Lovett P S, Bramucci M G
J Bacteriol. 1975 Oct;124(1):484-90. doi: 10.1128/jb.124.1.484-490.1975.
Two of eighteen strains of Bacillus subtilis examined contained covalently closed circular duplex deoxyribonucleic acid (DNA) of homogeneous size and buoyant density. Strain ATCC 15841 contained about 16 copies per chromosome of plasmid pPL1, a circular DNA element having a molecular weight of about 4.7 times 10(6) and a buoyant density of 1.700. Strain ATCC 7003 contained about one to two copies per chromosome of plasmid pPL2. pPL2 had a molecular weight of about 46 times 10(6) and a buoyant density of 1.696. Strain ATCC 7003 appeared to be closely related to B. subtilis 168 by genetic, physiological, and biochemical criteria. Strain ATCC 15841 appeared to be much less closely related. B. pumilus ATCC 12140 contained two size classes of covalently closed circular duplex DNA. The plasmids pMB1 and pMB2 had molecular weights of about 6.8 times 10(6) and 5.3 times 10(6), respectively, and were present in several copies per chromosome.
在检测的18株枯草芽孢杆菌中，有两株含有大小均一、浮力密度相同的共价闭合环状双链脱氧核糖核酸（DNA）。ATCC 15841菌株每条染色体含有约16个质粒pPL1拷贝，pPL1是一种环状DNA元件，分子量约为4.7×10⁶，浮力密度为1.700。ATCC 7003菌株每条染色体含有约1至2个质粒pPL2拷贝。pPL2的分子量约为46×10⁶，浮力密度为1.696。根据遗传、生理和生化标准，ATCC 7003菌株似乎与枯草芽孢杆菌168密切相关。ATCC 15841菌株的相关性似乎要小得多。短小芽孢杆菌ATCC 12140含有两种大小类别的共价闭合环状双链DNA。质粒pMB1和pMB2的分子量分别约为6.8×10⁶和5.3×10⁶，每条染色体中有多个拷贝。
