Premium
Neighbour restoration: A possible explanation for some “broken” survival curves of UV‐irradiated Escherichia coli K12 cells
Author(s) -
BernardoFilho M.,
Leitao A. C.,
AlcantaraGomes R.
Publication year - 1992
Publication title -
journal of basic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.58
H-Index - 54
eISSN - 1521-4028
pISSN - 0233-111X
DOI - 10.1002/jobm.3620320605
Subject(s) - irradiation , escherichia coli , cell survival , biology , survival analysis , exponential growth , phenotype , microbiology and biotechnology , gene , cell culture , biophysics , genetics , physics , quantum mechanics , nuclear physics , statistics , mathematics
Survival curves for UV irradiation of five non‐filamenting strains of E. coli K12 decrease exponentially at moderate levels of radiation but are broken at high levels of radiation. That is, it appears a change in the slope of survival curves, featuring a tail. As this phenomenon was observed with strains bearing uvrA and recA mutations it must be independent of the products of these genes. Experiments with isolated surviving colonies and synchronized cultures eliminated genetic and phenotypic heterogeneity as reasons for the tails in the survival curves. UV survival increased 10‐ to 15‐fold when UV‐irradiated cells were plated either with cells unable to grow in the plating medium or with bacterial cell‐free extracts. We suggest that factors related to the high cell densities used to obtain survival curves at high radiation levels (neighbour restoration) could be responsible for the survival increases, generating the tailed survival curves.