Integron diversity in heavy-metal-contaminated mine tailings and inferences about integron evolution.


Journal Article

Integrons are horizontal gene transfer (HGT) systems containing elements necessary for site-specific recombination and expression of foreign DNA. The overall phylogenetic distribution of integrons and range of genes that can be transferred by integrons are unknown. This report contains an exploration of integrons in an environmental microbial community and an investigation of integron evolution. First, using culture-independent techniques, we explored the diversity of integrons and integron-transferred genes in heavy-metal-contaminated mine tailings. Using degenerate primers, we amplified integron integrase genes from the tailings. We discovered 14 previously undescribed integrase genes, including six novel gene lineages. In addition, we found 11 novel gene cassettes in this sample. One of the gene cassettes that we sequenced is similar to a gene that codes for a step in a pathway for nitroaromatic catabolism, a group of compounds associated with mining activity. This suggests that integrons may be important for gene transfer in response to selective pressures other than the presence of antibiotics. We also investigated the evolution of integrons by statistically comparing the phylogenies of 16S rRNA and integrase genes from the same organisms, using sequences from GenBank and various sequencing projects. We found significant differences between the organismal (16S rRNA) and integrase trees, and we suggest that these differences may be due to HGT.

Full Text

Cited Authors

  • Nemergut, DR; Martin, AP; Schmidt, SK

Published Date

  • February 2004

Published In

Volume / Issue

  • 70 / 2

Start / End Page

  • 1160 - 1168

PubMed ID

  • 14766601

Pubmed Central ID

  • 14766601

Electronic International Standard Serial Number (EISSN)

  • 1098-5336

International Standard Serial Number (ISSN)

  • 0099-2240

Digital Object Identifier (DOI)

  • 10.1128/aem.70.2.1160-1168.2004


  • eng