Appl. Environ. Microbiol. doi:10.1128/AEM.01199-07
Copyright (c) 2007, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.
Mutations in the lux Operon of Natural Dark Mutants in the Genus Vibrio
Elizabeth A. O'Grady
and
Charles F. Wimpee*
Department of Biological Sciences, University of Wisconsin-Milwaukee
* To whom correspondence should be addressed. Email:
cwimpee{at}uwm.edu.
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Abstract |
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Bacterial bioluminescence can display a wide range of intensities among strains, from very bright to undetectable, and it has been shown previously that there are non-luminous vibrios that possess lux genes. In this paper, we report the isolation and characterization of completely dark natural mutants in the genus Vibrio. Screening of over 600 vibrio isolates with a luxA gene probe revealed that approximately 5% carried the luxA gene. Bioluminescence assays of the luxA positives, followed by rep-PCR fingerprinting, showed three unique genotypes that are completely dark. The dark mutants show a variety of lesions, including an insertion sequence, point mutations, and deletions. Strain BCB451 has an IS10 insertion sequence in luxA, a mutated luxE stop codon, and a truncated luxH. Strain BCB494 has a 396 bp deletion in luxC, and strain BCB440 has a frameshift in luxC. This paper represents the first molecular characterization of natural dark mutants, and the first demonstration of incomplete lux operons in natural isolates.