METABOLISM OF HALOGENATED COMPOUNDS IN THE WHITE-ROT FUNGUS BJERKANDERA-ADUSTA STUDIED BY MEMBRANE INLET MASS-SPECTROMETRY AND TANDEM MASS-SPECTROMETRY
Hc. Beck et al., METABOLISM OF HALOGENATED COMPOUNDS IN THE WHITE-ROT FUNGUS BJERKANDERA-ADUSTA STUDIED BY MEMBRANE INLET MASS-SPECTROMETRY AND TANDEM MASS-SPECTROMETRY, Biotechnology and bioengineering, 51(1), 1996, pp. 23-32
Membrane inlet mass spectrometry has been used for the characterizatio
n of halogenated organic compounds produced by the fungus Bjerkandera
adusta. Using this technique we obtained electron impact-, chemical io
nization-, electron capture negative chemical ionization-mass spectra
and tandem mass spectra directly from the growth medium. Through this
direct analysis of the samples we identified novel bioconversion produ
cts and confirmed recently published data on the production of both ch
lorinated and brominated methoxybenzaldehyde metabolites. Growth profi
les of the culture grown on a defined medium showed that the productio
n of secondary metabolites starts after approximately 6 days and reach
es maximal concentrations of 25-250 mu M after 15-20 days. Although de
layed, the production of secondary metabolites paralleled a depletion
of glucose from the medium acid stopped shortly after all glucose had
been consumed. Experiments in which fluoro- and bromo-labeled 4-methox
ybenzaldehydes were added to the medium at day 8 showed biotransformat
ion of these compounds into chloro-3-fluoro-4-methoxybenzaldehyde and
chloro-3-bromo-4-methoxybenzaldehyde, respectively. No dichlorinated p
roducts were observed, suggesting that halogenation takes place only a
t the meta position on the 4-methoxybenzaldehydes. These experiments a
re the first to bring direct evidence of a halogenation mechanism, wh
ere the enzymatic attack takes place directly on the 4-methoxybenzalde
hyde intermediates. (C) John Wiley & Sons, Inc.