Abbau von L-Phenylalanin und von Phenylcarbonsäuren in Chloridazon-abbauenden Bakterien. Eine Kombination von Seitenkettenabbau und Dioxygenase-Weg

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Abstract
Strain N of chloridazon-degrading bacteria degrades phenylalanine via cis-2,3-dihydro-2,3-dihydroxyphenylalanine, 2,3-dihydroxyphenylalanine, aspartate and 4-hydroxy-2-oxovalerate. cis-2,3-Dihydro-2,3-dihydroxyphenylalanine, 2,3-dihydroxyphenylalanine, phenylpyruvate, cis-2,3-dihydro-2,3-dihydroxyphenylpyruvate, 2,3-dihydroxyphenylpyruvate, cis-2,3-dihydro-2,3-dihydroxyphenylacetate, 2,3-dihydroxyphenylacetate and 2,3-dihydroxybenzaldehyde are detectable in the medium of strain E during growth on phenylalanine. Incubation with phenylacetate, 3-phenylpropionate or 4-phenylbutyrate leads to the accumulation of the corresponding cis-2,3-dihydro-2,3-dihydroxyphenyl derivatives. These compounds are transformed with dihydrodiol dehydrogenase to 2,3-dihydroxyphenylacetate, 3-(2,3-dihydroxyphenyl)propionate and 4-(2,3-dihydroxyphenyl)butyrate. 3-(2,3-Dihydroxyphenyl)propionate is attacked by a catechol 2,3-dioxygenase and the meta-cleavage product is again cleaved by a hydrolase yielding succinate. In a similar reaction sequence the degradation of 4-phenylbutyrate leads to the formation of glutarate. Small amounts of 2-, 3- and 4-hydroxyphenylacetate were also isolated from the growth medium of strain E on phenylacetate. Resting cells metabolized 3- and 4-hydroxyphenylacetate via homogentisate and 3,4-dihydroxyphenylacetate. In the culture medium of strain K2AP- benzoate could be detected. Pathways for the degradation of phenylalanine and aromatic carboxylic acids in chloridazon-degrading bacteria are proposed.