Myrothecium Verrucaria Research Articles

Direct electron transfer of bilirubin oxidase at a carbon flow-through electrode

The kinetics and isotherms of adsorption of Myrothecium verrucaria bilirubin oxidase (Mv BOD) on nanoporous carbons (CNP) and carbon nanofibers (CNF) were studied by the solution depletion method. The kinetics of adsorption of Mv BOD on both carbons are very fast, reaching equilibrium within 10 min and 30 min for CNP and CNF, respectively. The adsorption isotherms reveal a strong affinity between Mv BOD and both carbons. An original flow-through device based on electrodes filled with CNP and CNF connected to an UV–vis spectrophotometer was used to correlate the dioxygen catalytic current reduction to the amount of Mv BOD adsorbed on the carbons. It was shown that although the amount of BOD adsorbed on CNP is much lower than the amount adsorbed on CNF, the currents are comparable, suggesting that the Mv BOD orientation is more favourable for direct electron transfer in the case of CNP. Chronoamperometry experiments showed that the catalytic current is stable for a few days (70 h). It was emphasized by stop and flow experiments that the current is limited by mass transport inside the column.

An efficient strategy for enhancing enzymatic saccharification with delignified fungus Myrothecium verrucaria and solid acid

In this work, corn stover was studied as a lignocellulosic material with the potential of serving as a feedstock in the field of bioenergetics. To improve the enzymatic digestibility of carbohydrates in the lignocellulosic biomass, corn stover was pretreated using Myrothecium verrucaria to deplete the lignin, combined with a solid acid pretreatment method to deplete the hemicellulose. The effects of lignin degradation conditions and solid acid concentration on cellulose conversion were investigated. The two-stage pretreatment with M. verrucaria and solid acid under optimal conditions gave 81.54% cellulose conversion yield, 214.22% higher than that of untreated corn stover. Significant lignin and hemicellulose removal rates were observed with the two-stage pretreatment. Scanning electron microscope (SEM), X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses showed major structural changes in the pretreated corn stover. This study provided an efficient strategy to enhance the enzymatic saccharification of cellulose in corn stover.

Direct Electrochemistry of Bilirubin Oxidase from Magnaporthe orizae on Covalently-Functionalized MWCNT for the Design of High-Performance Oxygen-Reducing Biocathodes.

Herein, the direct electrochemistry of bilirubin oxidase from Magnaporthe orizae (MoBOD) was studied on CNTs functionalized by electrografting several types of diazonium salts. The functionalization induces favorable or unfavorable orientation of MoBOD, the latter being compared to the well-known BOD from Myrothecium verrucaria (MvBOD). On the same nanostructured electrodes, MoBOD can surpass MvBOD in terms of both current densities and minimal overpotentials. Added to the fact that MoBOD is also highly active at the gas-diffusion electrode (GDE), these findings make MoBOD one of the MCOs with the highest catalytic activity towards the oxygen reduction reaction (ORR).

Emerging pathogens as a consequence of globalization and climate change: leafy vegetables as a case study.

In the recent years (2010–2016), leafy vegetables have been found to be hosts for many new diseases. The causal agents of these diseases had often been known on other crops, but have appeared for the first time throughout the world on several cultivated vegetable hosts such as: Lactuca sativa , Diplotaxis spp., Eruca sativa , Valerianella olitoria , Ocimum basilicum and Spinacia oleracea . This review considers pathogens such as Alternaria spp. on basil and rocket, Fusarium equiseti on lettuce, rocket and radish, and Myrothecium verrucaria and M. roridum on lamb’s lettuce, spinach and wild rocket. All these pathogens are seed-transmitted, a biological characteristic that raises the risk of worldwide dissemination. The role of climate change and globalization on the appearance of such diseases, and potential tools for their management under a climate change scenario, is discussed using leafy vegetables as a case study.

