BIOSYNTHETIC-PATHWAY FOR HALOGENATED METHOXYBENZALDEHYDES IN THE WHITE-ROT FUNGUS BJERKANDERA-ADUSTA

Through experiments with fluoro-labelled phenylalanine, tyrosine and b enzaldehyde, the biochemical pathway leading to the chlorinated methox ybenzaldehydes in the white rot fungus Bjerkandera adusta has now been verified. Cultures of this organism supplied with fluoro-labelled phe nylalanine, tyrosine or benzaldehyde showed a bioconversion of these c ompounds into fluoro-4-methoxybenzaldehyde, fluoro-3-chloro-4-methoxyb enzaldehyde and fluoro-3,5-dichloro-4-methoxybenzaldehyde In addition fluoro-phenylalanine also yielded fluorobenzaldehyde. FIuorodichlorina ted compounds were only detected in cultures supplied with ortho subst ituted fluoro-phenylalanine demonstrating a meta specific halogenation mechanism. These results are the first to give direct;evidence of the involvement of both tyrosine and phenylalanine in the biosynthetic pa thway of chloromethoxy substituted benzaldehydes in B. adusta and sugg est a pathway for the biosynthesis of 3-chloro-4-methoxybenzaldehyde a nd 3,5-dichloro-4-methoxybenzaldehyde that proceeds either via phenyla lanine through benzaldehyde and 4-methoxybenzaldehyde or via tyrosine through 4-methoxybenzaldehyde.