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Zellteilung bei Escherichia coli CR34 unter Thyminmangelbedingungen
Author(s) -
Strohbach G.
Publication year - 1973
Publication title -
zeitschrift für allgemeine mikrobiologie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.58
H-Index - 54
eISSN - 1521-4028
pISSN - 0044-2208
DOI - 10.1002/jobm.19730130310
Subject(s) - thymine , thymidine , dna synthesis , dna , escherichia coli , starvation , cell division , nalidixic acid , dna replication , biology , biochemistry , cell , microbiology and biotechnology , gene , endocrinology
The result of the inhibition of DNA synthesis by depriving a thy − auxotroph of thymine depended on the strain used. In E. coli 15T − col 15 −(JG151) both the initiation of new cell divisions and the separation of cells in the process of division were inhibited by thymine starvation. On the other hand, in E. coli CR34 DNA synthesis and cell division continued for nearly 20 min after the removal of external supplies of thymidine. In this paper it was examined if cell divisions under conditions of thymine starvation could be explained on account of a considerable internal pool of thymine. Thymine deprivation in exponentially growing cultures of E. coli CR34 resulted in a small increase of DNA of about 10%. The cells continued to divide after removal of thymidine until the cell number had increased about 40–50%. Addition of nalidixic acid at the beginning of the thymine starvation period resulted in a further reduction of the DNA synthesis while the increase of the cell number remained about 40%. It was concluded from the results that it is not possible to explain an increase in the cell number of about 40% by an increase of DNA of only 10%. It was supposed that the cells which divided under conditions of thymine starvation were those which had completed a round of chromosome replication prior to the removal of thymidine. A working hypothesis was proposed to explain the different behaviour of E. coli 15T − and E. coli CR34 under conditions of thymine starvation.