Evolution of the IncP-7 carbazole-degradative plasmid pCAR1 improves survival of its host Pseudomonas fluorescens Pf0-1 in artificial water microcosms.
Microbiology (Reading), 2011/8;157(Pt 8):2276-2286.
Shintani M[1, 2], Horisaki T[2], Yamane H[2], Ohkuma M[1], Nojiri H[2]
Affiliations
PMID: 21565929DOI: 10.1099/mic.0.049064-0
Impact factor: 2.956
Abstract
In our previous study, Pseudomonas fluorescens Pf0-1L, harbouring the IncP-7 carbazole-degradative plasmid pCAR1 : : rfp, was shown to be undetectable within 5 days post-inoculation in carbazole-contaminated artificial freshwater microcosms containing several plasmid-free bacteria in addition to Pf0-1L(pCAR1 : : rfp). Fourteen days after the inoculation, carbazole degraders become detectable. Here, we revealed that these isolates were not pCAR1 transconjugants, but Pf0-1L(pCAR1 : : rfp) mutants, based on RFLP and BOX-A1R-based repetitive extragenic palindromic-PCR (BOX-PCR) analysis. Notably, the mutants displayed more rapid initiation of carbazole degradation than the parent strain Pf0-1L(pCAR1 : : rfp). The mutants were unable to degrade anthranilate due to a 163 bp deletion in the antA gene, which was overcome by their transformation with a wild-type antABC-expressing plasmid. Quantitative RT-PCR analysis indicated that the transcriptional induction of carbazole-, anthranilate- and catechol-degradative genes was comparable in both parent and mutant strains. The deletion mutants became dominant in the artificial water microcosm. The mutation caused anthranilate to accumulate instead of catechol, a toxic compound for the parent strain, and may be beneficial to host survival in artificial microcosms.
MeSH terms
Biotransformation; Carbazoles; Carcinogens; DNA, Bacterial; Evolution, Molecular; Gene Deletion; Gene Expression Profiling; Microbial Viability; Molecular Sequence Data; Molecular Typing; Mutation; Plasmids; Polymorphism, Restriction Fragment Length; Pseudomonas fluorescens; Reverse Transcriptase Polymerase Chain Reaction; Sequence Analysis, DNA; Water Microbiology; ortho-Aminobenzoates
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