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Chapter 10
Microbial Stress Response
in the Food environment
introduction
Foodborne bacterial cells (and other microbes) are usually exposed to different physical and
chemical environments during production, processing, preservation, storage, transportation,
and consumption of foods as well as during microbiological quality evaluation of foods and
food ingredients by the recommended procedures. As a consequence, bacterial cells may become
stressed and manifest several types of altered characteristics. A stressed environment can be
both in the suboptimal growth range and beyond the growth range (Figure 10.1). Depending
on the nature and level of a stress, cells in a population can develop a higher level of resistance
to the same as well as several other types of stresses or suffer reversible sublethal injury or
even apparently lose culturability (the ability to multiply) in some recommended bacteriological
media and methods or lose viability (or the ability to multiply) permanently. Researchers have
used many different terminologies for these altered states of bacterial cells, some of which are
not well defined or are for the same condition or even scientifically contradictory. This has generated confusion among interested individuals and controversy among researchers. Currently,
there is a move among some scientists researching in the area of microbial stress to conduct
direct basic studies to understand the response of bacterial cells under different levels and the
nature of stresses and to develop consensus scientific opinion for suitable definitions and specific
terminologies.
In the last 50 years, three different broad terminologies have appeared in microbiology literature to describe altered characteristics of bacterial cells following exposure to some physical and
chemical stresses: sublethal injury (in the 1960s–1980s), 1–3 a viable but nonculturable (VBNC)
state (in the 1980s and 1990s), 4 and stress adaptation (in the 1990s). 5 In most publications, each
aspect has been treated as a separate and unique phenomenon. In this chapter, the three are
described separately, and then it is suggested that all three are probably related, differing only in
the degree of bacterial response following exposure to different levels of a stress. 6,7
Chapter 10
Microbial Stress Response
in the Food environment
introduction
Foodborne bacterial cells (and other microbes) are usually exposed to different physical and
chemical environments during production, processing, preservation, storage, transportation,
and consumption of foods as well as during microbiological quality evaluation of foods and
food ingredients by the recommended procedures. As a consequence, bacterial cells may become
stressed and manifest several types of altered characteristics. A stressed environment can be
both in the suboptimal growth range and beyond the growth range (Figure 10.1). Depending
on the nature and level of a stress, cells in a population can develop a higher level of resistance
to the same as well as several other types of stresses or suffer reversible sublethal injury or
even apparently lose culturability (the ability to multiply) in some recommended bacteriological
media and methods or lose viability (or the ability to multiply) permanently. Researchers have
used many different terminologies for these altered states of bacterial cells, some of which are
not well defined or are for the same condition or even scientifically contradictory. This has generated confusion among interested individuals and controversy among researchers. Currently,
there is a move among some scientists researching in the area of microbial stress to conduct
direct basic studies to understand the response of bacterial cells under different levels and the
nature of stresses and to develop consensus scientific opinion for suitable definitions and specific
terminologies.
In the last 50 years, three different broad terminologies have appeared in microbiology literature to describe altered characteristics of bacterial cells following exposure to some physical and
chemical stresses: sublethal injury (in the 1960s–1980s), 1–3 a viable but nonculturable (VBNC)
state (in the 1980s and 1990s), 4 and stress adaptation (in the 1990s). 5 In most publications, each
aspect has been treated as a separate and unique phenomenon. In this chapter, the three are
described separately, and then it is suggested that all three are probably related, differing only in
the degree of bacterial response following exposure to different levels of a stress. 6,7