Danbara H, Yoshikawa M
Antimicrob Agents Chemother. 1975 Sep;8(3):243-50. doi: 10.1128/AAC.8.3.243.
The effect of two representative plasmids, R100 and F8-gal, on the susceptibility of Escherichia coli to kasugamycin was studied. R(+) and F(+) cells were found to be more susceptible to this antibiotic than R(-) and F(-) cells, respectively. Retransfer and curing experiments of these plasmids show that this increased susceptibility of host cells to kasugamycin was conferred by either of the plasmids. At the early stage of growth of R100(+) cells in the presence of kasugamycin, R(-) segregants overgrew the population and then they were replaced by kasugamycin-resistant mutants of the R(+) cells which became the majority cell line of the population. The former phenomenon is assumed to be due to the increased susceptibility of R100(+) cells to kasugamycin, and the latter is probably related to the finding that R100 enhances the spontaneous mutation of host cells to resistance to kasugamycin. The practical and experimental significance of these findings are discussed.
研究了两种代表性质粒R100和F8 - gal对大肠杆菌对春雷霉素敏感性的影响。发现R(+)和F(+)细胞分别比R(-)和F(-)细胞对这种抗生素更敏感。这些质粒的回传和消除实验表明,宿主细胞对春雷霉素敏感性的增加是由其中任何一种质粒赋予的。在春雷霉素存在下R100(+)细胞生长的早期阶段,R(-)分离菌在群体中过度生长,然后它们被R(+)细胞的春雷霉素抗性突变体取代,这些突变体成为群体中的主要细胞系。前一种现象被认为是由于R100(+)细胞对春雷霉素的敏感性增加,而后一种现象可能与R100增强宿主细胞对春雷霉素抗性的自发突变这一发现有关。讨论了这些发现的实际和实验意义。