Primera evidencia de actividad enzimática nitrilasa en Xylaria sp., y su relación con la biosíntesis de ácido indol-3-acético / First evidence of nitrilase enzymatic activity of Xylaria sp. and its relationship with the biosynthesis of indole-3-acetic acid

Resumen Muchos de los hongos degradadores de madera están implicados en la síntesis de metabolitos bioactivos de naturaleza antimicrobiana y terapéutica, así como de compuestos de importancia biotecnológica, incluyendo derivados indólicos, entre otros. Estos hongos brindan ciertos beneficios ecológicos a las plantas, entre los que se destacan la protección contra fitopatógenos y la promoción del crecimiento radicular. Xylaria sp. es un hongo degradador de celulosa (lignocelulolítico) con potencial biotecnológico. El ácido indol-3-acético (AIA) desempeña un papel sumamente importante en las interacciones planta-microorganismo, ya que es esencial para la fisiología y el correcto desarrollo morfológico vegetal. Se sabe que las enzimas nitrilo-hidrolíticas (nitrilasas) están involucradas en la síntesis de compuestos indólicos en las plantas, no obstante, se dispone de poca información acerca de la naturaleza de estas enzimas en el reino de los hongos. A través de una aproximación bioquímica y de genética molecular, se demuestra por primera vez que Xylaria sp. posee actividad enzimática nitrilasa utilizando compuestos ricos en nitrógeno y carbono como sustrato. La cepa estudiada aumentó sus niveles de expresión génica relativa y mostró crecimiento micelial, ambos en presencia de compuestos químicos como cianobenceno y KCN. Los resultados de este trabajo sugieren que el microorganismo es capaz de degradar moléculas nitrogenadas complejas. Por otra parte, mediante biofertilización con extractos fúngicos, se observó que Xylaria sp. promueve el desarrollo del sistema radicular de plántulas de Arabidopsis thaliana, además de sintetizar AIA.

Abstract Endophytic fungi inhabit plant tissues internally and asymptomatically, and many of them are involved in the synthesis of bioactive metabolites of antifungal and therapeutic nature, as well as other compounds of biotechnological importance including indole derivatives, among many others. Ecologically, they provide some benefits to plants including protection against phy-topathogens and promotion of root growth. In this sense, Xylaria sp. is a cellulose-decomposing fungus with biotechnological potential. It is worth mentioning that indole-3-acetic acid (IAA) also plays an extremely important role in plant-micro-organism interactions, as it is essential for physiology and proper plant morphological development. It is known that nitrile-hydrolytic enzymes (nitrilases) are involved in the synthesis of plant indole compounds; however, relatively little information is available concerning the nature of these enzymes in the fungal kingdom. In view of the above, through a biochemical and molecular-genetic approach, it has been demon-strated for the first time that Xylaria sp. carries out nitrile-hydrolytic enzyme activity using nitrogen and carbonrich compounds as substrate. The studied strain increased its relative gene expression levels and showed mycelial growth, both in the presence of chemical compounds such as cyanobenzene and KCN. Thus, the results of this work suggest that the micro-organism is capable of degrading complex nitrogenous molecules. On the other hand, through fungal biofertilization, it was observed that Xylaria sp. promotes the development of the root system of Arabidopsis thaliana seedlings, in addition to synthesizing IAA.

Steroids and dihydroisocoumarin glycosides from Xylaria sp. by the one strain many compounds strategy and their bioactivities / 中国天然药物

The fungus Xylaria sp. KYJ-15 was isolated from Illigera celebica. Based on the one strain many compounds (OSMAC) strategy, the strain was fermented on potato and rice solid media, respectively. As a result, two novel steroids, xylarsteroids A (1) and B (2), which are the first examples of C28-steroid with an unusual β- and γ-lactone ring, respectively, along with two new dihydroisocoumarin glycosides, xylarglycosides A (3) and B (4), were identified. Their structures were elucidated by spectroscopic methods, X-ray diffraction and electronic circular dichroism (ECD) experiments. All isolated compounds were evaluated for cytotoxicity, DPPH radical scavenging activity, acetylcholinesterase inhibitory and antimicrobial effect. Compound 1 exhibited potent AChE inhibitory activity with an IC50 value of 2.61 ± 0.05 μmol·L-1. The β-lactone ring unit of 1 is critical for its AChE inhibitory activity. The finding was further confirmed through exploring the interaction of 1 with AChE by molecular docking. In addition, both compounds 1 and 2 exhibited obvious antibacterial activity against Bacillus subtilis with a minimum inhibitory concentration (MIC) of 2 μg·mL-1. Compounds 3 and 4 exhibited antibacterial activities against Staphylococcus aureus with MICs of 4 and 2 μg·mL-1, respectively, which also exhibited DPPH radical scavenging activity comparable to the positive control with IC50 values of 9.2 ± 0.03 and 13.3 ± 0.01 μmol·L-1, respectively.

