Acyl-CoA oxidase activity from Beauveria bassiana, an entomopathogenic fungus

ALCONADA TERESA, JUÁREZ M. PATRICIA

JOURNAL OF BASIC MICROBIOLOGY

John Wiley & Sons, Inc.

Lugar: Londres; Año: 2006 vol. 46 p. 435 - 443

0233-111X

Abstract Beauveria bassiana produces acyl-Co oxidase (ACO) in the P20000 g fraction of  glucose and alkane-grown cultures that catalyze the oxidation of acyl-CoAs of different chain length. The activity was measured indirectly over the formation of H2O2 via the oxidative-coupled assay system. ACO activity was assessed spectrophotometrically in the P20000g fraction of glucose-grown (FS0) and n-alkane grown cultures (FSalk), employing acyl-CoAs of 16 to 24 carbons as substrates. A significant increment in the activity was observed in FSalk as compared to that of controls (FS0) in all conditions tested. Tetracosane-grown cultures showed the highest activity with lignoceroyl-CoA. The reaction conditions were optimized employing lignoceroyl-CoA as substrate. A variable lag phase was observed  when the activity was measured as a function of time. In the presence of  3- amino-1,2,4-triazole (AT) to prevent H2O2 consumption by endogenous catalase, the lag phase became shorter and disappeared when AT concentrations were raised from 40 to 200 mM, thus enhancing acyl-CoA oxidation. Enzyme activity reached its maximal value in the presence of 240 mg peroxidase, 0.08 % Triton X-100 and 36 mM bovine serum albumin. The apparent Km using lignoceroyl as substrate was estimated 2.5 mM. ACO showed high activity and stability between 30 and 40ºC, as well as between 7.0 and 9.0 pH, for 120 min,  being 7.0 the optimum pH. Keywords: Entomopathogenic fungi;  Beauveria bassiana; Acyl-CoA oxidase; Very long chain hydrocarbons.