RESUMO
Polygalacturonase (PG) production by Fomes sclerodermeus using solid-state fermentation (SSF) was carried out. Maximal PG activity (26 U/gdw) was obtained between days 11 and 13 at the end of exponential growth. PG activity in the crude extract was more stable at pH 5-6 and 30 °C and had optimum activity at pH 5 and 50 °C. Optimal conditions for PG extraction were: one time extraction with Na2SO4 as solvent with 10 min. of agitation. In a scale-up system, PG activity per gram of dry substrate decreased about 60% compared with the activity obtained in an Erlenmeyer flask; however, high total PG activity was obtained.
Se estudió la producción de poligalacturonasa (PG) por Fomes sclerodermeus usando técnicas de fermentación en estado sólido. La actividad PG máxima (26 U/g ps) fue observada entre los días 11 y 13. La actividad PG en los extractos crudos fue más estable a pH 5-6 y 30 °C, con una actividad óptima a pH 5 y a 50 °C. Las condiciones óptimas para la extracción de PG se lograron con una única extracción empleando Na2SO4 como solvente, con 10 minutos de agitación. En el escalado del sistema, la actividad PG por gramo de peso seco de sustrato disminuyó cerca de 60% comparada con la obtenida en frascos Erlenmeyer, pero la actividad total fue mayor.
Assuntos
Coriolaceae/enzimologia , Proteínas Fúngicas/isolamento & purificação , Poligalacturonase/isolamento & purificação , Fracionamento Celular/métodos , Coriolaceae/crescimento & desenvolvimento , Fermentação , Concentração de Íons de Hidrogênio , Micologia/métodos , Solventes , TemperaturaRESUMO
Pine-needle degradation by Stereum hirsutum was studied under conditions of solid state fermentation with the aim of accelerating its decomposition, avoiding the accumulation in situ and in view of the possible utilization of the residual organic matter. Three experimental systems were tested: pine needles alone and with the addition of either a nitrogen source or barley grain. Determinations were made at 14 and 28 days of incubation. All treatments showed substrate degradation. The addition of a nitrogen source raised enzymatic activities measured but not the degree of degradation. Grain addition resulted in higher biomass, enzyme activities, sugar accumulation and degradation of the substrate. Fungal biomass estimated as N-acetyl glucosamine allowed calculation of the actual degradation of the substrate, that reached 19
at 28 d of culture without additions and 44
at 14 d in pine-needles with grain.