Nematicidal activity of verrucarin A and roridin A isolated from Myrothecium verrucaria against Meloidogyne incognita

The widespread use of synthetic nematicides has caused significant problems to the environment as well as human health. To address this issue, eco-friendly control measures, such as microbial nematicides, are being developed. During the screening of Myrothecium strains with nematicidal activity against the root-knot nematode (RKN) Meloidogyne incognita, we found that the acetone extract of Myrothecium sp. KACC 40321 was highly effective against hatched juveniles of M. incognita at 7 days after exposure. The fungus was identified as Meloidogyne verrucaria. Two macrocyclic trichothecenes verrucarin A and roridin A were isolated and identified as major active metabolites by bioassay-guided fractionation and instrumental analysis. When the second-stage juveniles were treated with the chemicals, no juvenile mortality was observed. However, they effectively killed juveniles from treated eggs. The hatched juvenile mortality was used to evaluate the in vitro nematicidal activity of the compounds against M. incognita. The median effective concentrations were 1.88 μg/mL for verrucarin A and 1.50 μg/mL for roridin A. Among various liquid media, commercial malt extract broth (cMEB) was found to be the best for the production of verrucarin A and roridin A, followed by potato dextrose broth. The cMEB culture filtrate effectively reduced the formation of galls and egg masses on tomato roots in a pot experiment. In addition, the culture filtrate reduced the formation of galls on the roots of melon plants and the number of RKNs in the soils under field conditions. These results suggest that M. verrucaria KACC 40321 can be used as a biocontrol agent against RKNs in various crops. To the best of our knowledge, this is the first study to report the effectiveness of verrucarin A and rorridin A against hatched juveniles of M. incognita.

Theoretical Modeling, Facile Fabrication, and Experimental Study of Optimally Bound Bilirubin Oxidase on Palladium Nanoparticles for Enhanced Oxygen Reduction Reaction

This paper presents an optimally bound bilirubin oxidase (BOD) (Myrothecium verrucaria) on palladium nanoparticles (Pd NPs) for enhanced oxygen reduction reaction (ORR). Theoretical modeling of BOD on Pd demonstrated that Pd has strong preferential binding to BOD via T1 copper (Cu) site because of its high adsorption energy. This preferential binding was accompanied by a reduction in distance between the Cu active sites and Pd which would result in an increase in electron transfer rate (kcat) and an enhancement in catalytic activity of BOD. Inspired by the computational results, a biocathode comprising carbon nanotube (CNT), Pd NPs, and BOD (CNT-Pd-BOD) was facilely fabricated using an electroless deposition method. The CNT-Pd-BOD biocathode exhibited higher catalytic activity (1.52 times) and kcat (1.71 times) when compared with CNT-BOD only biocathode. These results demonstrate Pd NPs as a suitable substrate for preferential binding with BOD to increase catalytic activity.

Pengembangan Teknologi Pengendalian Penyakit Layu Tomat (Fusarium oxysporum f. sp. lycopersici) yang Ramah Lingkungan dengan Menggunakan Mikroorganisme Saprofit

Fusarium wilt disease is a common disease for tomatoes plant which damages plant although it is intensively cultivated. Biological control by microbial antagonism is environmentally friendly compare to the use of fungicide. This research was aimed to study the capability of Bacillus subtilis, Pseudomonas fluorescens, Gliocladium fimbriatum and Trichoderma viridae that are locally specific in controll Fusarium oxysporum f.sp. lycopersici� cause tomato wilt disease. Evaluation of F.o. f.sp. lycopersici� antagonism capability was done by in vitro and in vivo.� In vitro antagonism treatment used the ouble plating treatment on Potato Dextose Agar.� In vivo antagonism treatment was done by gave antagonism agent and F.o. f.sp. lycopersici� together to the earth medium. The result of the study revealed that (1) B. subtilis, G. fimbriatum and T. viridae can pressure the growth and development �F.o. f.sp. lycopersici which cause tomato wilt disease both in vitro and in vivo, (2) In vitro the average of the prevented pathogen growth was as follow: B. subtilis (55.52%), G. fimbriatum (36.77%) and� T. viridae (35.87%), (3) In vivo treatment by the earth medium was not significantly different, and (4) In vivo the ability of prevent disease intensity was as follow : B. subtilis (62.35%), G. fimbriatum (49.95%) and� T. viridae (49.95%).

