High-frequency interconversion of turbid and clear plaque strains of bacteriophage f1 and associated host cell death.
Under normal cultivation conditions, a mixture of turbid and clear plaques is often apparent in cultures of bacterial cells infected with filamentous bacteriophages. Beginning with a culture of wild-type filamentous phage f1, which itself produces turbid plaques, a clear plaque strain (c1) was isolated. From c1, the turbid plaque strain t1 was isolated; from t1, the clear plaque strain c2 was isolated; and from c2, the turbid plaque strain t2 was isolated. Each of these strains was generated with a frequency of approximately 1 x 10(-4). Although filamentous phages have been thought not to induce host cell death, both turbid and clear plaque strains of f1 killed host bacteria. Plating of bacterial cells 1 h after infection revealed that colonies produced by cells infected with either wild-type f1 or strain c2 were smaller than those derived from uninfected cells, and that colony formation by infected cells was reduced by 15% and 38%, respectively. The time course of bacterial growth revealed that, at 4 h after infection, the number of CFU per milliliter of culture of cells infected with wild-type f1 or with strain c2 was reduced by 27% and 95%, respectively, compared with that for uninfected cells. Microculture analysis also revealed that the percentages of nondividing cells in f1 or c2 infected were 19% and 52%, respectively, 4 h after infection with wild-type f1 or with strain c2; no such cells were detected in cultures of uninfected cells. Negative staining and electron microscopy showed that 20% and 61% of cells infected with wild-type f1 or with strain c2 were dead 4 h postinfection. Finally, although the rates of DNA synthesis were similar for infected and uninfected cells, the rates of RNA and protein synthesis were markedly reduced in infected cells.
Kuo
M Y
MY
Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, Taiwan, Republic of China.
Yang
M K
MK
Chen
W P
WP
Kuo
T T
TT
D001426:Bacterial Proteins / Q000378:metabolism; D002455:Cell Division; D003090:Coliphages / Q000502:physiology*; D004269:DNA, Bacterial / Q000378:metabolism; D004926:Escherichia coli / Q000254:growth & development* / Q000648:ultrastructure / Q000821:virology*; D012329:RNA, Bacterial / Q000378:metabolism; D010948:Viral Plaque Assay
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012329:RNA, Bacterial