Molecular techniques applied to microbial taxonomy were used for the discrimination between Desulfovibrio SR-1 and Desulfovibrio africanus. Desulfovibrio SR-1 has a single polar flagellum and ferments pyruvate. D. africanus has lophotrichus flagella and pyruvate does not support its growth in sulfate-free media. The 16S rRNA gene and the ITS sequence analyses showed the same phylogenetic affiliation for both strains. The DNA sequences of the ITS region of Desulfovibrio SR-1 and D. africanus contain two transfer RNA genes (tRNAIle, tRNAAla), and they are 300 and 299 bases in length, respectively. The analysis of dsrAB sequences showed a better discrimination power than the 16S rRNA sequences in defining their phylogenetic affiliation. The 72% DNA-DNA similarity value did not conclusively resolve whether these strains should be considered as members of one species. The 62.4 mol% G+C content of Desulfovibrio SR-1 differs from the 63.1 mol% G+C of D. africanus. Significant differences in the genomic fingerprints (16S rDNA, PmeI-PFGE and BOX-PCR) between both strains were observed.
These results suggest that these strains have different genomic organization. The presence of plasmid DNA was only detected in Desulfovibrio SR-1. On the basis of distinct phenotypic and genotypic characteristics, strain Desulfovibrio SR-1 represents a novel subspecies of D. africanus .
|Advisor:||Krumholz, Lee R.|
|Commitee:||Duncan, Kathleen E., Hoefnagels, Marielle, Li, Jia, Thompson, James N.|
|School:||The University of Oklahoma|
|Department:||Department of Botany and Microbiology|
|School Location:||United States -- Oklahoma|
|Source:||DAI-B 68/12, Dissertation Abstracts International|
|Keywords:||Desulfovibrio, Plasmids, Pyruvates|
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