Viable but nonculturable

Viable but nonculturable (VBNC) bacteria refers as to bacteria that are in a state of very low metabolic activity and do not divide, but are alive and have the ability to become culturable once resuscitated.^[1]

Thumb — Transmission electron micrographs of actively growing (panel A) and nonculturable (panel B) *Yersinia pestis*. Bar equals 0.5 microns.

Bacteria in a VBNC state cannot grow on standard growth media, though flow cytometry can measure the viability of the bacteria.^[1] Bacteria can enter the VBNC state as a response to stress, due to adverse nutrient, temperature, osmotic, oxygen, and light conditions.^[1] The cells that are in the VBNC state are morphologically smaller, and demonstrate reduced nutrient transport, rate of respiration, and synthesis of macromolecules.^[1] Sometimes, VBNC bacteria can remain in that state for over a year.^[1] It has been shown that numerous pathogens and non-pathogens can enter the VBNC state, which therefore has significant implications in pathogenesis, bioremediation, and other branches of microbiology.^[1]

The existence of the VBNC state is controversial. The validity and interpretation of the assays to determine the VBNC state have been questioned.^[2]

[1]

[2]

Viable but nonculturable

VBNC pathogens

References

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