Detection of manganese peroxidase and other exoenzymes in four isolates of Geastrum (Geastrales) in pure culture.

Knowledge regarding the enzymatic machinery of fungi is decisive to understand their ecological role. The species of the genus Geastrum are known to grow extremely slowly in pure culture, which makes it difficult to evaluate physiological parameters such as enzyme activity. Qualitative assays were performed on isolates of four species of this genus, showing evidence of laccase, cellulase, pectinase, amylase and lipase activity and suggesting that a wide range of carbon sources can be exploited by these species. For the first time in this genus, quantitative assays verified manganese peroxidase activity (up to 0.6mU/g) in 30-day old cultures, as well as laccase, ß-glycosidase and ß-xylosidase activities.

Detección de manganeso peroxidasa y otras exoenzimas en 4 aislamientos de Geastrum (Geastrales) en cultivo puro / Detection of manganese peroxidase and other exoenzymes in four isolates of Geastrum (Geastrales) in pure culture

Knowledge regarding the enzymatic machinery of fungi is decisive to understand their ecological role. The species of the genus Geastrum are known to grow extremely slowly in pure culture, which makes it difficult to evaluate physiological parameters such as enzyme activity. Qualitative assays were performed on isolates of four species of this genus, showing evidence of laccase, cellulase, pectinase, amylase and lipase activity and suggesting that a wide range of carbon sources can be exploited by these species. For the first time in this genus, quantitative assays verified manganese peroxidase activity (up to 0.6 mU/g) in 30-day old cultures, as well as laccase, β-glycosidase and β-xylosidase activities.

El conocimiento de la maquinaria enzimática de un hongo es decisivo para entender su rol ecológico. Las especies del género Geastrum son conocidas por su crecimiento extremadamente lento en cultivos puros, lo que hace difícil la evaluación de parámetros fisiológicos como las actividades enzimáticas. Se realizaron ensayos cualitativos sobre aislamientos de 4 especies de este género, mostrando evidencias de actividades lacasa, celulasa, pectinasa, amilasa y lipasa, mostrando el amplio rango de fuentes de carbono que pueden ser explotadas por estas especies. Ensayos cuantitativos verificaron por primera vez en este género la actividad manganeso peroxidasa (hasta 0,6 mU/g) en cultivos de 30 días, así como también β-glucosidasa y β-xilosidasa.

Deterioro de poliestireno expandido causado por Aureobasidium pullulans var. melanogenum / Deterioration of expanded polystyrene caused by Aureobasidium pullulans var. melanogenum

An expanded-polystyrene factory located in northern Buenos Aires reported unusual dark spots causing esthetic damage in their production. A fungal strain forming black-olive colonies on extract malt agar medium was isolated from the damaged material and identified as Aureobasidium pullullans var. melanogenum. This fungus is particularly known for its capacity to produce hydrolytic enzymes and a biodegradable extracellular polysaccharide known as pullulan, which is used in the manufacture of packaging material for food and medicine. Laboratory tests were conducted to characterize its growth parameters. It was found that the organism was resistant to a wide range of pHs but did not survive at temperatures over 65 °C. The proposed action plan includes drying of the material prior to packaging and disinfection of the machinery used in the manufacturing process and of the silos used for raw material storage.

Una fábrica de poliestireno expandido situada en el norte de Buenos Aires reportó casos inusuales de manchas oscuras que causaban un daño estético en su producción. A partir del material dañado se aisló una cepa de hongo que forma colonias negro-oliváceas en medio agar-malta y que fueron identificadas como Aureobasidium pullullans var. melanogenum. Este hongo es particularmente conocido por su capacidad de producir enzimas hidrolíticas y un polisacárido extracelular biodegradable, el pululano, utilizado para la fabricación de envases para alimentos y medicinas. Se llevaron a cabo ensayos de laboratorio para caracterizar sus parámetros de crecimiento. Se encontró que el organismo es resistente a un amplio rango de pH, pero no sobrevive a temperaturas superiores a 65 °C. El plan de acción propuesto incluye el secado del material antes de su envasado y la desinfección tanto de la maquinaria utilizada en el proceso de fabricación como de los silos utilizados para el almacenamiento de la materia prima.

Deterioration of expanded polystyrene caused by Aureobasidium pullulans var. melanogenum.

An expanded-polystyrene factory located in northern Buenos Aires reported unusual dark spots causing esthetic damage in their production. A fungal strain forming black-olive colonies on extract malt agar medium was isolated from the damaged material and identified as Aureobasidium pullullans var. melanogenum. This fungus is particularly known for its capacity to produce hydrolytic enzymes and a biodegradable extracellular polysaccharide known as pullulan, which is used in the manufacture of packaging material for food and medicine. Laboratory tests were conducted to characterize its growth parameters. It was found that the organism was resistant to a wide range of pHs but did not survive at temperatures over 65°C. The proposed action plan includes drying of the material prior to packaging and disinfection of the machinery used in the manufacturing process and of the silos used for raw material storage.