KERAGAMAN JENIS JAMUR YANG MENYERANG TANAMAN MAHONI (Swietenia Macrophylla KING.) DI KAMPUS UNIVERSITAS HASANUDDIN MAKASSAR, SULAWESI SELATAN

Many Mahogany (Swietenia macrophylla King.) is used as the main tree in the area or the forestry industry plans. If the tree is planted monoculture, the mahogany stand has become highly vulnerable to pest and diseases, because monoculture tree plantations are an abundant food source for both organisms. This study aims to determine the types of fungi that attacking and cause disease in plant parts mahogany. The result showed that there are ten species of fungi that attack mahogany. Seven of them have been identified while the other cannot be identified. Fungi are attacked or negative associations in the roots, stem, leaves and fruits of plant mahogany. The seven species of fungi are Rhizopus arrhizus Fischer; Mucor racemosus Fres; Mycgone rosea Link; Absidia corymbifera (Cohn.) Sacc and Trotter; Monilia sitophila (Mont.) Sacc; Cladosporium spharospermeum Penzig; and Myrothecium verrucaria (Orig.). Fungi that attack the roots of the tree are A. corymbifera (Cohn.) Sacc and C. spharospermeum Penzig. M. rosea Link and M. sitophila (Mont.) Sacc attacking the leaf. R. arrhizus Fischer and M. verrucaria (Orig.) attacks the stems of trees while Mucor racemosus Fres. Attacking the fruit of mahogany. Fungi that cannot be identified are a fungus that attacks the stems and leaves. Key words: Switenia macrophylla King, Fungi

Design of Experiments Approach to Provide Enhanced Glucose‐oxidising Enzyme Electrode for Membrane‐less Enzymatic Fuel Cells Operating in Human Physiological Fluids

AbstractGraphite electrodes are modified with a redox polymer, [Os(4,4′‐dimethoxy‐2,2′‐bipyridine)2(polyvinylimidazole)10Cl]+ (E°′=−0.02 V vs Ag/AgCl (3 M KCl), crosslinked with a flavin adenine dinucleotide glucose dehydrogenase and multi‐walled carbon nanotubes for electrocatalytic oxidation of glucose. The enzyme electrodes provide 52 % higher current density, 1.22±0.10 mA cm−2 in 50 mM phosphate‐buffered saline at 37 °C containing 5 mM glucose, when component amounts are optimised using a design of experiments approach compared to one‐factor‐at‐a‐time. Current densities of 0.84±0.15 mA cm−2 were achieved in the presence of oxygen for these enzyme electrodes. Further analysis of the model allowed for altering of the electrode components while maintaining similar current densities, 0.78±0.11 mA cm−2 with 34 % less enzyme. Application of the cost‐effective anodes in membrane‐less enzymatic fuel cells is demonstrated by connection to cathodes prepared by co‐immobilisation of [Os(2,2′‐bipyridine)2(polyvinylimidazole)10Cl+] redox polymer, Myrothecium verrucaria bilirubin oxidase and multi‐walled carbon nanotubes on graphite electrodes. Power densities of up to 285 μW cm−2, 146 μW cm−2 and 60 μW cm−2 are achieved in pseudo‐physiological buffer, artificial plasma and human plasma respectively, showing promise for in vivo or ex vivo power generation under these conditions.

Evaluation of Screened Lignin-degrading Fungi for the Biological Pretreatment of Corn Stover

The biological pretreatment of lignocellulosic biomass is a low-cost and eco-friendly method for facilitating enzymatic hydrolysis. In this study, strains with lignin depletion capability were screened using a high-throughput screening method. Sixty-three strains were screened out and Myrothecium verrucaria secreted three lignin-degrading enzymes simultaneously during the bio-pretreatment process. The activity levels of laccase, lignin peroxidase and manganese peroxidase were 6.61, 0.78 and 1.31 U g−1 dry biomass. The content of lignin in corn stover decreased by 42.30% after bio-pretreatment, and the conversion rate increased by 123.84% during the subsequent saccharification process in comparison with the untreated corn stover. Furthermore, the effects of bio-pretreatment on the structure of corn stover were presented using a scanning electron microscope (SEM), Brunauer-Emmet-Teller (BET), X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR). The results showed that M.V. is a promising lignin-degrading fungus. This research demonstrated an efficient pretreatment approach for enhancing the enzymatic saccharification of corn stover.

