Fundamental Food Microbiology, Third Edition - Fuad Fathir

118 FUNDAMENTAL FOOD MICROBIOLOGY
Lethal
Level of Stress
Sublethal
Suboptimum Optimum
Dead or Nonculturable in any Circumstance
Figure 9.5 Schematic representation of bacterial stress response when exposed to a physical
or chemical environment beyond optimum growth range. See text for explanations.
under any stress the level of injury increases as the level of stress increases. For
some cells, the injury can be repaired rapidly in a nonselective or a nutritionally
rich medium; these cells, usually designated as sublethally injured cells, probably
have a low level of injury. Some other cells, probably because of high level of injury,
require more exact resuscitation environment for repair; these cells probably include
VBNC cells (alternatively designated as not normally culturable or NNC cells).
Finally, some stressed cells fail to multiply under any resuscitation conditions and
are designated as lethally injured (or dead) cells.
Foodborne pathogens and spoilage bacteria can be stress adapted, sublethally
injured, or VBNC (or NNC) by the many processing, preservation, transportation,
and storage conditions used in food production. They may not be detected from a
contaminated food by many of the recommended methods used for their detection.
Effective methods have to be developed and used for their detection in food and
safeguard the health of the consumers and loss of food from spoilage.
REFERENCES
Growth Range
Sublethal Injury (Easily Repaired)
VBNC or Not Normally Culturable (NNC)
Stress Adaptation (Increased Resistance)
1. Ray, B., Ed., Injured Index and Pathogenic Bacteria, CRC Press, Boca Raton, FL,
1989.
2. Andrew, M.H.E. and Russell, A.D., Eds., The Revival of Injured Microbes, Academic
Press, Orlando, FL, 1984.
3. Hurst, A. and Nasim, A., Eds., Repairable Lesions in Microorganisms, Academic
Press, Orlando, FL, 1984.
4. Colwell, R.R. and Grimes, D.J., Eds., Nonculturable Microorganisms in the Environment,
ASM Press, Washington, D.C., 1995.
5. Yousef, A.E. and Juneja, V.K., Eds., Microbial Stress Adaptation and Food Safety,
CRC Press, Boca Raton, FL, 2003.