The viable but non-culturable hypothesis and medical bacteriology

Barer, Michael R.; Gribbon, L. T.; Harwood, Colin R.; Nwoguh, C. E.

doi:10.1097/00013542-199310000-00001

Cited by 134 publications

(109 citation statements)

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“…1). Similar results from other studies have been interpreted as indications that nonculturable cells were still viable and thus in the VBNC state (Barer et al 1993, Oliver 1993. The VBNC state is a particular condition that bacteria may undergo when environmental conditions are not suitable for normal cell growth and division.…”

Section: Discussionsupporting

confidence: 82%

Resuscitation of Seventeen-year Stressed Salmonella typhimurium

Dhiaf¹,

Bakhrouf²

2008

Oceanological and Hydrobiological Studies

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Salmonella enterica serovar typhimurium was stressed by incubation in seawater microcosms for seventeen years. The microcosms were prepared in such a way as to allow progressive evaporation of the water. Despite being introduced into the sterile seawater at very high concentrations, the Salmonella rapidly declined to levels undetectable by plate counts on nutrient agar. After two years of starvation, about half of the seawater volume had evaporated from each microcosm, and salt crystals appeared. Inoculation of the salty suspension did not result in any culturable strains in selective and non-selective media. However, incubation of samples in nutrient-rich broth, without supplemental growth factors, allowed resuscitation of stressed cells, yielding colonies that remained viable for extended periods of time. After three years the total volume of water had evaporated from each microcosm, and only salt crystals remained. These microcosms were then incubated at room temperature for seventeen years. Resuscitation of VBNC Salmonella from the salt crystals was conducted in vitro and in vivo; recovery occurring after incubation in both nutrient broth and in mice. Recovery occurred in the Salmonella

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Section: Discussionsupporting

confidence: 82%

Resuscitation of Seventeen-year Stressed Salmonella typhimurium

Dhiaf¹,

Bakhrouf²

2008

Oceanological and Hydrobiological Studies

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“…Loss of culturability may occur if the stress encountered is too severe, or if bacteria are simultaneously subjected to a combination of several different stresses or even as a result of prolonged exposure to conditions that are not ideal for survival. It is clear that cells with an NC phenotype could be of some considerable medical or microbiological significance if they are able to resuscitate to form normal, viable organisms (Barer, 1997;Barer & Harwood, 1999;Barer et al, 1993Barer et al, , 1998Kaprelyants & Kell, 1996;Kaprelyants et al, 1999;Kell et al, 1998Kell et al, , 2003Mukamolova et al, 2003). In this study, we resuscitated NC bacteria in an appropriate medium in the presence of supernatant taken from a bacterial culture in exponential phase.…”

Section: Discussionmentioning

confidence: 95%

Formation of ‘non-culturable’ cells of Mycobacterium smegmatis in stationary phase in response to growth under suboptimal conditions and their Rpf-mediated resuscitation

et al. 2004

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Conditions were investigated that promote the formation of 'non-culturable' (NC) cells of Mycobacterium (Myc.) smegmatis in stationary phase. After cultivation in a rich medium, or under conditions that may be considered optimal for bacterial growth, or starvation for carbon, nitrogen or phosphorus, bacteria failed to enter a NC state. However, when grown under suboptimal conditions, resulting in a reduced growth rate or maximal cell concentration (e.g. in modified Hartman's-de Bont medium), bacteria adopted a stable NC state after 3-4 days incubation in stationary phase. Such conditions are not specific as purF and devR mutants of Myc. smegmatis also showed (transient) loss of culturability following growth to stationary phase in an optimized medium, but under oxygen-limited conditions. The behaviour of the same mutants in oxygen-sufficient but nutrient-inappropriate medium (modified Hartman's-de Bont medium) was similar to that of the wild-type (adoption of a stable NC state). It is hypothesized that adoption of a NC state may represent an adaptive response of the bacteria, grown under conditions when their metabolism is significantly compromised due to the simultaneous action of several factors, such as usage of inappropriate nutrients or low oxygen availability or impairment of a particular metabolic pathway. NC cells of wild-type Myc. smegmatis resume growth when transferred to a suitable resuscitation medium. Significantly, resuscitation was observed when either recombinant Rpf protein or supernatant derived from a growing bacterial culture was incorporated into the resuscitation medium. Moreover, co-culture with Micrococcus (Mcc.) luteus cells (producing and secreting Rpf) also permitted resuscitation. Isogenic strains of Myc. smegmatis harbouring plasmids containing the Mcc. luteus rpf gene also adopt a similar NC state after growth to stationary phase in modified Hartman's-de Bont medium. However, in contrast to the behaviour noted above, these strains resuscitated spontaneously when transferred to the resuscitation medium, presumably because they are able to resume endogenous synthesis of Mcc. luteus Rpf. Resuscitation was not observed in the control strain harbouring a plasmid lacking Mcc. luteus rpf. In contrast to wild-type, the NC cells of purF and devR mutants obtained under oxygen-limited conditions resuscitate spontaneously, presumably because the heterogeneous population contains some residual viable cells that continue to make Rpf-like proteins.

