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Food Microbiology Flashcards

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1
Q

A gene with reversed orientation with respect to its regulatory sequence is called?

A

Antisense gene

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2
Q

A pool of DNA segments that is likely to contain a gene of interest is called a ____?

A

Genome library

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3
Q

A transgenic organism can be defined as what?

A

An organism containing foreign DNA

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4
Q

A thermal death curve is a plot of temperature versus log of the process time. What is the slope equal to?

A

-1/z

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5
Q

Allicin is an antimicrobial compound produced in what vegetable?

A

Onions/garlic

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6
Q

An enzyme called “coagulase” is produced by this pathogen which is highly correlated with its toxin production?

A

Staphylococcus aureus

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7
Q

An initial population of 50,000 bacteria grows with a generation time of 30 minutes. About how many bacteria 3 hours later?

A

3,200,000

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8
Q

A 6D process reduces the population of the target organism by what percent?

A

99.9999%

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9
Q

Chocolate creams have been known to undergo explosions. What is responsible for this phenomenon?

A

Clostridium species cause explosions after they enter the chocolate candy through sugars, starch and other ingredients

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10
Q

Clostridium welchhii is more commonly known as what?

A

Clostridium perfringens

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11
Q

Define “transformation”

A

The process of genetic transfer where bacteria are induced to accept and incorporate into their genome foreign pieces of cell-less, isolated DNA, often in the form of a plasmid.

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12
Q

Define a food infection.

A

Ingestion of organism and then the organism invades tissues in the body

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13
Q

What are the end products of a homofermentation by lactic acid bacteria?

A

Homofermentative - glucose fermented to > 90% lactic acid

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14
Q

Define D Value

A

Time needed to inactivate 1 log cycle of a population (or a 1 decimal reduction) at a given temperature or time needed to reduce a population to 10% of the original

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15
Q

Define fecal coliforms and indicate the reason that they are often evaluated in foods.

A

Gram negative, asporogenous rods that ferment lactose to acid and gas at 44.5 to 45.5 C

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16
Q

DNA obtained by cutting and recombining DNA molecules from different sources is called?

A

rDNA (recombinant DNA)

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17
Q

DNA sequence variations that occur when a single nucleotide in the genome sequence is altered is called what?

A

Single Nucleotide Polymorphisms (SNPs)

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18
Q

During which phase of microbial growth may bacteria be most easily killed?

A

Log phase

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19
Q

Enzymes that catalyze the hydrolysis of ester linkages in triacyglycerides are called what?

A

Lipases

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20
Q

Every microbiology student knows it’s the Bible of Bacterial Taxonomy. What is it?

A

Bergey’s Manual

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21
Q

For what does BRC stand and what is it?

A

British Retail Consortium; food safety standards system

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22
Q

For what does MPN stand?

A

Most Probable Number

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23
Q

Fresh Mexican style cheese was the vehicle for an outbreak in California in 1985 in which 300 persons became ill and almost 100 of them died. What organism, found in the finished product and throughout the plant, was responsible for this outbreak?

A

Listeria monocytogenes

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24
Q

Give three sites of action for antimicrobials.

A

Cell wall; cell membrane; genetic mechanism or functions; interfering with enzyme systems; binding essential nutrients

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25
Q

Give two microorganisms responsible for scombroid poisoning (histamine) in seafood?

A

Morganella spp., especially Morganella morganii; Others include: Proteus spp., Klebsiella pneumoniae, Clostridium perfringens, Hafnia alvei

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26
Q

How does pH negatively affect microorganisms?

A

Influence availability of metallic ions; cell permeability to cations and anions; affects tRNA and protein synthesis; activities of enzyme systems; products of metabolism of microorganisms

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27
Q

How is fungi differentiated from algae and other higher plants?

A

Lack of chlorophyll

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28
Q

How many primer(s) is(are) used in a loop-mediated isothermal amplification assay?

A

4 to 6

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29
Q

How many square centimeters in a standard 9 cm Petri dish?

A

64 cm2

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30
Q

If a food processor chooses potassium sorbate over sorbic acid it would probably because it is what: less toxic, more heat stable, more water soluble, less water soluble

A

More Soluble in water than in Sorbic acid

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31
Q

If Salmonella colonies are isolated on an XLD plate, what color will the colonies likely be.

A

Red with black centers

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32
Q

In 1996 a parasite outbreak was found on strawberries in 3 US states. What was it?

