Isolation and characterisation of plasmids from a wild-type strain of the extremely thermophilic eubacteriumThermus aquaticus

Abstract

We examined the extremely thermophilic Gram‐negative eubacterium Thermus aquaticus for the presence of plasmid DNA, and detected 5 species. The sizes were determined by electron microscopy and gel electrophoresis. The plasmids, pTA 1‐pTA 5, were of respective length: 13.5, 12.4, 11.2, 9.6 and 8.3 kb. Clones were isolated which differed in plasmid distribution. No correlation could be observed between the phenotype or growth behaviour and the presence of plasmids. The function of the plasmid structures still needs to be elucidated.