Viability and activity in readily culturable bacteria: a review and discussion of the practical issues.
In microbiology the terms 'viability' and 'culturability' are often equated. However, in recent years the apparently self-contradictory expression 'viable-but-nonculturable' ('VBNC') has been applied to cells with various and often poorly defined physiological attributes but which, nonetheless, could not be cultured by methods normally appropriate to the organism concerned. These attributes include apparent cell integrity, the possession of some form of measurable cellular activity and the apparent capacity to regain culturability. We review the evidence relating to putative VBNC cells and stress our view that most of the reports claiming a return to culturability have failed to exclude the regrowth of a limited number of cells which had never lost culturability. We argue that failure to differentiate clearly between use of the terms 'viability' and 'culturability' in an operational versus a conceptual sense is fuelling the current debate, and conclude with a number of proposals that are designed to help clarify the major issues involved. In particular, we suggest an alternative operational terminology that replaces 'VBNC' with expressions that are internally consistent.
Institute of Biological Sciences, University of Wales, Aberystwyth, U.K.
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Kell
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Kaprelyants
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Weichart
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Harwood
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Barer
D000818:Animals; D001419:Bacteria / Q000254:growth & development* / Q000378:metabolism; D001424:Bacterial Infections / Q000382:microbiology*; D018407:Bacterial Physiological Phenomena; D001431:Bacteriological Techniques; D015169:Colony Count, Microbial; D003470:Culture Media; D006801:Humans
D003470:Culture Media