A

Cyclospora cayetenensis

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33
Q

In Baird-Parker medium, what do Staphylococcus aureus colonies look like?

A

Black with a clear zone

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34
Q

In relation to HACCP, define the term hazard.

A

Anything (biological, chemical, physical) that may cause an unacceptable consumer health risk.

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35
Q

In what year was nisin discovered?

A

1928

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36
Q

Mad Cow disease is also known as BSE, which stands for what?

A

Bovine Spongiform Encelphalopathy

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37
Q

Messenger RNA is synthesized by what process?

A

Transcription

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38
Q

Name a foodborne pathogen has the greatest tolerance for low water activity?

A

Staphylococcus aureus

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39
Q

Name a foodborne pathogen that is linked to the sequela called “Reiter’s Syndrome”

A

Salmonella, Campylobacter, Shigella, Yersinia

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40
Q

Name a method to evaluate surface bacteria contamination.

A

Swab and streak SMA plate, direct contact plating

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41
Q

Name the common biological indicator for acceptable autoclave function.

A

B. stereothermophilus spores

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42
Q

Name the two crops which are clearly considered to be the major sources of dietary aflatoxin in the U.S.

A

Corn and Peanuts

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43
Q

Name the type of botulism most often associated with fish and which may grown at low temperatures?

A

Type E

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44
Q

Name three factors that contribute to the preservative action of smoking foods.

A

Temperature, drying and salt lower water activity, smoke contains antimicrobials and antioxidants

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45
Q

Name three means of genetic material exchange between bacteria?

A

Transduction, Transformation, conjugation

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46
Q

Name two conditions under which yeasts and molds will out compete most bacteria.

A

Low aw (0.6-0.7) and pH 9

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47
Q

Name two organisms responsible for pickle fermentation?

A

Lactobacillus plantarum, Pediococcus cerevisiae (these are the 2 that are most involved), Lactobacillus brevis

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48
Q

Name two species of bacteria that cause human food poisoning by producing a bacterial toxin in the food product.

A

Staphylococcus aureus, Clostridium botulinum, Bacillus cereus

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49
Q

Name two ways that freezing slows down the growth of microorganisms.

A

Lowers temperature and slows metabolic processes down and decreases water activity

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50
Q

Of the Staphylococcal enterotoxins, which type is the most frequent cause of food poisoning?

A

Type A

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51
Q

Organisms whose genetic material has been altered using genetic engineering techniques are called what?

A

Genetically Modifed Organisms or GMOs

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52
Q

Sauerkraut results from what type of fermentation process?

A

Lactic Acid

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53
Q

Structures composed of a polymer of glycerol or ribitol joined by phosphate groups and amino acids covalently linked to muramic acid in the cell walls of gram positive bacteria are called what?

A

Teichoic acids

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54
Q

The Lohman reaction is catalyzed by ATP creatine phosphotransferase. Its function is to replenish ______.

A

ATP

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55
Q

The manufacture of tempeh requires what two essential ingredients?

A

Soybeans and mold (Rhizopus oligosporus or Rhizopus oryzae)

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56
Q

The medium used for the detection of Lactic Acid Bacteria goes by the acronym MRS; what does MRS stand for?

A

deMann, Rogosa, and Sharpe

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57
Q

The oxidase test detects the presence of what enzyme?

A

Cytochrome C oxidase

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58
Q

The term hyphae refers to: A. a large pipe that carrier water; B. bacterial growth; C. mold growth; D. a packaging machine

A

mold growth

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59
Q

The toxin from Clostridium botulinum impairs nerve function by blocking release of what?

A

Acetylcholine

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60
Q

Toxoplasmosis is caused by what microorganism?

A

Toxoplasma gondii, a coccidian protozoan

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61
Q

Use of a chemical compound to reduce viable pathogenic and spoilage vegetative microorganisms on food contact surfaces or some raw food surfaces is called what?

A

Sanitization (NOTE: NOT sanitation)

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62
Q

Vibrio vulnificus food poisoning has been associated with what type of seafood product?

A

Raw oysters and clams

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63
Q

What agency is responsible for maintaining records and reporting foodborne illnesses in the US?

A

Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia

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64
Q

What antimicrobial food preservative is a macrolide antibiotic

A

natamycin

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65
Q

What are bacteriocins?

A

Proteins or protein complexes produced by bacteria with bactericidal activity directed against species closely related to the producer bacteria.

