048704, embryonic skeletal system morphogenesis; GO:0021546, rhombomere development; GO:0009954, proximal/distal pattern formation; and GO:0048732, gland development. This study identifies the high expression of GPX4 and AIFM2 as novel biomarkers predicting a poor prognosis for AML patients. Furthermore, ferroptosis induction may improve the stratified treatment of AML.

Role of Tyrosine Nitrosylation in Stress-Induced Major Depressive Disorder: Mechanisms and Implications.

Major depressive disorder (MDD) has a lifetime prevalence of approximately 10% and is one of the most common diseases worldwide. Although many pathogenetic mechanisms of MDD have been proposed, molecular details and a unifying hypothesis of the pathogenesis of MDD remain to be defined. Here, we investigated whether tyrosine nitrosylation, which is caused by reaction of the C-atom 3 of the tyrosine phenol ring with peroxynitrate (ONOO-), plays a role in experimental MDD, because tyrosine nitrosylation may affect many cell functions altered in MDD. To this end, we induced stress through glucocorticoid application or chronic environmental unpredictable stress and determined tyrosine nitrosylation in the hippocampus through immuno-staining and ELISA. The role of catalases and peroxidases for tyrosine nitrosylation was measured using enzyme assays. We show that glucocorticoid- and chronic unpredictable environmental stress induced tyrosine nitrosylation in the hippocampus. Long-term treatment of stressed mice with the classical antidepressants amitriptyline or fluoxetine prevented tyrosine nitrosylation. Tyrosine nitrosylation was also prevented through i.v. application of anti-ceramide antibodies or recombinant ceramidase to neutralize or degrade, respectively, blood plasma ceramide that has been recently shown to induce experimental MDD. Finally, the application of phosphatidic acid, previously shown to be reduced in the hippocampus upon stress, also reverted stress-induced tyrosine nitrosylation. The inhibition of tyrosine nitrosylation by interfering with the formation of NO radicals at least partly restored normal behavior in stressed mice. These data suggest that tyrosine nitrosylation might contribute to the pathogenesis of MDD and targeting this process might contribute to the treatment of MDD.

The role of peroxidasin in solid cancer progression.

Peroxidasin is a heme-containing peroxidase enzyme that plays a vital role in the cross-linking of collagen IV molecules in basement membranes. Collagen IV cross-links are essential for providing structure and mechanical stability throughout tissue development, homeostasis, and wound healing. During cancer progression, the basement membrane is degraded, and proteins typically found in the basement membrane, including peroxidasin and collagen IV, can be found spread throughout the tumour microenvironment where they interact with cancer cells and alter cell behaviour. Whilst peroxidasin is reported to be up-regulated in a number of different cancers, the role that it plays in disease progression and metastasis has only recently begun to be studied. This review highlights the current literature exploring the known roles of peroxidasin in normal tissues and cancer progression, regulators of peroxidasin expression, and the reported relationships between peroxidasin expression and patient outcome in cancer.

Elucidating the role of media nitrogen in augmenting the production of lignin-depolymerizing enzymes by white-rot fungi.

Indigenous white-rot fungal isolates Schizophyllum commune, Phanerochaete chrysosporium, Ganoderma racenaceum, and Lentinus squarrosulus, demonstrating the ability to depolymerize lignin of the crop residues, were studied for their potential to produce ligninolytic enzymes using modified production media under conditions of limiting and excess nitrogen for higher enzymatic expressions. Secretome-rich media on the investigation confirmed the successful production of lignin-depolymerizing enzymes, viz. laccase, lignin peroxidase, manganese peroxidase, and versatile peroxidase. Production of laccases and peroxidases was statistically significant in nitrogen-limiting media with and without the substrate, across all white-rot fungal cultures at 95% confidence interval. Nitrogen-limiting media with the substrate on analysis extracellularly expressed 99.27 U of laccase and 68.48 U of manganese peroxidase in Schizophyllum commune, while 195.14 U of lignin peroxidase was produced by Phanerochaete chrysosporium. Lentinus squarrosulus expressed 455.34 U of laccase and 357.13 U of versatile peroxidase with 250.09 U of laccase and 206.95 U of manganese peroxidase produced by Ganoderma racenaceum for every milliliter of the media used. Nitrogen-limiting media triggered the production of laccase during the initial stages of growth while the expression of peroxidases was predominant at a later stage. Also, this media evinced increased enzymatic yields with low biomass content compared to nitrogen-excess conditions. The extant study confirmed the positive influence of nitrogen-limiting media in the efficient production of ligninolytic enzymes and their suggestive degradation potential for environmental pollutants, making these enzymes a safe, clean alternative to the use of chemicals and the media to be effective for large-scale production of ligninolytic enzymes. IMPORTANCE Lignin on account of its high abundance, complex polymeric structure, and biochemical properties is identified as a promising candidate in renewable energy and bioproduct manufacturing. However, depolymerization of lignin remains a major challenge in lignin utilization, entailing the employment of harsh treatments representing not only an environmental concern but also a waste of economic potential. Developing an alternative green technology to minimize this impact is imperative. Methods using enzymes to depolymerize lignin are the focus of recent studies. Current research work emphasized the efficient expression of the major lignin-depolymerizing enzymes: laccases, lignin peroxidases, manganese peroxidases, and versatile peroxidases from native isolates of white-rot fungus for several biotechnological applications as well as treatment of crop residues for use as ruminant feed in improving productivity. The importance of nitrogen in augmenting the expression of lignin-depolymerizing enzymes and providing a media recipe for the cost-effective production of ligninolytic enzymes is highlighted.

Exoproteomic Study and Transcriptional Responses of Laccase and Ligninolytic Peroxidase Genes of White-Rot Fungus Trametes hirsuta LE-BIN 072 Grown in the Presence of Monolignol-Related Phenolic Compounds.

Being an abundant renewable source of aromatic compounds, lignin is an important component of future bio-based economy. Currently, biotechnological processing of lignin through low molecular weight compounds is one of the conceptually promising ways for its valorization. To obtain lignin fragments suitable for further inclusion into microbial metabolism, it is proposed to use a ligninolytic system of white-rot fungi, which mainly comprises laccases and peroxidases. However, laccase and peroxidase genes are almost always represented by many non-allelic copies that form multigene families within the genome of white-rot fungi, and the contributions of exact family members to the overall process of lignin degradation has not yet been determined. In this article, the response of the Trametes hirsuta LE-BIN 072 ligninolytic system to the presence of various monolignol-related phenolic compounds (veratryl alcohol, p-coumaric acid, vanillic acid, and syringic acid) in culture media was monitored at the level of gene transcription and protein secretion. By showing which isozymes contribute to the overall functioning of the ligninolytic system of the T. hirsuta LE-BIN 072, the data obtained in this study will greatly contribute to the possible application of this fungus and its ligninolytic enzymes in lignin depolymerization processes.

Oxidoreductase enzymes: Characteristics, applications, and challenges as a biocatalyst.

Oxidoreductases are enzymes with distinctive characteristics that favor their use in different areas, such as agriculture, environmental management, medicine, and analytical chemistry. Among these enzymes, oxidases, dehydrogenases, peroxidases, and oxygenases are very interesting. Because their substrate diversity, they can be used in different biocatalytic processes by homogeneous and heterogeneous catalysis. Immobilization of these enzymes has favored their use in the solution of different biotechnological problems, with a notable increase in the study and optimization of this technology in the last years. In this review, the main structural and catalytical features of oxidoreductases, their substrate specificity, immobilization, and usage in biocatalytic processes, such as bioconversion, bioremediation, and biosensors obtainment, are presented.