Assembly of direct-electron-transfer-type bioelectrodes with high performance

Direct electron transfer bioelectrocatalysis is an essential type of reaction for the development of bioelectrochemical devices such as biosensors, biofuel cells, and bioreactors. In this work, we performed several modifications of mesoporous electrodes to improve the heterogeneous electron transfer kinetics and the orientation of three different enzymes: bilirubin oxidase from Myrothecium verrucaria, hydrogenase from Desulfovibrio vulgaris Miyazaki F, and tungsten-containing formate dehydrogenase from Methylobacterium extorquens AM1. The results are discussed based on the curvature effects of mesoporous structures, the edge effect of the diffuse double layer around microporous structures, and the electrostatic interactions between enzymes and electrodes.

Three new tetralol analogs from soil-derived fungus Myrothecium verrucaria with anti-inflammatory activity

Three new tetralol analogs, myrochromanols A-C (1–3), together with 11 known trichothecenes (4–14), were isolated from a soil fungus Myrothecium verrucaria HL-P-1. The structures of the three new compounds were elucidated by extensive spectroscopic analysis including HRESIMS, NMR, and ECD calculation. All of the new compounds were tested for their anti-inflammatory activity and cytotoxicity. Compounds 1 and 3 inhibited lipopolysaccharide (LPS)-induced NO production in BV2 cells with IC50 values of 26.04 and 25.80 μM, respectively.

Emerging foliar and soil‐borne pathogens of leafy vegetable crops: a possible threat to Europe

Italy is one of the leading countries for the production and consumption of ready‐to‐eat salads. This has led to a steady increase in the area used over the last decade for the growth of leafy vegetables under intensive systems. The recent new diseases that affect lettuce, wild and cultivated rocket, lamb's lettuce, spinach and basil are reported here: Plectosphaerella cucumerina on wild rocket, endive and lamb's lettuce, Fusarium equiseti on wild and cultivated rocket and lettuce, Myrothecium verrucaria on spinach and wild rocket, Myrothecium roridum on lamb's lettuce, Allophoma tropica on lettuce and Alternaria sp. on basil and rocket are among the new foliar pathogens in Italy. Among the soil‐borne pathogens, Pythium aphanidermatum, Pythium irregulare and Pythium Cluster B2a have recently been isolated in Italy on spinach and Swiss chard, lamb's lettuce and lettuce, while Fusarium oxysporum f. sp. lactucae, which causes lettuce wilt, is gradually spreading to new countries. Some of the new pathogens have been found to be transmitted by seed and typical of tropical climate, and are thus favoured by the increases in temperature linked to climate change. The globalization of markets, climate change and intensive cultivation are among the factors responsible for the proliferation and spread of some of these new pathogens that are ‘alien’ to Italian production systems.

Nanoporous Gold-Based Biofuel Cells on Contact Lenses.

A lactate/O2 enzymatic biofuel cell (EBFC) was prepared as a potential power source for wearable microelectronic devices. Mechanically stable and flexible nanoporous gold (NPG) electrodes were prepared using an electrochemical dealloying method consisting of a pre-anodization process and a subsequent electrochemical cleaning step. Bioanodes were prepared by the electrodeposition of an Os polymer and Pediococcus sp. lactate oxidase onto the NPG electrode. The electrocatalytic response to lactate could be tuned by adjusting the deposition time. Bilirubin oxidase from Myrothecium verrucaria was covalently attached to a diazonium-modified NPG surface. A flexible EBFC was prepared by placing the electrodes between two commercially available contact lenses to avoid direct contact with the eye. When tested in air-equilibrated artificial tear solutions (3 mM lactate), a maximum power density of 1.7 ± 0.1 μW cm-2 and an open-circuit voltage of 380 ± 28 mV were obtained, values slightly lower than those obtained in phosphate buffer solution (2.4 ± 0.2 μW cm-2 and 455 ± 21 mV, respectively). The decrease was mainly attributed to interference from ascorbate. After 5.5 h of operation, the EBFC retained 20% of the initial power output.