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66
Q

What are haloduric bacteria?

A

Organisms that can withstand but not grow in high concentrations of salt

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67
Q

What are halophilic bacteria?

A

Organisms that can grow in the presence of and require high concentrations of salt

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68
Q

What are hemolytic bacteria?

A

Bacteria which can lyse blood cells

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69
Q

What are osmophilic bacteria?

A

Bacteria that prefer high osmotic pressures - those that can grow in a relatively higher osmotic environment

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70
Q

What are porins?

A

Outer membranes proteins that form pores wide enough to allow passage of most small hydrophobic molecules through the cell membrane of bacteria.

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71
Q

What are some viruses that cause foodbome human illnesses?

A

Hepatitus, Rotavirus, Norwalk virus

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72
Q

What are the 2 distinct syndromes of B. cereus gastroenteritis?

A

Emetic – intoxication; Diarrheal - toxicoinfection

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73
Q

What are the general water activity limitations for bacteria, yeast, and molds (list 3 separate answers)?

A

Bacteria: 0.90 Yeasts: 0.88 Molds: 0.80 (Halophilic bacteria can go to 0.75; halophilic yeasts can go to 0.60; and halophilic molds can go to 0.65)

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74
Q

What are the two main types of bacteriophages and how do they operate?

A

Virulent phage (lyses cells); Temperate phage (inserts genetic material into bacterial cell, which then becomes a carrier)

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75
Q

What are the two methods yeast used to divide?

A

budding, binary fission

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76
Q

What are the two templates for RPCR and PCR?

A

RNA, DNA

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77
Q

What are the types of double helix DNA?

A

A, B, and Z

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78
Q

What are two components that make up the outer cell membrane of gram negative bacteria?

A

Lipopolysaccharide; porins; lipoproteins; Outer membrane proteins

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79
Q

What bacteria, usually found in powdered milk formulas, is the cause of neonatal necrotizing entercolitis?

A

Cronobacter sakazakii

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80
Q

What bacterial genus is often the cause of foodborne illness in seafood?

A

Vibrio spp.

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81
Q

What bacteriocin is produced by Pediococcus and what does it act against?

A

Pediocin

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82
Q

What bacterium causes flat sour spoilage of canned food?

A

Bacillus stearothermophilus

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83
Q

What can be described as a bacterial virus that can infect specific strains of bacteria?

A

Bacteriophage

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84
Q

What causes the “eyes” in Swiss cheese?

A

CO2 production by Propionibacterium shermanii

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85
Q

What causes the increase in pH associated with microbial spoilage of foods?

A

Deamination of amino acids, decarboxylation of organic acids

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86
Q

What company introduced CHY-MAX Chymosin and what is its significance?

A

Pfizer, Inc. introduced CHY-MAX Chymosin, the first product of rDNA technology in the US food supply.

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87
Q

What concept was devised at the Massachusetts Institute of Technology in 1966 that used microorganisms as a food source?

A

Single Cell Protein (SCP)

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88
Q

What disease on wheat is casued by the fugal species of genus Puccinia?

A

Rust

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89
Q

What do the initials SDS-PAGE stand for?

A

Sodium dodecylsulfate polyacrylamide gel electrophoresis

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90
Q

What does an indicator microorganism indicate?

A

The potential presence of a pathogenic microorganism

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91
Q

What does BT corn stand for?

A

Bacillus thuringensis corn that is used to control insects. The corn expresses high levels of Bt protein to kill the insects.

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92
Q

What does CFU stand for?

A

Colony Forming Unit

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93
Q

What does E. stand for in E. coli?

A

Escherichia

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94
Q

What does ELISA Stand for?

A

Enzyme Linked Immunosorbent Assay

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95
Q

What does FAD stand for?

A

Flavin adenine dinucleotide

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96
Q

What does IMVIC stand for?

A

I=Indole, M=methyl red, V=Voges-Proskauer, C=Citrate - Set of biochemical test used to differentiate coliforms

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97
Q

What does RAD stand for?

A

Radiation absorbed dose

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98
Q

What does RODAC stand for and describe the method

A

Replicate organism direct agar count

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99
Q

What does the operator of an operon react with?

A

A repressor protein

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100
Q

What does the term RT-PCR stand for?

A

Reverse transcriptase polymerase chain reaction

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101
Q

What Eh range favors anaerobes?

A

Anaerobes require negative Eh values (reduced)

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102
Q

What equation is used to describe the growth of microorganisms?

