Deck 26: Applied Microbiology

Question 1

Approximately 50% of the foodborne outbreaks in restau rants that were associated with poultry were caused by:
(a) Salmonella spp.
(b) Clostridium perfringens
(c) Staphylococcus aureus
(d) Escherichia coli
(e) Pseudomonas mephitica

Answer 1

Microorganisms inhabit the body surfaces and the gut of animals. Hence, they are likely to be found in the meat.
Improper handling and storage can lead to the spoilage of meat as well as the transmission of pathogens through meat. This may lead to various foodborne illnesses.
Improper handling of poultry in restaurants has been reported to cause cases of foodborne infections. About half of these cases have been reported due to Salmonella species. A smaller percentage has been due to Clostridium perfringens and Staphylococcus aureus.
Escherichia coli can contaminate milk and give it a fecal odor.
Pseudomonas mephitica can spoil refrigerated meat under low oxygen concentration. It produces hydrogen sulfide that can react with myoglobin of meat to produce green discoloration.
Hence, the correct option is (a) Salmonella species.

Question 2

Which of the following compounds can be made by the ac tion of microorganisms?
(a) Ethanol
(b) Acetone
(c) Butanol
(d) Glycerol
(e) All of these

Answer 2

The fermentative ability of microorganisms can be used for the production of valuable products, some of which include organic acids, alcohols, amino acids, vitamins, and antibiotics.
Ethanol is an important industrial solvent that can be produced by the fermentation of sugars by yeasts such a Saccharomyces cerevisiae.
Thermophilic species of Clostridium have been used for the production of ethanol rapidly from cellulosic waste. The bacterium Zymomonas mobilis is used for the production of large quantities of ethanol.
Acetone and butanol can be produced by acetone-butanol fermentation by Clostridium acetobutylicum by using starch.
Glycerol can be produced by the modification of ethanol fermentation by yeasts such as Saccharomyces cerevisiae. The addition of sodium sulfite can divert the fermentation from ethanol production to glycerol production.
As all the stated products can be produced by different microbial species, the correct option is (e) all of these.

Question 3

Hens may lay infected eggs if they are infected with:
(a) Clostridium perfringens
(b) Staphylococcus aureus
(c) Escherichia coli
(d) Pseudomonas mephitica
(e) Salmonella enterica (biovar pullorum)

Answer 3

Hens may lay infected eggs due to Salmonella enterica (biovar pullorum ) infection. The organisms survive on the egg shells and enter the broken egg to multiply and cause infections.
Hence, the option (e) is correct.
Clostridium perfringens is found on dressed poultry products due to mishandling and account for food borne infections.
Hence, option (a) is incorrect.
Staphylococcus aureus cannot enter egg after the egg is fertilized.
Hence, the option (b) is incorrect.
E.coli is generally not associated with poultry.
Hence, the option (c) is incorrect.
Pseudomonas mephitica grows on meats, even when they are refrigerated. It produces foul smell and green discoloration. It is not associated with poultry.
Hence, the option (d) is incorrect.

Question 4

Which of the following are not used as a food source?
(a) Basidiomycete fungi
(b) Yeast
(c) Algae
(d) Cyanobacteria
(e) Enteric bacteria

Question 5

Freshly prepared cantaloupes are more prone to bacterial contamination than other vegetables because:
(a) They rot more quickly
(b) Bacteria persist beneath the shell
(c) Their netted surfaces become contaminated and are difficult to sanitize
(d) It takes longer to get them from farms to markets
(e) Bacteria are used to ripen them

Question 6

What modifications can be made to microbial metabolic processes in order for them to produce desirable products in amounts that are commercially profitable?
(a) Modify organisms by genetic engineering
(b) Alter environmental conditions
(c) Alter nutrients available to microbes
(d) Isolate mutants that produce large amounts of useful products
(e) All of the above

Question 7

What is it about clams that make them especially likely sources of human infection?
(a) They have sticky interiors that make microorganism at tachments easy.
(b) Their ability to glow with Photobacterium phosphor eum attracts pathogenic species of microorganisms.
(c) They are best eaten raw.
(d) They are filter feeders, obtaining food by filtering water and extracting microbes.
(e) Their hard outer shell seals in and concentrates any contaminating microbes.

Question 8

What organisms are most likely to contaminate milk?

Question 9

Match the following microorganisms that can be found inmilk to their descriptions:

Question 10

What dangers does honey present?

