This document discusses viable but non-culturable (VBNC) bacteria. VBNC bacteria are metabolically active but cannot be cultured on standard media. They enter a dormant VBNC state in response to harsh environmental conditions like nutrient starvation, temperature changes, or osmotic stress. While dormant, VBNC bacteria have low metabolic activity but maintain cell integrity and can regain culturability if conditions improve. The document outlines the characteristics of VBNC bacteria and methods to detect them, such as microscopy, gene probes, and resuscitation of dormant cells in more favorable conditions.

1. VIABLE BUT
NON-CULTURABLE
(VBNC) BACTERIA
KAPIL MOHAN GUPTA-4507 ; B.SC (HONS.) MICROBIOLOGY ;
IST SEMESTER​

2. CONTENT
2
VIABLE
BUT
NON-
CULTURABLE
• Introduction
• What is the VBNC state
?
• Charaterstics of VBNC
State
• Condition Stimulating
VBNC state
• Methods for Detection of
VBNC state
• References

3. INTRODUCTION
VIABLE
BUT
NON-
CULTURABLE
3
• The metabolically active cells that can't be
cultured on specific media are viable but non-
culturable cells (VBNC).
• Microorganisms that do not grow in culture
methods, but are still metabolically active and
capable of causing infections in animals and
plants are said to be in a VBNC state.
• VBNC will not resume growth immediately when
appropriate nutrients and conditions are provided.
• VBNC cells of Vibrio cholera, enteropathogenic
E.coli, Legionella pnuemophila, and various other
bacteria have been shown to regain culturability
after they have entered the intestinal tracts of
animals.

4. WHAT IS THE VBNC STATE ?
THE VBNC STATE IS DEFINED AS A STATE OF DORMANCY
TRIGGERED BY ENVIRONMENTAL HARSH CONDITIONS, SUCH
AS NUTRIENT STARVATION, TEMPERATURE, OSMOTIC STRESS,
OXYGEN AVAILABILITY, SEVERAL FOOD PRESERVATIONS,
HEAVY METALS, EXPLORE TO WHITE LIGHT AND DETERMINING
PROCESSES, SUCH AS PASTEURIZATION OF MILK AND
CHLORINATION OF WASTEWATER

5. CHARACTERSTICS OF VBNC
STATE
VIABLE
BUT
NON
CULTURABLE
5
Some of the characteristics of bacteria in the VBNC state are as follows:-
 Maintain apparent cell integrity.
 Possession of some form of measurable cellular activity.
 Possess the apparent capacity to regain culturability.
 Respond to an external stimulus by specific gene expression.
 Low metabolic activity.
 Exhibit dwarfing.
 Reduced nutrient transport.
 High ATP level and high membrane potential.
 Extensive modifications in cytoplasmic membrane fatty acid
compositions.

6. 6
VIABLE
BUT
NON
CULTURABLE
 Changes in cell wall peptidoglycan such as increasing cross
linking, increasing muropeptides bearing covalently bound
lipoprotein & shortening of average length of glycan
strands.
 Higher autolytic capability than exponentially growing cells.
 Plasmids are retained.
 Changed antibiotic sensitivity & as metabolic activity is
lower, most bacteria at VBNC state demonstrate high
antibiotic resistance.
 Changes in outer-membrane protein profile.
 Continuous gene expression.

7. 7
VIABLE
BUT
NON
CULTURABLE
CONDITIONS STIMULATING
VBNC STATE :
In the environment, bacterial cells can enter VBNC state may bedue to-
 Lack of nutrients.
 Lack of temperatures.
 High pressure.
 Sharp changes in pH or salinity.
 Damage to or lack of an essential cellular component..
 DNA damage.
 Activation of lysogenic phages or suicide genes such as sok/hak or
autolysins.
 Nutrient starvation

8. 8
VIABLE
BUT
NON
CULTURABLE
 Incubation outside the normal temperature range of growth.
 Explore Search Elevated or lower osmotic concentrations.
 Oxygen concentrations.
 Food preservatives.
 Heavy metals.
 Exposure to white light.
 Pasteurization of milk.
 Chlorination of wastewater.

9. METHODS FOR DETECTION
OF VBNC STATE
9
VIABLE
BUT
NON
CULTURABLE
 Bright-field microscopy with Nalidixic acid Fluorescent
microscopy
 Gene Probe / Oligonucleotide probe / Hybridization
 Blotting
 Fluorescent in situ hybridization (FISH)
 RT-PCR

10. 1 0
VIABLE
BUT
NON
CULTURABLE

11. 1 1
VIABLE
BUT
NON
CULTURABLE
Resuscination of VBNC Cells

12. 1 2
VIABLE
BUT
NON
CULTURABLE

13. REFERENCE
S
VIABLE
BUT
NON
CULTURABLE
1 3
Web References:
• www.ncbi.nlm.nih.gov
• www.frontiersin.org
Book References:
• Prescott’s Microbiology (Joanne M.
Willey, Kathleen M. Sandman, Dorothy
H. Wood) 11th Edition.

14. THANK YOU
KAPIL-4507
B.SC (HONS.)|MICROBIOLOGY SEMESTER-I