A

Gompertz

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103
Q

What essential oil component in oregano is a naturally occurring antimicrobial?

A

carvacrol

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104
Q

What foodborne pathogen can cause symptoms similar to appendicitis?

A

Yersinia enterocolitica

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105
Q

What forms the basis of the difference between coliforms and fecal coliforms?

A

Coliforms ferment lactose at 35 C, while fecal coliforms ferment lactose at 44.5 C.

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106
Q

What genus of microorganisms is most often involved with spoilage of refrigerated fresh meat, poultry, fish, and eggs?

A

Pseudomonas

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107
Q

What gram-negative foodborne pathogen has been linked to the syndrome known as Guillain-Barre syndrome?

A

Campylobacter jejuni

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108
Q

What group of microorganisms has an optimum growth temperature range of 10 to 15C?

A

Psychrophiles

109
Q

What group of microorganisms has an optimum growth temperature range of 20 to 30C?

A

Psychrotrophs

110
Q

What group of microorganisms has an optimum growth temperature range of 20 to 45C?

A

Mesophiles

111
Q

What group of microorganisms has an optimum growth temperature range of 55 to 65C?

A

Thermophiles

112
Q

What is a chimera?

A

Chimera is a recombinant DNA molecule made up of DNA fragments from more than 1 organism, named after the mythological beast.

113
Q

What is a Roentgen?

A

A unit of measure used for expressing exposure dose of X-ray or gamma radiation.

114
Q

What is Agrobacterium tumefaciens used for?

A

It is a tumor inducing plasmid used to transfer genes into plant genomes.

115
Q

What is an aerobic or facultatively anaerobic gram-negative non-sporeforming rod shaped bacteria that ferments lactose with the production of gas in 48 hr at 35°C called?

A

Coliform

116
Q

What is expressed when some restriction endonuclease are used under the wrong/non-optimal buffer conditions?

A

Star Activity

117
Q

What is mutually advantageous association of two or more organisms?

A

Symbiosis

118
Q

What is one example of a medium used for Salmonellae preenrichment?

A

Lactose broth, tryptose broth, brilliant green water, universal pre-enrichment

119
Q

What is SCP?

A

Single cell protein

120
Q

What is the causative agent of typhoid fever?

A

Salmonella Typhi

121
Q

What is the chief component of fungal cell walls and shells of insects and crustaceans?

A

Glucosamine

122
Q

What is the color of a positive Simmons Citrate Test?

A

Blue

123
Q

What is the commercial source of lysozyme for use as an antimicrobial food preservative?

A

Egg white

124
Q

What is the complementary mRNA sequence of the following DNA sequence: AGCT?

A

U-C-G-A

125
Q

What is the complimentary nucleotide sequence to A-G-C-T?

A

T-C-G-A

126
Q

What is the definition of a foodborne disease outbreak?

A

An incident in which 2 or more persons experience a similar illness after ingesting a common food and epidemiological analysis implicates the food as the source of the illness. Note: For botulism or chemical poisoning, 1 case constitutes an outbreak.

127
Q

What is the difference between a prokaryotic organism and a eukaryotic?

A

Prokaryotes - no nucleus, no mitochondria, wide variety of metabolic mechanisms

128
Q

What is the difference between bacteriostatic and bactericidal?

A

Bacteriostatic: inhibitory; Bactericidal: lethal, kills microorganism

129
Q

What is the Fight Back Program?

A

STEPS?????

130
Q

What is the first step in detection of Salmonellae in foods using the standard FDA cultural procedure?

A

Preenrichment

131
Q

What is the foodborne disease involving cats as obligatory intermediate hosts known as?

A

Toxoplasmosis

132
Q

What is the Hurdle Concept?

A

Reliance on multiple preservation processes to stop or slow growth of microorganisms in foods

133
Q

What is the indicator organism used to ensure the proper pasteurization of milk?

A

Coxiella burnetti

134
Q

What is the main source of Vibrio cholerae?

A

Shellfish

135
Q

What is the measurement of the oxygen used in the stabilization of organic matter by microorganisms over a 5-day period at 20 C called?

A

BOD - Biological Oxygen Demand

136
Q

What is the medical term or name given to the condition where bacteria are actively multiplying in the blood stream?

A

Septicemia

137
Q

What is the minimal water activity for growth for most bacteria?

A

0.90-0.91

138
Q

What is the minimal water activity for growth for most molds?

