Influence of culture media on the radiation resistance of Micrococcus radiodurans.
The addition of NZ-case (a tryptic digest of casein) to a growth medium (PC) consisting of tryptone, glucose, and yeast extract caused a significant decrease in gamma radiation resistance of Micrococcus radiodurans. The level of radiation resistance was inversely related to the concentration of NZ-case. The ld(50) for this organism was approximately 700 krad when grown in tryptone, glucose, yeast extract, and dl-methionine (TGYM) broth, but it was approximately one-half as resistant when grown in a PC medium containing 0.5% NZ-case (PCNZ). The resistance to ultraviolet light was also reduced. Cultures transferred from PCNZ to TGYM media regained the high level of resistance.
D002364:Caseins / Q000494:pharmacology*; D003470:Culture Media; D004269:DNA, Bacterial / Q000032:analysis; D008837:Micrococcus / Q000032:analysis / Q000528:radiation effects*; D008858:Microscopy, Phase-Contrast; D012329:RNA, Bacterial / Q000032:analysis; D011830:Radiation Effects; D014466:Ultraviolet Rays
D002364:Caseins; D003470:Culture Media; D004269:DNA, Bacterial; D012329:RNA, Bacterial