Recent findings on the viable but nonculturable state in pathogenic bacteria

Abstract

Many bacteria, including a variety of important human pathogens, are known to respond to various environmental stresses by entry into a novel physiological state, where the cells remain viable, but are no longer culturable on standard laboratory media. On resuscitation from this 'viable but nonculturable' (VBNC) state, the cells regain culturability and the renewed ability to cause infection. It is likely that the VBNC state is a survival strategy, although several interesting alternative explanations have been suggested. This review describes the VBNC state, the various chemical and physical factors known to induce cells into this state, the cellular traits and gene expression exhibited by VBNC cells, their antibiotic resistance, retention of virulence and ability to attach and persist in the environment, and factors that have been found to allow resuscitation of VBNC cells. Along with simple reversal of the inducing stresses, a variety of interesting chemical and biological factors have been shown to allow resuscitation, including extracellular resuscitation-promoting proteins, a novel quorum-sensing system (AI-3) and interactions with amoeba. Finally, the central role of catalase in the VBNC response of some bacteria, including its genetic regulation, is described.

Temporal and Spatial Distribution Patterns of Potentially Pathogenic Vibrio spp. at Recreational Beaches of the German North Sea

“…Previous studies suggested that V. vulnificus can withdraw into the sediments and remain in a viable but non-culturable state, when environmental conditions become unfavourable [62]; however, investigations on this topic were not within the scope of this study.…”

Archaea in artificial environments: Their presence in global spacecraft clean rooms and impact on planetary protection

“…These negative results show again that the cultivation of Archaea existing in mesophilic environments still remains very difficult. At present, nothing is known about archaeal 'viable, but nonculturable' (VBNC) states, which have been reported for bacteria (Oliver, 2009), and might also affect the cultivability of Archaea. This problematic background has also been discussed previously for the bacterial diversity in clean rooms (LaDuc et al, 2004).…”

Life Stage-specific Proteomes of Legionella pneumophila Reveal a Highly Differential Abundance of Virulence-associated Dot/Icm effectors

“…Alleron et al showed by means of an 35 S-labeling approach coupled to subsequent 2D gel electrophoresis-based proteomics, that unculturable L. pneumophila obtained after disinfection with monochloramine actively synthetized proteins and they identified nine proteins which were accumulating in higher quantities in the unculturable bacteria compared with the culturable control (32). Three of those proteins, Mip, DsbA2/Com1, and L1/RplA were quantified in UNC of our study although we used long-term starvation in tap water for generation of UNC.…”

“…Bacteria in the VBNC state fail to grow on routine laboratory media on which they would normally grow, but retain insignia of life, such as intact membranes, metabolic activity, transcription, respiration, and some attributes of virulence (35). It has been shown that unculturable L. pneumophila may resuscitate to a fully virulent form by passage through an amoebal host (30,33,34,36) and therefore provide a largely undetected source of infections.…”