Gene transfer from a bacterium injected into an aquifer to an indigenous bacterium

Authors

  • J. Z. ZHOU,

    1. Centre For Microbial Ecology and Department of Crops and Soil Sciences, Michigan State University, East Lansing, MI 48824–1325, USA
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  • J. M. TIEDJE

    Corresponding author
    1. Centre For Microbial Ecology and Department of Crops and Soil Sciences, Michigan State University, East Lansing, MI 48824–1325, USA
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  • This paper derives from a previous collaborative field study on an aquifer on Cape Cod, MA (cf. Krumme ef al. 1994). The cooperators included Mary Lou Krumme and Daryl Dwyer of the German Biotechnology Institute, Richard L. Smith and the drilling crews of the US. Geological Survey, Suzanne M. Thiern and James M. liedje of Michigan State University, the Otis Air National Guard Base officials who granted permission and use of on-site facilities and the US Department of Energy who provided much of the project funding. Particularly important to the current study were the efforts of Drs Krumme, who led the field work, and Thiem who isolated novel strains 3CI3-1 and 3CB-2. Dr Zhou is a postdoctorate with background in theoretical ecology and molecular phylogeny. Field studies are expensive, require a wide range of expertise and facilities but are very important in providing ground truth in microbial ecology. This study was an attempt to further maximize knowledge gained from such a field study.

Fax +1 (517) 353 2917. E-mail 21394jmt@msu.edu

Abstract

Two novel 3-chlorobenzoate-degrading bacteria were previously isolated from an aquifer in which no such bacteria could be enriched prior to the introduction of the 3-chlorobenzoate-degrading strain, Pseudomonas sp. B13. To understand the origin of 3-chlorobenzoate-degrading genes in the two novel isolates, the 16S ribosomal RNA, clcD (dienelactone hydrolase) and clcA (chlorocatechol oxygenase) genes from these bacteria were amplified and sequenced. The partial 16S rRNA gene sequences and REP-PCR patterns showed that these two novel isolates were identical but differed from strain B13. Phylogenetic analyses revealed that the novel isolates were closely related to Alcaligenes eutrophus in the beta subclass of the Proteobacteria, whereas strain B13 was related to Pseudomonas aeruginosa and P. mendocina in the gamma subclass of the Proteobacteria. In contrast, the clcD and clcA gene sequences were identical on strain B13 and these two isolates, indicating that the 3-chlorobenzoate-degrading genes were transferred from strain B13 to these isolates. What cannot be established is when this transfer occurred.

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