Microbial degradation of xenobiotic compounds in soil columns

Abstract

Aerated soil columns were tested with respect to their suitability for the enrichment of bacterial strains with specific capabilities of degrading xenobiotic compounds and for studying microbial degradation processes in soil. Investigations were performed on degradation of phenoxyalkanoic acid herbicides and chlorinated anilines. Complete degradation of 0.1 g 1-1 3,4-dichlorophenoxy-alkanoic acids was reached within 1 week of incubation. Duration of lag phases preceding degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) was dependent on substrate concentration. Lag periods prior to degradation of relatively highly concentrated solution of 2,4-D (1.0 g 1-1) were significantly shortened by preincubation with lower concentrations of 2,4-D (0.02 g 1-1). Complete degradation of 0.2 g 1-1 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) was obtained after 130 days of incubation. After incubation with monochloroanilines and stepwise increasing content of 2,4-dichloroaniline (2,4-DCA) up to 85% of this compound (0.1 1-1) was degraded by microbial activity as indicated by chloride release.