Open AccessAre UV‐induced nonculturable Escherichia coli K‐12 cells alive or dead?
Author(s) -
Villarino Andrea,
Rager MarieNoëlle,
Grimont Patrick A. D.,
Bouvet Odile M. M.
Publication year - 2003
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1033.2003.03652.x
Subject(s) - escherichia coli , viable but nonculturable , lysis , microbiology and biotechnology , chemistry , irradiation , pentose phosphate pathway , flux (metallurgy) , metabolism , cell culture , glycolysis , bacteria , biology , biochemistry , physics , genetics , organic chemistry , nuclear physics , gene
Cells that have lost the ability to grow in culture could be defined operationally as either alive or dead depending on the method used to determine cell viability. As a consequence, the interpretation of the state of ‘nonculturable’ cells is often ambiguous. Escherichia coli K12 cells inactivated by UV‐irradiation with a low (UV1) and a high (UV2) dose were used as a model of nonculturable cells. Cells inactivated by the UV1 dose lost ‘culturability’ but they were not lysed and maintained the capacity to respond to nutrient addition by protein synthesis and cell wall synthesis. The cells also retained both a high level of glucose transport and the capacity for metabolizing glucose. Moreover, during glucose incorporation, UV1‐treated cells showed the capacity to respond to aeration conditions modifying their metabolic flux through the Embden–Meyerhof and pentose‐phosphate pathways. However, nonculturable cells obtained by irradiation with the high UV2 dose showed several levels of metabolic imbalance and retained only residual metabolic activities. Nonculturable cells obtained by irradiation with UV1 and UV2 doses were diagnosed as active and inactive (dying) cells, respectively.