Aromatic metabolism by a 2,4-D degrading Arthrobacter sp.

Abstract

A hypothesis that low molecular weight aromatic compounds, which occur naturally in the soil, may act as alternative substrates or inducers for the 2,4-dichlorophenoxyacetate (2,4-D) degrading enzyme system of an Arthrobacter sp. and maintain this enzyme system in the absence of 2,4-D, was examined experimentally. In a nonmanometric resting cell experiment, the 2,4-D adapted Arthrobacter sp. rapidly degraded 6 of the 12 aromatic compounds tested, and these 6 compounds were tested further with 2 additional aromatic compounds in manometric experiments with 2,4-D grown and citrate-grown cells. Homogentisic acid and catechol were oxidized more rapidly by 2,4-D grown cells than by cells grown on citrate medium. Thus, these two compounds could serve as alternative substrates for the 2,4-D degrading enzyme system of the Arthrobacter sp. In further manometric experiments, the 2,4-D degrading enzyme system in cells adapted to 2,4-dichlorophenol, catechol, or sodium benzoate was not induced.