Distribution and Catabolic Diversity of 3-Chlorobenzoic Acid Degrading Bacteria Isolated from Geographically Separated Pristine Soils.
Abstract
Chlorinated aromatic compounds have been used extensively in industry and agriculture. Even though chloroaromatic compounds are generally viewed as xenobiotic, numerous bacteria have been isolated that are able to mineralize these compounds. However, it is not known whether these isolates have recently evolved new catabolic traits or if they are genetically preadapted for xenobiotic degradation. In this study, 3-chlorobenzoic acid (3-CBA) was chosen as a model substrate to test the hypothesis that natural bacterial populations are preadapted for xenobiotic degradation. Pristine soils were sampled to determine if isolates could be cultivated without long-term enrichment. Two ecosystems were selected: (1) Mediterranean, selerophyllous woodlands in California, Chile, South Africa, and Australia; and (2) boreal forests in Canada and Russia. A two-step enrichment protocol using 3-CBA-UL-ring-14C was used to detect mineralization in mixed communities. Isolates were obtained by plating on R2A agar. In all 610 3-CBA degrading isolates were cultured from these sites indicating that the distribution of 3-CBA catabolic activity is widespread in pristine soil ecosystems. Catabolic activity of individual strains was assessed by HPLC analysis. Population structures of 3-CBA degraders were compared by rank ordering the percent transformation in these incubations. The variation in the ability of different strains to transform 3-CBA is attributed to natural variation in the specificity of catabolic enzymes. To determine if variability was present in other enzymes, genotypically distinct strains were examined for their catabolic versatility using other substituted aromatic compounds and a novel (33)S incorporation assay. The data reveal appreciable diversity in the range of other metabolizable compounds.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1996
- Accession Number
- ADA306000
Entities
People
- Albert N. Rhodes
Organizations
- Armstrong Laboratory