Question 11

Why do foods high in sugar concentration (jellies, jams, can dies, candied fruits) resist microbial contamination?
(a) Microbes do not have the necessary enzymes to break down the sugars.
(b) High sugar concentrations create sufficient osmotic pressure that inhibits microbial growth.
(c) Microbes prefer foods low in sugar.
(d) Both a and b.
(e) Both b and c.

Question 12

What is bone stink?

Question 13

Match the following conditions to the most likely microbial cause:

Question 14

What pathogenic bacteria are associated with eggs?

Question 15

Which of the following methods still in use today were de veloped by early civilizations to preserve food?
(a) Canning
(b) Drying
(c) Acidic conditions
(d) Lyophilization
(e) b and c

Question 16

What is flat sour spoilage?

Question 17

In contrast to nonionizing, the use of ionizing radiation (such as gamma rays) to preserve food is discouraged because it can make food radioactive. True or false?

Question 18

How does thawing frozen foods make them more susceptible to microbial food spoilage?

Question 19

Which of the following is NOT a method of food preservation?
(a) Repeated cycles of freezing and thawing
(b) Drying
(c) Canning with moist heat under pressure
(d) Lyophilization
(e) Salting foods

Question 20

Why are there different methods of pasteurization?

Question 21

A young married student became pregnant. Her husband told her that fatherhood was not for him, and he ran off, never to be located again. Finances were hard for the young mother try ing to work, finish college, and take care of her baby. She lived out in the country, and on her drive to school she passed a chicken farm that advertised ''Pet Eggs'' for sale, very cheaply. These were cracked eggs. In an effort to save money, she bought some, scrambled them, and fed them to her young son. He be came very ill, nearly died, and survived only to be profoundly retarded for the rest of his life. How did this happen? What was the diagnosis? Would you buy those eggs for your pet? Unfortunately, this is a true story.

Question 22

Match the following chemical additives for food preserva tion to their uses or mode of action:

Question 23

Describe the process of cheese production.

Question 24

Suppose that your microbiology class is going to have a party where everything consumed is produced by microorganisms. What are some items you could take?

Question 25

Match the following products with their method of production:

Question 26

What are the origins and use of single-cell protein?

Question 27

Fruits and vegetables are both subjected to bacterial and fungal soft rot. How do plants protect themselves from this oc currence?
(a) They emit a low-pitched sonar wave to disrupt attach ment of microbes.
(b) They release antimicrobial substances.
(c) The skins of plant foods contain protective waxes.
(d) All of the above.
(e) Both b and c.

Question 28

Spirulina spp. have been used as a source of food. These mi croorganisms are a type of:
(a) Cyanobacterium
(b) Yeast
(c) Fungus
(d) Alga
(e) None of these

Question 29

List several enzymes and amino acids that are produced by industrial microbiology methods.

Question 30

Industrial microbiology today has been a huge success in providing us (the consumer) with hundreds of different substmade with the use of microorganisms. However, industrial microbiology has not been without its problems. What are some of the difficulties this industry has had to overcome to be successful?

Question 31

Which of the following microorganisms can be added to milk to make a cultured dairy product?
(a) Streptococcus lactis
(b) Streptococcus cremoris
(c) Leuconostoc citrovorum
(d) Lactobacillus bulgaricus
(e) All of these

Question 32

How do microbes help in mining and in waste disposal?

Question 33

A green discoloration on refrigerated meat may be caused by the growth of:
(a) Pseudomonas syringae
(b) Monilia sitophila
(c) Rhizopus nigricans
(d) Pseudomonas mephitica
(e) Pseudomonas fluorescens

Question 34

What happens to curd during the process of cheese ripening?
(a) Microorganisms carry out anabolic reactions.
(b) Microorganisms oxidize glucose, assemble new poly peptide chains, and make fatty acids.
(c) Microorganisms make alkaline products from the curd, giving the cheese its flavor.
(d) Microorganisms ferment lactose and decompose curd by catabolizing proteins and fatty acids to form acids and their oxidation products that flavor the cheese.
(e) None of the above.

Question 35

What are the safeguards one can take to protect against Salmonella-contaminated poultry, eggs, and meats?

Question 36

Lactobacillus planetarum and Pediococcus cerevisiae are two microorganisms that ferment heterolactic acid, which aids in this food's preservation and tangy flavor:
(a) Tofu
(b) Pickles
(c) Cold cuts (salami, summer sausage, and Lebanon bologna)
(d) Sauerkraut
(e) Vinegar