Viable but Nonculturable Bacteria

Abstract

Abstract Viable but nonculturable (VBNC) bacteria are not detected using standard microbiological assays, hence environmental samples thought to lack bacteria may in fact contain large numbers of these dormant‐like cells. Though regrowth, or resuscitation, of bacteria remains the most definitive measure of the presence of VBNC cells, growth‐independent viability assays using flow cytometry combined with LIVE/DEAD staining, RT‐qPCR and microarray analysis have been developed to detect VBNC cells in environmental samples. Genes specific for the VBNC state have yet to be identified, however, several genes, including rpoS , are reported to be involved in the VBNC condition. Further elucidation of the genetic mechanism causing entry into and resuscitation from the VBNC state will likely coincide with advances in transcriptomic and proteomic technologies. Though controversial, the VBNC state can explain certain environmental microbial phenomena, such as the source of recurrent bacterial infections in plants and animals. Key Concepts: The VBNC state is thought to be a long‐term survival mechanism that initiates in response to environmental stress. A general, but not universal, acceptance of the VBNC condition exists even though the molecular mechanism involved has yet to be elucidated. Resuscitation of the VBNC state has been observed in only some species of bacteria reported to become VBNC. Several genes, including rpoS , mreB and rpf have been identified as being involved in the VBNC condition. Bacteria in the VBNC state may retain pathogenicity.