Hishinuma F, Tanaka T, Sakaguchi K
J Gen Microbiol. 1978 Feb;104(2):193-9. doi: 10.1099/00221287-104-2-193.
Eight strains of thermophilic bacteria were examined for the presence of covalently closed circular deoxyribonucleic acid molecules by caesium chloride-ethidium bromide density gradient centrifugation. Four of the eight strains tested, Thermus flavus BS1, AT61, AT62 and Thermus thermophilus HB8 carried covalently closed circular DNA molecules. Thermus flavus BS1 haboured two species of plasmids with molecular weights of 6.1 X 10(6) and 17.0 X 10(6) as determined by electron microscopy. Thermus thermophilus HB8, T. flavus AT61 and T. flavus AT62 carried plasmids with molecular weights of 6.2 X 10(6), 6.6 X 10(6) and 6.6 X 10(6), respectively. Plasmids from T. flavus AT61 and AT62 were indistinguishable in their electrophoretic patterns in agarose or acrylamide gel after digestion with various restriction endonucleases. This is the first evidence for the presence of plasmids in extremely thermophilic bacteria, though their functions are unknown.
通过氯化铯-溴化乙锭密度梯度离心法，对8株嗜热细菌进行了共价闭合环状脱氧核糖核酸分子的检测。在检测的8株菌株中，嗜热栖热菌BS1、AT61、AT62和嗜热栖热菌HB8这4株携带共价闭合环状DNA分子。通过电子显微镜测定，嗜热栖热菌BS1含有两种分子量分别为6.1×10⁶和17.0×10⁶的质粒。嗜热栖热菌HB8、嗜热栖热菌AT61和嗜热栖热菌AT62分别携带分子量为6.2×10⁶、6.6×10⁶和6.6×10⁶的质粒。用各种限制性内切酶消化后，嗜热栖热菌AT61和AT62的质粒在琼脂糖或丙烯酰胺凝胶中的电泳图谱无法区分。这是嗜热细菌中存在质粒的首个证据，尽管其功能尚不清楚。
