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Appl. Environ. Microbiol., Aug 1997, 3059-3067, Vol 63, No. 8
LK Hardison, SS Curry, LM Ciuffetti and MR Hyman
In this study, evidence for two novel metabolic processes catalyzed by a
filamentous fungus, Graphium sp. strain ATCC 58400, is presented. First,
our results indicate that this Graphium sp. can utilize the widely used
solvent diethyl ether (DEE) as the sole source of carbon and energy for
growth. The kinetics of biomass accumulation and DEE consumption closely
followed each other, and the molar growth yield on DEE was
indistinguishable from that with n-butane. n-Butane-grown mycelia also
immediately oxidized DEE without the extracellular accumulation of organic
oxidation products. This suggests a common pathway for the oxidation of
both compounds. Acetylene, ethylene, and other unsaturated gaseous
hydrocarbons completely inhibited the growth of this Graphium sp. on DEE
and DEE oxidation by n-butane-grown mycelia. Second, our results indicate
that gaseous n-alkane-grown Graphium mycelia can cometabolically degrade
the gasoline oxygenate methyl tert-butyl ether (MTBE). The degradation of
MTBE was also completely inhibited by acetylene, ethylene, and other
unsaturated hydrocarbons and was strongly influenced by n-butane. Two
products of MTBE degradation, tert-butyl formate (TBF) and tert-butyl
alcohol (TBA), were detected. The kinetics of product formation suggest
that TBF production temporally precedes TBA accumulation and that TBF is
hydrolyzed both biotically and abiotically to yield TBA. Extracellular
accumulation of TBA accounted for only a maximum of 25% of the total MTBE
consumed. Our results suggest that both DEE oxidation and MTBE oxidation
are initiated by cytochrome P-450-catalyzed reactions which lead to
scission of the ether bonds in these compounds. Our findings also suggest a
potential role for gaseous n-alkane-oxidizing fungi in the remediation of
MTBE contamination.
Copyright © 1997, American Society for Microbiology
Metabolism of Diethyl Ether and Cometabolism of Methyl tert-Butyl Ether by a Filamentous Fungus, a Graphium sp
Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331-2902
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