Recovery from N -Hydroxyurethan-Induced Death

Abstract

Bacteria (Escherichia coli) can recover from the lethal action of N-hydroxyurethan when they are incubated in drug-free liquid medium. This recovery, which is dependent upon energy metabolism, does not occur on solid medium. Recovery is accompanied by repair of the cellular deoxyribonucleic acid (DNA). A bacterial mutant deficient in DNA polymerase was extremely sensitive to the lethal action of hydroxyurethan. Data are presented which support the concept that DNA replication and DNA repair are mediated by different enzymes and that only the former process is inhibited by hydroxyurea.

Characterization of the Repair of Injury Induced by Freezing Salmonella anatum1

“…Repair in the presence of pyruvate also was inhibited by cyanide and DNP (data not presented). DNP inhibition of repair of injury has been reported by several workers (10, 13,16,21,26). Increases in the amount of phosphate or citrate repair in the presence of MgSO, could be due to Mg2+.…”

“…The ability of some of the freeze-injured cells to repair in the presence of phosphate or citrate indicates that the repair process, at least in these cells, was related to energy metabolism. Energy metabolism during repair of injury by cells that survived sublethal stresses has been reported (10,13,16,21,25). Citrate transport in many citrate-utilizing species in the Enterobacteriaceae depends upon a specific inducible permease system (9,26).…”

“…Carolina State University, Raleigh, N.C. 27607. tetraacetic acid treatment (10), N-hydroxyurethan treatment (16), X-ray radiation (14), and, possibly, air drying (28) required energy metabolism during repair. In many cases the energy synthesis possibly occurred in the form of adenosine triphosphate (ATP) synthesis by oxidative phosphorylation through the electron transport system (10,13,16,21,25).…”

“…Microbial cell injury has been induced by various sublethal stresses (10,19,20,(22)(23)(24)(25)27). When the stress was removed 'and the cells were exposed to a suitable environment, the repair of damage in these cells was observed (10,12,15,16,21,25). The nature of the injury produced by exposing the microbial cells to different environmental stresses and cell repair mechanisms have been studied.…”

Molecular mechanisms of accommodation in Escherichia coli to toxic levels of Cd2+

“…In this context, it is surprising that unaccommodated, Cd2+-stressed cells remain nonviable when plated on nutrient broth-NaCl-agar and, therefore, presumably do not undergo repair. Possibly relevant is the observation that the recovery of E. coli from the lethal action of N-hydroxyurethane, which is accompanied by the energy-dependent repair of deoxyribonucleic acid, also does not occur on solid medium (13). 108/ml.…”