Secondary metabolites of endophyte fungi Xylaria sp. from Coptis chinensis / 中国中药杂志

Two new polyketides, lasobutone A(1) and lasobutone B(2), along with three known compounds, guignardianone C(3), guignardic acid(4), and 4-hydroxy-17R-methylincisterol(5), were isolated from the endophytic fungi Xylaria sp. by silica gel, MCI, and preparative HPLC, which was separated from the Chinese medicinal material Coptis chinensis and cultivated through solid fermentation with rice. Their structures were elucidated on the basis of spectroscopic methods, such as MS, NMR, IR, UV, and ECD. Compounds 2 and 4 showed inhibitory activities against the nitric oxide(NO) production in the LPS-induced macrophage RAW264.7 with IC_(50) values of 58.7 and 42.5 μmol·L~(-1) respectively, while compound 5 exhibited cytotoxic activities against HT-29 with IC_(50) value of 14.3 μmol·L~(-1).

Scanning Electron Microscopy (SEM) investigation of Polystyrene damage due to colonization by locally isolated Xylaria sp

@#<p style="text-align: justify;"><strong>BACKGROUND AND OBJECTIVES</strong>: Colonization of microorganisms on pollutants is the first indication of the potential ability of microbes to utilize plastic pollutants as a carbon source by sequential biodegradation into usable form for sustenance. The Philippines is considered the third highest country contributing to global mismanaged plastic waste. To locally manage and find a natural and innovative solution to this worldwide concern, this study aimed to evaluate the capacity of Xylaria sp. SDM (sterile dark mycelia) wild type, which was previously reported to colonize polyethylene plastic and mutant strains to colonize polystyrene, a plastic pollutant widely produced in the world. Assessment of the ability of local Xylaria sp. strains to grow, penetrate, and damage the surface and inner structures of polystyrene was investigated using scanning electron microscopy (SEM).</p><p style="text-align: justify;"><strong>METHODOLOGY:</strong> Xylaria sp. strains were cultured in a pH 5.0 mineral medium with 0.5% glucose as carbon source and polystyrene as a co-carbon source, and stored at 25?C for 50 days. At the end of the incubation period, due to irremovable fungal strains on the surface of the polystyrene strips, samples of polystyrene from each strain were subjected to SEM.</p><p style="text-align: justify;"><strong>RESULTS:</strong> On the 20th day of incubation, the presence of mucilaginous sheaths and fungal growth was observed on the surface of treated polystyrene strips. At the end of the 50-day incubation period, scanning electron microscopy (SEM) confirmed fungal growth and colonization, through the presence of mycelial mats and hyphae, of the wild type and mutant strains on the surface and inner structures of polystyrene except the control. Moreover, physical surface damage in the form of holes, cracks, and crevices on polystyrene demonstrated the active burrowing action of Xylaria sp. strains further supporting the potential of this fungus to damage polystyrene plastic.</p><p style="text-align: justify;"><strong>CONCLUSION:</strong> Whereas fungal growth on a polymer surface is necessary but not sufficient to conclude the process of carbon assimilation as the final biodegradation step, the initial colonization of Xylaria sp. strains on polystyrene supports its ability to establish itself and physically damage the pollutant. Hence, this study extended the existing knowledge on the colonizing ability of Xylaria sp. on plastic making it a potential candidate organism to biodegrade plastic waste, which is one of the topmost environmental waste hazards in the world today.</p>

Metabolites of endophytic fungus Xylaria sp. with biological activities / 中国药学杂志

OB JECTIVE: To investigate the chemical constituents from the fermented rice substrate of endophytic fungus Xylaria sp. HCCB03890. METHODS: The compounds were isolated with silica gel column chromatography and reversed-phase high performance liquid chromatography. The structures of these compounds were elucidated through MS and NMR spectroscopic analysis. The anti-microbes activities were evaluated by disk diffusion method, cytotoxic activities were determined by MTT method, and anti-HIV activities were measured by using a firefly luciferase assay system. RESULTS: Six compounds were isolated and identified as TV-acetyltyra-mine(1), schizostatin(2), piliformic acid(3), stigmast-5,22-dien-3-ol(4), dankasterone(5) and demethylincisterol(6) on the basis of spectroscopic data analyses. Compound 3 showed moderate anti-microbial activity. Compounds 4-6 exhibited cytotoxic and anti-HIV activities, especially, and compund 5 and 6 showed significant anti-HIV activities with IC50 values of 0.4 and 0.9 μg · mL, respectively. CONCLUSION: Compounds 2, 5 and 6 were for the first time isolated from Xylaria sp., moreover, 5 and 6 are for the first time found in terrestrial microbes.