DNA超螺旋
DNA旋转酶
质粒
生物
大肠杆菌
PBR322电话
DNA
微生物学
氧氟沙星
恒化器
分子生物学
细菌
生物化学
遗传学
抗生素
基因
DNA复制
环丙沙星
标识
DOI:10.1128/jb.185.17.5324-5327.2003
摘要
ABSTRACT The relationship between the survival of Escherichia coli during long-term starvation in rich medium and the supercoiling of a reporter plasmid (pBR322) has been studied. In aerated continuously shaken cultures, E. coli lost the ability to form colonies earlier in rich NaCl-free Luria-Bertani medium than in NaCl-containing medium, and the negative supercoiling of plasmid pBR322 declined more rapidly in the absence of NaCl. Addition of NaCl at the 24th hour restored both viability and negative supercoiling in proportion to the concentration of added NaCl. Addition of ofloxacin, a quinolone inhibitor of gyrase, abolished rescue by added NaCl in proportion to the ofloxacin added. This observation raises the possibility that cells had the ability to recover plasmid supercoiling even if nutrients were not available and could survive during long-term starvation in a manner linked, at least in part, to the topological state of DNA and gyrase activity.
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