RESUMO
The white rot basidiomycete Ganoderma lucidum was evaluated for its capability to tolerate and to degrade the herbicide diuron. Diuron at a subtoxic concentration was added at the start of the cultivation in glucose liquid stationary cultures. Under this condition diuron was a laccase inducer. Almost 50% of the initially present diuron was removed after 15 d of cultivation. Two diuron metabolites were found N'-(3,4-dichlorophenyl)-N-methylurea (DCPMU) and 3,4-dichlorophenylurea (DCPU). The addition of the cytochrome P450 inhibitors 1-aminobenzotriazole and piperonyl butoxide reduced significantly the capability of the fungus in degrading diuron. The activities of superoxide dismutase and catalase were significantly increased in the mycelial extracts by the presence of diuron. On the other hand, diuron did not cause any significant alteration in the levels of reactive oxygen species. Additionally, laccase could also degrade diuron in vitro and this degradation was increased by the addition of synthetic mediators, 3-ethylbenzthiazoline-6-sulphonic acid and acetylacetone. Significant reduction in the toxicity, as evaluated by the Lactuca sativa bioassay, was observed after G. lucidum treatment. In conclusion, G. lucidum is able to metabolize diuron by intra- and extracellular mechanisms, without the accumulation of toxic products.
Assuntos
Diurona/metabolismo , Farmacorresistência Fúngica , Herbicidas/metabolismo , Reishi/metabolismo , Biotransformação , Catalase/metabolismo , Diurona/farmacologia , Herbicidas/farmacologia , Lacase/metabolismo , Pentanonas/farmacologia , Butóxido de Piperonila/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Reishi/efeitos dos fármacos , Superóxido Dismutase/metabolismo , Triazóis/farmacologiaRESUMO
Ganoderma lucidum (Curtis) P. Karst is a white rot fungus that is able to degrade the lignin component in wood. The ability of two strains of this species to produce the ligninolytic enzyme laccase was assessed. After the evaluation of induction with heavy metals and phenolic compounds, it was found that among the tested substances, copper and ferulic acid are the best laccase inducers. It was also observed that the two types of inducers (phenolic and metallic) produce different electrophoretic patterns of laccase activity. Optimized concentrations of inducers were obtained through a factorial design and the thermal stability of optimized supernatants was studied at a wide range of acidic pH. We found that the enzyme is more thermostable at higher pH values.
Assuntos
Lacase/biossíntese , Reishi/efeitos dos fármacos , Reishi/metabolismo , Cobre/farmacologia , Ácidos Cumáricos , Manganês/farmacologia , Fenóis/farmacologiaRESUMO
Ganoderma lucidum (Curtis) P. Karst es un hongo causante de pudrición blanca, capaz de degradar la lignina de la madera y otros sustratos en los que crece. En este trabajo se evaluó la capacidad de dos cepas de esta especie de producir la enzima ligninolítica lacasa. Asimismo, se ensayó la inducción de esta enzima con diferentes compuestos fenólicos e iones metálicos, y se encontró que el ácido ferúlico y el cobre fueron los mejores inductores de la lacasa entre los agentes evaluados. También se encontró que los dos tipos de inductores (fenólicos y metálicos) producen distintos patrones electroforéticos de actividad lacasa. Las concentraciones óptimas de los inductores fueron establecidas mediante un diseño factorial. Se estimó la estabilidad térmica de la lacasa en un amplio rango de pH ácidos, y se comprobó que a pH más altos la enzima es más termoestable.
Ganoderma lucidum (Curtis) P. Karst is a white rot fungus that is able to degrade the lignin component in wood. The ability of two strains of this species to produce the ligninolytic enzyme laccase was assessed. After the evaluation of induction with heavy metals and phenolic compounds, it was found that among the tested substances, copper and ferulic acid are the best laccase inducers. It was also observed that the two types of inducers (phenolic and metallic) produce different electrophoretic patterns of laccase activity. Optimized concentrations of inducers were obtained through a factorial design and the thermal stability of optimized supernatants was studied at a wide range of acidic pH. We found that the enzyme is more thermostable at higher pH values.
Assuntos
Lacase/biossíntese , Reishi/efeitos dos fármacos , Reishi/metabolismo , Ácidos Cumáricos , Cobre/farmacologia , Manganês/farmacologia , Fenóis/farmacologiaRESUMO
Ganoderma lucidum (Curtis) P. Karst is a white rot fungus that is able to degrade the lignin component in wood. The ability of two strains of this species to produce the ligninolytic enzyme laccase was assessed. After the evaluation of induction with heavy metals and phenolic compounds, it was found that among the tested substances, copper and ferulic acid are the best laccase inducers. It was also observed that the two types of inducers (phenolic and metallic) produce different electrophoretic patterns of laccase activity. Optimized concentrations of inducers were obtained through a factorial design and the thermal stability of optimized supernatants was studied at a wide range of acidic pH. We found that the enzyme is more thermostable at higher pH values.
Assuntos
Lacase/biossíntese , Reishi/efeitos dos fármacos , Reishi/metabolismo , Cobre/farmacologia , Ácidos Cumáricos , Manganês/farmacologia , Fenóis/farmacologiaRESUMO
Bioremediation of contaminated sites by biosorption of pollutants onto a wide range of materials has emerged as a promising treatment for recalcitrant aromatic compounds or heavy metals. When adsorption occurs on living white-rot fungi mycelia, the pollutants may be degraded by ligninolytic enzymes. However, the survival of mycelia in harsh conditions is one of the drawbacks of those methodologies. In this study, it was demonstrated that culture media supplemented with several guaiacol derivatives (vanilloids) increased the resistance of Ganoderma lucidum E47 cultures to chemical stress by enhancing the adsorptive capacity of the extracellular mucilaginous material (ECMM). The toxicity of the fungicides gentian violet (GV), malachite green (MG) and clotrimazole, and the heavy metal Cadmium was noticeably diminished in fungal cultures supplemented with the guaiacol derivative vanillic acid (VA). No degradation of the tested compounds was detected. The activity of the oxidative enzymatic systems like laccase, a well-known oxidase associated to dye degradation, was only detectable after complete growth on plates. Extremely low concentrations of VA caused a significant protective effect, radial extension of the growth halo in plates supplemented with 0.0001 mM of VA plus GV was up to 20% to that obtained in control plates (without addition of GV and VA). Therefore, the protective effect could not be attributable to VA per se. ECMM separated from the mycelium exhibited a much higher increase in the adsorptive capacity when isolated from liquid cultures containing VA, while that obtained from unsupplemented cultures showed an almost null adsorptive capacity.