146 



M. J. Thornley, J. Sinai and J. Yudkin 





0; 

 o 



C 3 



I 



2 3 4 5 6 7 



Time (hours 



Fig. 3. Effect of proflavine additions at different phases of cultural 

 growth on resistance of Esch. coli 36. 



Flask 1 — Proflavine additions start in lag phase 30 min. after 



inoculation 

 Flask 2 — Proflavine additions start in lag phase 45 min. after 



inoculation 

 Flask 3 — Proflavine additions start in late logarithmic phase 5J hrs. 



after inoculation 

 Flask 4 — Proflavine additions start in late logarithmic phase 4 hrs. 



after inoculation 

 Flask 5 — Proflavine additions start in middle logarithmic phase 2| 



hrs. after inoculation 

 Flask 6— Control for flask 1 

 Flask 7 — Control for flasks 2, 3, 4, and 5 

 Flask 8 — Control for flasks 3 and 4 



Log2 of optical density and increase in resistance plotted against time 



proflavine added gradually 



# flask 5 



growth in flask 1 and 6 expressed as logg viable count 

 no proflavine added 



Time from inoculation. 



