title: Transformation of Metalaxyl by the Fungus Syncephalastrum racemosum.
abstract: The fungus Syncephalastrum racemosum (Cohn) Schroeter was found to transform the fungicide metalaxyl [N-(2,6-dimethylphenyl)-N-(methoxyacetyl)-alanine methyl ester] in pure culture. After 21 days of incubation in a basal medium amended with 5 mug of metalaxyl per ml, more than 80% of the compound was transformed by the fungus. The transformation rates decreased as the concentrations of metalaxyl increased from 5 to 100 mug/ml. No transformation was observed when the concentration of metalaxyl was higher than 200 mug/ml. Two isomeric metabolites and a mixture of two other isomeric metabolites were isolated from the organic extract of the growth medium and identified as N-(2-methyl-6-hydroxymethylphenyl)-N- and N-(2-hydroxymethyl-6-methylphenyl)-N-(methoxyacetyl)-alanine methyl ester and N-(3-hydroxy- and N-(5-hydroxy-2,6-dimethyl-phenyl)-N-(methoxyacetyl)-alanine methyl ester according to their mass-spectral and nuclear magnetic resonance-spectral characteristics. Benzylic hydroxylation of the methyl side chains and/or aromatic hydroxylation appeared to be the major reactions involved in the metabolism of metalaxyl.
authors.affiliation: Laboratory of Soil Biochemistry, Department of Agronomy, The Pennsylvania State University, University Park, Pennsylvania 16802.
authors.forename: Z
authors.initials: Z
authors.lastname: Zheng
authors.forename: S Y
authors.initials: SY
authors.lastname: Liu
authors.forename: A J
authors.initials: AJ
authors.lastname: Freyer
authors.forename: J M
authors.initials: JM
authors.lastname: Bollag