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“…On the other hand, the terminology for the VBNC state remains a source of debate [4]. It should always be made with reference to the method used which, as we have previously indicated, is actually based on the presence of cellular activity in cells which have lost their ability to be cultured.…”

Section: Discussionmentioning

confidence: 99%

Responses of enteric bacteria to environmental stresses in seawater

et al. 1998

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-The effects of different environmental factors (nutrient deprivation, hyperosmotic shock, exposure to light) on enteric bacteria which have been transferred into the marine environment, have been studied experimentally (microcosms) by considering demographic, physiological and genetic responses in Escherichia coli or Salmonella typhimurium populations. Short-term experiments (I 48 h) showed that nutrient deprivation induced limited changes in measured bacteriological variables, but when combined with hyperosmotic shock, it results in an energy charge decrease and inactivation of membrane transport. Light exposure mainly affects the colony-forming capacity of bacterial populations. Combining different stress factors confirmed the rapid appearance of a viable, but nonculturable state (VBNC) in populations of E. coli and S. typhimurium.It has been shown that cellular forms other than those previously described in the literature can be generated following incubation in seawater. It was also established that pre-adaptation phenomena may occur, leading to better survival (e.g. pre-incubation in seawater in darkness enhanced survival under light exposure). An explanation concerning these phenomena can be found by looking at the rpoS gene which controls the expression of numerous genes and can trigger a general anti-stress response under different adverse conditions. Although the results provide better comprehension of the fate of enteric bacteria in the marine environment, they also raise numerous questions related to fundamental and applied problems, given in the conclusion of this paper. 0 Elsevier, Paris enteric bacteria / seawater / physiology / cellular states / genetics Resume -RCponses des batteries d'origine enterique aux stress environnementaux en milieu marin. Les effets de differents facteurs environnementaux (carence nutritive, choc hyperosmotique, exposition & la lumiere) auxquels sont confrontees les batteries enteriques rejetees dans le milieu marin ont CtC etudies exptrimentalement (microcosmes) en considerant les reponses demographiques, physiologiques et genetiques des populations d'Escherichia coli ou de Salmonella typhimurium.A court terme (I 48 h), la settle carence nutritive induit des modifications limitees des variables mesurees alors que, combinee au choc hyperosmotique, elle aboutit notamment 2i une diminution de la charge energetique et a l'inactivation des transports membranaires. L'exposition B la lumiere contribue surtout a une t&s forte inhibition de la capacite a former des colonies des populations bacttriennes. La combinaison des differents stress a confirme l'apparition rapide d'un Ctat viable non cultivable dans les populations bacteriennes de E. coli et S. typhimurium.11 a Cte montre que des ttats cellulaires, autres que ceux precedemment decrits dans la litterature. peuvent &tre engendres au tours de l'incubation dans I'eau de mer. 11 s'est avert+ Cgalement que des phenomenes de preadaptation peuvent se produire et conduire a une amelioration de la survie (e.g., une incuba...

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The viable but non-culturable hypothesis and medical bacteriology

Cited by 134 publications

References 0 publications

Resuscitation of Seventeen-year Stressed Salmonella typhimurium

Resuscitation of Seventeen-year Stressed Salmonella typhimurium

Formation of ‘non-culturable’ cells of Mycobacterium smegmatis in stationary phase in response to growth under suboptimal conditions and their Rpf-mediated resuscitation

Responses of enteric bacteria to environmental stresses in seawater

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