11
Chapter 2
Characteristics of Predominant
Microorganisms in Food
introduction
The microbial groups important in foods consist of several species and types of bacteria, yeasts,
molds, and viruses. Although some algae and protozoa as well as some worms (such as nematodes)
are important in foods, they are not included among the microbial groups in this chapter. Some
of the protozoa and worms associated with health hazards, and several algae (fish and shellfish
poisoning) associated with health hazards and bioprocessing (sources of vitamins, single-cell proteins), are discussed in Chapters 17 and 28.
Bacteria, yeasts, molds, and viruses are important in food for their ability to cause foodborne
diseases and food spoilage and to produce food and food ingredients. Many bacterial species and
some molds and viruses, but not yeasts, are able to cause foodborne diseases. Most bacteria, molds,
and yeasts, because of their ability to grow in foods (viruses cannot grow in foods), can potentially
cause food spoilage. Several species of bacteria, molds, and yeasts are considered safe or food
grade, or both, and are used to produce fermented foods and food ingredients. Among the four
major groups, bacteria constitute the largest group. Because of their ubiquitous presence and rapid
growth rate, even under conditions in which yeasts and molds cannot grow, they are considered
the most important in food spoilage and foodborne diseases.
Prion or proteinaceous infectious particles have been identified as causing transmissible spongiform encephalopathies (TSEs) in humans and animals (see Chapter 28). However, their ability
to cause foodborne diseases is not clearly understood.
In this chapter, a brief discussion is included initially on the methods currently used in the
classification and nomenclature of microorganisms and later on the important characteristics of
microorganisms predominant in food.
Chapter 2
Characteristics of Predominant
Microorganisms in Food
introduction
The microbial groups important in foods consist of several species and types of bacteria, yeasts,
molds, and viruses. Although some algae and protozoa as well as some worms (such as nematodes)
are important in foods, they are not included among the microbial groups in this chapter. Some
of the protozoa and worms associated with health hazards, and several algae (fish and shellfish
poisoning) associated with health hazards and bioprocessing (sources of vitamins, single-cell proteins), are discussed in Chapters 17 and 28.
Bacteria, yeasts, molds, and viruses are important in food for their ability to cause foodborne
diseases and food spoilage and to produce food and food ingredients. Many bacterial species and
some molds and viruses, but not yeasts, are able to cause foodborne diseases. Most bacteria, molds,
and yeasts, because of their ability to grow in foods (viruses cannot grow in foods), can potentially
cause food spoilage. Several species of bacteria, molds, and yeasts are considered safe or food
grade, or both, and are used to produce fermented foods and food ingredients. Among the four
major groups, bacteria constitute the largest group. Because of their ubiquitous presence and rapid
growth rate, even under conditions in which yeasts and molds cannot grow, they are considered
the most important in food spoilage and foodborne diseases.
Prion or proteinaceous infectious particles have been identified as causing transmissible spongiform encephalopathies (TSEs) in humans and animals (see Chapter 28). However, their ability
to cause foodborne diseases is not clearly understood.
In this chapter, a brief discussion is included initially on the methods currently used in the
classification and nomenclature of microorganisms and later on the important characteristics of
microorganisms predominant in food.