INDUCTION BY 5-FLUOROURACIL OF BACTERIOPHAGE DEVELOPMENT IN LYSOGENIC E. COLI K12 (LAMBDA).

Abstract

E. coli K12 ( lambda ), strain B-40, streptornycin-sensitive was grown to about 5 x 10/sup 9/ cells/ml at 37 deg C in modified Davis mineral riedium to which 0.8% glucose and 5 mg/ml vitamin-free casein hydrolysate were added. Preliminary experiments in which E. coli K12 ( lambda ) were incubated for at least 60 min in the presence of high concentrations (50-100 mu g/ml) of 5- fluorouracil (FU) or its deoxyriboside (FUDR) revealed that a burst of phage production occurred after the subsequent addition of thymine (T) or thymidine (TdR) plus uracil (U) or uridine (UR). In the presence of FU alone, an initial decrease in phage titre was found, followed within 30--60 min after the addition of TdR by a sharp rise that attained levels about 1000-fold higher in approximately 1 hr. In another experiment the addition of TdR to FU containing cultures at 90 min was followed within 1 hr by a sharp burst of phage production; the response was completely preverted when the same concentration of TdR was added at 0 min. Thus it was found that the initial step in phage induction by FU requires a period of time for the action of the analoguemore » in the absence of T or TdR. (P.C.H.)« less