Interaction of the Bioherbicide <i>Myrothecium verrucaria</i> with Technical-Grade Glyphosate on Glyphosate-Susceptible and -Resistant Palmer Amaranth

Previously we found that a strain of Myrothecium verrucaria (MV) exhibited bioherbicidal activity against several important weeds, and that some commercial formulations of glyphosate applied with MV resulted in synergistic interactions that improved weed control efficacy. We also found that MV had bioherbicidal activity against glyphosate-resistant Palmer amaranth. We have also reported that some commercial formulations are inhibitory to MV. Our objectives were to test the effect of unformulated glyphosate (high purity, technical-grade glyphosate) alone and in combination with MV for bioherbicidal activity on glyphosate-susceptible and -resistant Palmer amaranth biotypes under greenhouse conditions and to examine technical-grade glyphosate on the growth of this bioherbicide. High purity glyphosate (without adjuvants/surfactants) was not toxic to MV growth and sporulation at concentrations up to 2.0 mM when grown on agar supplemented with the herbicide. Both biotypes were injured by MV and MV plus glyphosate treatments as early as 19 h after application (3 h after a dew period of 16 h). These injury effects increased and were more evident through the 6-day time course, when after 120 h the MV plus glyphosate treatment had killed all glyphosate-susceptible and -resistant plants. The interaction of glyphosate plus MV was synergistic toward the control of Palmer amaranth. Data strongly suggest that the active ingredient is responsible for the synergy previously found when this bioherbicide was combined with some commercial formulations of glyphosate. Results demonstrated that MV can control both glyphosate-resistant and -susceptible Palmer amaranth seedlings and act synergistically with high-purity glyphosate to provide improved weed control.

Improvement of bilirubin oxidase productivity of <i>Myrothecium verrucaria</i> and studies on the enzyme overproduced by the mutant strain in the solid-state fermentation

Bilirubin oxidase has applications in the health and environmental sectors. Hence, several attempts have been made to increase enzyme yields. However, improvements were not very high. We report here the development of a mutant strain of Myrothecium verrucaria by using UV-rays, which produced 28.8 times more enzyme compared with the parent and was higher than the yields reported in earlier submerged cultures. The mutant strain produced 35.6 times more enzyme than the parent in solid-state fermentation, which is better than that previously reported for a solid-state fermentation process. The specific activity of the enzyme produced by the mutant was higher than that of the parental enzyme. Bilirubin oxidase from both strains showed an optimum activity at pH 7 and 40°C. However, the time required to inactivate half of the initial enzyme activity at 60°C was much higher in the case of the enzyme obtained from the mutant compared with the parental enzyme. The improved thermostability of the enzyme from the mutant strain could be due to the point mutations induced during the UV irradiation, since there was no change in the mass of the enzyme compared with the parental enzyme. The bilirubin oxidase of the mutant strain degraded the bilirubin faster than the enzyme obtained from the parent under similar conditions. Faster activity of the enzyme obtained from the mutant strain could be due to its lower Km (79.4 μM) compared with that of the parental enzyme (184 μM). Hence, the mutant enzyme showed a better functionality and thermostability, which will be beneficial for industrial applications.

