Plasmid RFLP profiling and DNA homology inThermus isolated from hot springs of different geographical areas |
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Authors: | Leonilde M Moreira Milton S Da Costa Isabel Sá-Correia |
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Affiliation: | (1) Laboratório de Engenharia Bioquímica, Instituto Superior Técnico, Av. Rovisco Pais, P-1096 Lisboa Codex, Portugal Tel. +351-1-8417233; Fax +351-1-8480072, PT;(2) Departamento de Bioquímica, Universidade de Coimbra, P-3049 Coimbra Codex, Portugal, PT |
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Abstract: | Thirty-four strains belonging to various species of the genus Thermus (T. aquaticus, "T. thermophilus,"
"T. brockianus,"
T. scotoductus, and genomic species 2) isolated from hot springs of different geographical areas were examined for plasmid content and restriction
fragment length polymorphism (RFLP) of plasmid DNAs. The four strains of the numerical taxonomy cluster E of genomic species
2 did not harbor plasmid DNA. Overall examination of the HindIII-RFLP profiling of plasmid DNA showed considerable variability between and within genomic species, with the exception
of presumed clonal isolates. In spite of this heterogeneity, HindIII plasmid digests within a numerical taxonomic cluster gave a subset of restriction fragments of similar or identical length.
Strains belonging to genomic species 2 or unclassified isolates from S. Pedro do Sul that harbored plasmid DNA (7 of the 14
strains studied) exhibited strong DNA homology between plasmid regions. No homologous sequences to these plasmid regions were
found in chromosomal DNA from strains isolated from S. Pedro do Sul in which no plasmids were detected. The strains belonging
to T. scotoductus formed two plasmid DNA homology groups, as estimated by probing with a plasmid fragment that coincided with the two numerical
taxonomy clusters proposed previously. Among the other species, homology of plasmid regions was also found between some strains.
Strong homology was also found between plasmid regions from some strains of different taxonomic groups, isolated from the
same and from different sources, suggesting that these sequences are highly conserved in plasmids present in Thermus. For plasmid-containing strains, results of plasmid RFLP profiling/DNA homology appear promising for the typing of Thermus at the level of biotypes or of individual strains, namely, for monitoring the diversity and frequency of isolates from a
particular hot spring.
Received: 24 October 1994 / Accepted: 6 March 1995 |
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Keywords: | Thermus T aquaticus "T thermophilus" "T brockianus" T scotoductus Genomic species 2 Plasmid profiling Restriction fragment length polymorphism (RFLP) |
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