Metabolism of L-phenylalanine in the lignin-degrading white-rot fungi bjerkandera adusta and ischnoderma benzinum

摘要

Two white rot lignin degrading fungi Bjerkandera adusta and ischnoderma benzoinum were cultinvated on a liquid medium suppleneted with L-phenylalanine, a precrsor for benzaldehyde (bitter almond aroma) and benzyl alochol. Remarkable amounts of behzaldehyde (587 mg/1) were only found in immobilized (on polyuretane foam cubes) cell cultures of Bjerkandera adusta. Benzyl alohol was produced by both strains (340 mg/1). An extracellular aryl-alcohol oxidase (AAO) activity was only detected in the fungus Bjerkandera adusta. Previously published results show that AAO activity was significantly enjanced in immobilized cells cultures, suggesting that it could play an important role in benzaldehyde biosynthesis (Lapadatescu et al. 1997). Aryl metabolites produced were identified for both strains by GC-MS analyuses. Tracer studies experiments using ~(14)C-and~(13)C-labelled L-phenylalanine were emplyed with B. adusta. A metabolic pathway for B. adusta was proposed.