18 
under a specified set of conditions that directly measure its ability to 
survive. 
§11. DNA degradation during DAP-less and/or thymineless death: 
a) Thymineless death does not result in degradation of the DNA 
of the cell, contrary to findings with other K12 strains (O'nkawa, 1975). 
Perhaps this is due to the absence of a restriction-modification system, 
since DNA degradation is not observed during the thymineless death of the 
restrictionless, modificationless E. coli. C (Baker and Hewitt,' 1971). 
b) DNA degradation during thymineless DAP-less death for both 
yl776 and xl876 is only at best 50% complete by 12 hours at all cell 
densities measured (Curtiss e_t jil. , Figure 24) . 
c) Minicells containing plasmid DNA from y!876 are immune to 
thymineless death (Curtiss ert aK , p.18). 
§12. Survival in non-growth media: 
a) Both X1776 and X1876 survive as well as the parent strain 
X289 in several minimal environments including tap water and deionized 
water, within the limits of experimental error for the measurements 
(Curtiss et al, , Figures 25, 26, and 27). (The survival titers for the 
three strains were within a factor of 10 of an average of 5 logs of 
killing over a period of 8 days for a specific medium). 
b) X1776 and yl876 demonstrate no loss of viability over a 
period of two weeks at 4°C when stored in growth medium or one of the 
starvation media (BSG) (Curtiss ej; al. , p.19). 
§13. Survival during drying: 
To within experimental error, there is no difference in survival 
of y/39, x. 1776, and x?,876 during the effects of drying at room temperature 
[Appendix C — 206] 
