The Biochemistry of Lysogeny 



41 



plateau is reached, a finding which could not be expected from a steady 

 death rate of the bacteria. 



On the other hand, there is the possibility with respect to the last 

 point that a number of bacteria, too small to be detected by our 

 counting technique, die, and their oozed-out cell contents bring the 

 optical density of the medium to its high level in the first 4 to 5 hours 



1.5 - 



| 1.0 



0.5 - 







3 



■15 6 



Hours 



10 



Fig. 2. The kinetics of the excretion of nucleic acid fragments by E. coli K 12 



W-6 on (1) methionine and (2) glucose starvation. Cell count 1:1.2X10° cells 



per ml.; 2:1.1 X 10 9 cells per ml. 



of starvation. The diminished accumulation from this time on could 

 be visualized as resulting from the adaptation of the remaining viable 

 bacteria to their debris-laden milieu, and temporary equilibrium might 

 be reached between the rate of death and the rate of scavenging. The 

 following findings rule out this possibility. The probable error of 

 viable-cell counting in our hands is less than 10%. Therefore, a num- 

 ber of bacteria, lO^c or less of the total, would, upon their death, have 

 to yield an optical density approximating the levels of curve 1 in Fig. 2. 

 Bacteria in logarithmic growth phase, at a cellular concentration of 

 1 X 10 8 per milliliter, were exposed to sonic vibration in a Raytheon 



