TY - JOUR
T1 - Surface growth in rod-shaped bacteria
AU - Rosenberger, R. F.
AU - Grover, N. B.
AU - Zaritsky, A.
AU - Woldringh, C. L.
PY - 1978/8/21
Y1 - 1978/8/21
N2 - Various models advanced to explaintherelationship between cell dimensions and generation time are compared for rod-shaped bacteria growing under steady-state conditions. Equations are developed for three such models based on the linear extension of surface area. The first assumes that the rate of envelope synthesis is proportional to the instantaneous number of chromosome replication forks per cell; the second, that it is inversely related to the generation time and doubles a fixed time d prior to cell division; the third, that it is constant and doubles at initiation of chromosome replication. Non-linear least-squares analysis is used to fit the theoretical expressions for mean surface area to values calculated from experimental measurements of length and width by assuming the geometry of a right circular cylinder with hemispherical polar caps. The functions describing area at birth are all discontinuous and cannot be solved by accepted techniques; they can, however, be used to test the internal consistency of each model. Model 1 is consistent only when lateral extension and septum formation are not considered as independent processes. Model 2 provides a very satisfactory fit, the best estimate for d being 49 ± 4 min. In both cases, the values of the parameters obtained are statistically indistinguishable from those predicted on the basis of a much simpler geometry: a circular cylinder with plane parallel ends. Model 3 is unsuitable and can be rejected. Sources of experimental error and some possible consequences of the simplifications used in constructing the models, are considered. A detailed comparison is made between the control of length extension proposed previously and control of envelope synthesis. The implications of the results are discussed, and a more promising way of discriminating among the remaining models is suggested.
AB - Various models advanced to explaintherelationship between cell dimensions and generation time are compared for rod-shaped bacteria growing under steady-state conditions. Equations are developed for three such models based on the linear extension of surface area. The first assumes that the rate of envelope synthesis is proportional to the instantaneous number of chromosome replication forks per cell; the second, that it is inversely related to the generation time and doubles a fixed time d prior to cell division; the third, that it is constant and doubles at initiation of chromosome replication. Non-linear least-squares analysis is used to fit the theoretical expressions for mean surface area to values calculated from experimental measurements of length and width by assuming the geometry of a right circular cylinder with hemispherical polar caps. The functions describing area at birth are all discontinuous and cannot be solved by accepted techniques; they can, however, be used to test the internal consistency of each model. Model 1 is consistent only when lateral extension and septum formation are not considered as independent processes. Model 2 provides a very satisfactory fit, the best estimate for d being 49 ± 4 min. In both cases, the values of the parameters obtained are statistically indistinguishable from those predicted on the basis of a much simpler geometry: a circular cylinder with plane parallel ends. Model 3 is unsuitable and can be rejected. Sources of experimental error and some possible consequences of the simplifications used in constructing the models, are considered. A detailed comparison is made between the control of length extension proposed previously and control of envelope synthesis. The implications of the results are discussed, and a more promising way of discriminating among the remaining models is suggested.
UR - http://www.scopus.com/inward/record.url?scp=0018182074&partnerID=8YFLogxK
U2 - 10.1016/0022-5193(78)90132-7
DO - 10.1016/0022-5193(78)90132-7
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C2 - 703343
AN - SCOPUS:0018182074
SN - 0022-5193
VL - 73
SP - 711
EP - 721
JO - Journal of Theoretical Biology
JF - Journal of Theoretical Biology
IS - 4
ER -