Acyl CoA oxidase activity from Beauveria bassiana an entomopathoghenic fungus

TERESA ALCONADA; PATRICIA JUÁREZ

Cataratas del Iguazú

Congreso; XL Reunión Anual de la Sociedad Argentina de Investigaciones Bioquímicas; 2004

SSociedad Argentina de Investigaciones Bioquímicas y Biología Molecula

ACYL COA OXIDASE ACTIVITY FROM BEAUVERIA BASSIANA, AN ENTOMOPATHOGENIC FUNGUS.Alconada, Teresa and Juárez, Patricia.Instituto de Investigaciones Bioquímicas de La Plata (CONICET-UNLP), Facultad de Ciencias Médicas, calles 60 y 120 (1900) La Plata, Argentina e-mail: mjuarez@isis.unlp.edu.arThe entomopathogenic fungus Beauveria bassiana has the ability to degrade a variety of hydrocarbon structures similar or identical to those of their insect host, incorporating their degradation products into different fungal lipids. After the initial oxidation step, the fatty acid product becomes the substrate of acyl CoA oxidases (ACO). B. bassiana was grown on glucose supplemented medium (FS0) or hydrocarbon supplemented medium (FS2). The ACO activity was studied by spectrophotometry, based on the determination of H2O2 production coupled to the oxidation of 2',7'- dichlorofluorescin diacetate in a reaction catalysed by exogenous peroxidase. The ACO activity was analyzed in the P20000g fractions from FS0 and FS2 cultures. Activity was measured employing acyl CoA's of 18 to 24 carbons. Higher activities were always detected for FS2 cultures in the conditions tested, i.e., using stearoyl-CoA as the substrate a 32% increment in activity was observed. Employing larger chain length acyl-CoA´s, tetracosane-grown cultures showed the highest activity with lignoceroyl CoA. This assay is quite sensitive and offers a simple approach for detection of ACO activity. The activity was linear until 20 min of incubation and up to 30 g/l of protein concentration. These studies will contribute to help understand the metabolic pathways involved in hydrocarbon degradation by entomopathogenic fungi, playing an important role in the biocontrol of insects.