Potential pulse-assisted immobilization of Myrothecium verrucaria bilirubin oxidase at planar and nanoporous gold electrodes

A potential pulse-assisted approach was used to immobilize Myrothecium verrucaria bilirubin oxidase at planar and nanoporous gold electrodes (NPG) containing pores of ca. 20nm and ca. 40nm in diameter. An increase in the current due to the bioelectrocatalytic reduction of oxygen by MvBOD-modified gold electrodes obtained from a 20μL drop by the proposed pulse-assisted approach was observed when compared to the response obtained with electrodes modified by drop-casting. This increase likely arises from a preferential orientation of MvBOD molecules at the planar gold surface obtained by fast switching of the potential pulses between opposite charges. The concomitant ion stirring effect induces the attraction of the enzymes to the charged gold surface and forces access to the internal pore volume of the NPG. Immobilization of MvBOD using the potential pulse-assisted approach significantly increases current densities by facilitating the electron transfer between the enzyme and the electrode surface.

Rechargeable, flexible and mediator-free biosupercapacitor based on transparent ITO nanoparticle modified electrodes acting in µM glucose containing buffers

We present a transparent and flexible self-charging biosupercapacitor based on an optimised mediator- and membrane-free enzymatic glucose/oxygen biofuel cell. Indium tin oxide (ITO) nanoparticles were spray-coated on transparent conducting ITO supports resulting in a flocculent, porous and nanostructured electrode surface. By this, high capacitive currents caused by an increased electrochemical double layer as well as enhanced catalytic currents due to a higher number of immobilised enzyme molecules were obtained. After a chemical pre-treatment with a silane derivative, bilirubin oxidase from Myrothecium verrucaria was immobilized onto the ITO nanostructured electrode surface under formation of a biocathode, while bioanodes were obtained by either immobilisation of cellobiose dehydrogenase from Corynascus thermophilus or soluble PQQ-dependent glucose dehydrogenase from Acinetobacter calcoaceticus. The latter showed a lower apparent KM value for glucose conversion and higher catalytic currents at µM glucose concentrations. Applying the optimised device as a biosupercapacitor in a discontinuous charge/discharge mode led to a generated power output of 0.030mW/cm2 at 50µM glucose, simulating the glucose concentration in human tears. This represents an enhancement by a factor of 350 compared to the power density obtained from the continuously operating biofuel cell with a maximum power output of 0.086µW/cm2 under the same conditions. After 17h of charging/discharging cycles a remarkable current enhancement was still measured. The entire device was transferred to flexible materials and applied for powering a flexible display showing its potential applicability as an intermittent power source in smart contact lenses.

Degradation of lignin in birch sawdust treated by a novel Myrothecium verrucaria coupled with ultrasound assistance

Combined treatment of a novel fungal endophyte Myrothecium verrucaria coupled with ultrasound assistance was conducted to enhance lignin degradation in birch sawdust. The optimum treatment conditions were confirmed as the materials to liquid ratio 1:20, temperature 30°C, time 4days and pH 7, respectively. The results showed that the combined treatment led to the lignin degradation reaching 67.95±2.14%, while the lignin degradation were 45.50±2.12% and 13.75±0.66% with separate fungal treatment and ultrasound treatment, respectively. Moreover, SEM and FTIR analysis indicated that combined treatment significantly altered surface morphology and chemical structure of birch sawdust. The combined treatment greatly increased lignin removal during short time in mild environment. Therefore, these results demonstrated that the combined treatment of fungal endophyte coupled with ultrasound assistance has the high potential for the removal lignin in lignocellulose.

Myrothecium verrucaria causing needle blight disease on Blue pine (Pinus wallichiana): molecular characterization and host range

Laboratory and nursery experiments were conducted to identify the causal agent of a needle blight of Pinus wallichiana, a species native to the Western Himalayas. The pathogen was identified as Myrothecium verrucaria, on the basis of morphological, cultural and molecular characterization. BLAST analysis of ITS sequences of the pathogen revealed maximum sequence identity of 99% with M. verrucaria. The sequence is the first of this fungus from P. wallichiana. Phylogenetic analysis grouped all M. verrucaria isolates in a single clade; M. roridum and M. inundatum clustered in separate clades. The pathogen grew optimally at 25 ± 1 °C on oat meal agar, pH 5.5. Inoculation experiments with M. verrucaria demonstrated pathogenicity on Pinus halepensis, Cedrus deodara and Cryptomeria japonica, in addition to Pinus wallichiana.