Food Microbiology Exam 1.pdf 2026//2027!!
Food Microbiology Exam 1
Study online at https://quizlet.com/_1i5a31
1. In food microbiology, what is the These bacteria are a strong indicator of pathogens, as
most important characteristic of they are found in the intestinal tract of humans.
coliforms, such as citrobacter/en-
terobacter/klebsiella/escherichia?
2. What color does a gram-negative red/pink
bacteria stain?
3. What color does a gram-positive purple, due to picking up crystal violet in the thick pepti-
bacteria stain? How? doglycan layer
4. What is an aerobe? a microbe that uses oxygen in metabolic reactions, and
requires oxygen for growth (>21%)
5. What is an anaerobe? microbe that can't use oxygen or grow in thee presence
of it i.e. clostridium botulinum
6. What is a microaerophile? a microbe that requires a small amount (~5%) of oxygen
to grow. large amounts of oxygen are toxic- these kind of
bacteria don't have that many enzymes to prohibit toxic
derivatives of oxygen consumption (i.e. hydrogen per-
oxide). i.e. campylobacter jejuni requires 85% nitrogen,
10% CO2 and 5% oxygen
7. Why are anaerobes unable to live anaerobes lack oxygen-detoxifying enzymes such as SOD
in air (oxygen)? (superoxide dismutase, which changes O2->H2O2 which
is much less toxic) and CAT (catalase, which changes
2H2o2->2H20+o2)
8. What is a facultative anaerobe? one that doesn't require oxygen but may use it if avail-
able (very metabolically versatile). these microbes can
use oxygen or other compounds as a terminal electron
acceptor i.e. salmonella or listeria
Page 1 of 11 9/15/2026, 7:27:11 AM
, Food Microbiology Exam 1.pdf 2026//2027!!
Food Microbiology Exam 1
Study online at https://quizlet.com/_1i5a31
9. What is an aerotolerant anaerobe? one that cannot use oxygen metabolically but can grow in
its presence (tolerates 21% oxygen air). these microbes
have pseudocatalase and can also excrete H2O2. i.e.
lactobacillus
10. What kind of microbial groups An anaerobic environment could host anaerobes, facul-
would grow in vacuum-packed tative anaerobes, and aerotolerant anaerobes
meat?
11. What are desirable roles of mi- Food bioprocessing (use of foodgrade microbes such as
croorganisms in food? starter cultures), fermented foods, microbial enzymes are
also used. Also, microbes are used in food biopreserva-
tion and probiotics
12. What is food biopreservation? The use of antimicrobial metabolites from desirable mi-
crobes to preserve food. This controls pathogens and
spoilage organisms
13. What are undesirable roles of mi- Food spoilage occurs through growth of undesirable mi-
croorganisms in food? crobes in food/action of microbial heat-stable enzymes.
Foodborne diseases are aplenty, especially in mass pro-
duction of food, and involve pathogenic microbes (bac-
teria, molds, viruses). The chances increase in foreign
imports due to introduction of new pathogens. More
diseases are caused by foods of animal, not plant origin.
14. What are the primary sources of 1. soil and water
foodborne microorganisms? 2. plants/plant products (LAB, pseudomonas, xan-
thomonas- both pathogens)
3. food utensils/contaminated harvest containers
4. intestinal tract of humans and animals (fecal contami-
nation of soil/water, some of which might be coming into
contact with produce) i.e. E. coli/salmonella
Page 2 of 11 9/15/2026, 7:27:11 AM
Food Microbiology Exam 1
Study online at https://quizlet.com/_1i5a31
1. In food microbiology, what is the These bacteria are a strong indicator of pathogens, as
most important characteristic of they are found in the intestinal tract of humans.
coliforms, such as citrobacter/en-
terobacter/klebsiella/escherichia?
2. What color does a gram-negative red/pink
bacteria stain?
3. What color does a gram-positive purple, due to picking up crystal violet in the thick pepti-
bacteria stain? How? doglycan layer
4. What is an aerobe? a microbe that uses oxygen in metabolic reactions, and
requires oxygen for growth (>21%)
5. What is an anaerobe? microbe that can't use oxygen or grow in thee presence
of it i.e. clostridium botulinum
6. What is a microaerophile? a microbe that requires a small amount (~5%) of oxygen
to grow. large amounts of oxygen are toxic- these kind of
bacteria don't have that many enzymes to prohibit toxic
derivatives of oxygen consumption (i.e. hydrogen per-
oxide). i.e. campylobacter jejuni requires 85% nitrogen,
10% CO2 and 5% oxygen
7. Why are anaerobes unable to live anaerobes lack oxygen-detoxifying enzymes such as SOD
in air (oxygen)? (superoxide dismutase, which changes O2->H2O2 which
is much less toxic) and CAT (catalase, which changes
2H2o2->2H20+o2)
8. What is a facultative anaerobe? one that doesn't require oxygen but may use it if avail-
able (very metabolically versatile). these microbes can
use oxygen or other compounds as a terminal electron
acceptor i.e. salmonella or listeria
Page 1 of 11 9/15/2026, 7:27:11 AM
, Food Microbiology Exam 1.pdf 2026//2027!!
Food Microbiology Exam 1
Study online at https://quizlet.com/_1i5a31
9. What is an aerotolerant anaerobe? one that cannot use oxygen metabolically but can grow in
its presence (tolerates 21% oxygen air). these microbes
have pseudocatalase and can also excrete H2O2. i.e.
lactobacillus
10. What kind of microbial groups An anaerobic environment could host anaerobes, facul-
would grow in vacuum-packed tative anaerobes, and aerotolerant anaerobes
meat?
11. What are desirable roles of mi- Food bioprocessing (use of foodgrade microbes such as
croorganisms in food? starter cultures), fermented foods, microbial enzymes are
also used. Also, microbes are used in food biopreserva-
tion and probiotics
12. What is food biopreservation? The use of antimicrobial metabolites from desirable mi-
crobes to preserve food. This controls pathogens and
spoilage organisms
13. What are undesirable roles of mi- Food spoilage occurs through growth of undesirable mi-
croorganisms in food? crobes in food/action of microbial heat-stable enzymes.
Foodborne diseases are aplenty, especially in mass pro-
duction of food, and involve pathogenic microbes (bac-
teria, molds, viruses). The chances increase in foreign
imports due to introduction of new pathogens. More
diseases are caused by foods of animal, not plant origin.
14. What are the primary sources of 1. soil and water
foodborne microorganisms? 2. plants/plant products (LAB, pseudomonas, xan-
thomonas- both pathogens)
3. food utensils/contaminated harvest containers
4. intestinal tract of humans and animals (fecal contami-
nation of soil/water, some of which might be coming into
contact with produce) i.e. E. coli/salmonella
Page 2 of 11 9/15/2026, 7:27:11 AM