A

0.70-0.80

139
Q

What is the mold that produces aflatoxin?

A

Aspergillus flavus

140
Q

What is the most common cause of inconsistent acid development in the cheese industry?

A

Bacteriophage infection

141
Q

What is the most common matrix used for protein electrophoresis?

A

Polyacrylamide gels

142
Q

What is the most frequently reported Salmonella serotype isolated from human and non-human sources?

A

Salmonella Typhimurium

143
Q

What is the most radiation resistant pathogenic microorganism in food?

A

Clostridium botulinum

144
Q

What is the name for a secondary metabolite produced by fungi that can cause unnatural or deleterious biological changes in plants, animals, humans, or microorganisms?

A

Mycotoxin

145
Q

What is the percent RNA and protein in a ribosome?

A

70% RNA, 30% protein

146
Q

What is the primary microorganism used for the leavening of bakery products?

A

Saccharomyces cervisiae (bakers yeast)

147
Q

What is the primary physical defense of shell eggs?

A

Shell membrane

148
Q

What is the principal structural component of the bacterial cell wall?

A

Peptidoglycan

149
Q

What is the purpose of a Durham vial in a lactose broth?

A

To test for gas

150
Q

What is the range in kilograys of the sterilization treatment known as radappertization?

A

30-40 Kgy

151
Q

What is the site of protein synthesis within cells?

A

Ribosomes

152
Q

What is the source for the antimicrobial food preservative natamycin?

A

Streptomyces natalensis

153
Q

What is the source of catalase?

A

Bovine liver

154
Q

What is the temperature danger zone for holding foods?

A

40-140°F

155
Q

What is the term for diseases resulting from the invasion of living cells by fungi?

A

Mycoses

156
Q

What is the term for the noncoding section of DNA in a gene from eukaryotes?

A

Intern

157
Q

What is the term given to the time required to reduce a specific microbial population by 90% at a given temperature?

A

D value or Decimal Reduction Time

158
Q

What is the unit for dose rate in ionizing radiation preservation?

A

Kilogray (1 G = 100 rads; 1 kGy = 105 rads)

159
Q

What is the USDA temperature recommendation for cooking pork products?

A

It should attain 170 F (76.7 C).

160
Q

What is xerophilic?

A

Dry-loving (e.g., Dry loving molds)

161
Q

What is zoonosis?

A

Disease spread to humans from vertebrate animals.

162
Q

What medium is used to identify the presence of Bacillus cereus in a food?

A

MYP

163
Q

What microaerophile causes foodborne gastroenteritis?

A

Campylobacter jejuni

164
Q

What microorganism carries out the malolactic fermentation of wines?

A

Oenococcus oenos

165
Q

What microorganism causes ropiness of milk?

A

Alcaligenes viscolactis

166
Q

What microorganism causes trichinosis?

A

Nematode - Trichinella spiralis

167
Q

What microorganism initiates most natural vegetable fermentations?

A

Leuconostoc mesenteroides

168
Q

What microorganism is responsible for the “Noble Rot” of late harvest wine grapes?

A

Botrytis cineria

169
Q

What microorganisms are the public health parameters of pH 4.6 and aw of 0.85 based on?

A

pH = 4.6 is Clostridium botulinum; aw = 0.85 is Staphylococcus aureus

170
Q

What model is used to describe the non-linear inactivation of microorganisms by heat?

A

Weibull

171
Q

What mold is hypothesized to be connected with the Salem witch trials?

A

Claviceps purpea - ergot of wheat

172
Q

What mold is used in making blue cheese and Roqueforti?

A

Penicillium roquefortii

173
Q

What mold is used in making Camembert and Brie cheese?

A

Penicillium camemberti

174
Q

What neurotoxin from a bacterial foodborne pathogen may be inactivated by boiling?

A

Clostridium botulinum toxin

175
Q

What one bacteriocin is approved for food preservation in US and in what product may it be used?

A

Nisin–pasteurized process cheese spread (Nisin is produced by Lactococcus lactis)

176
Q

What organism causes anisakiasis or herring worm disease?

A

The nematode Anisakis simplex

177
Q

What organism causes ergotism, also known as St. Anthony’s Fire?

A

Claviceps purpurea; Caused by eating toxic alkaloids produced by the fungus on wheat, barley, rye, oats, and wild grasses

178
Q

What organism is a source of cellulase, glucoamylase, pectinase, and glucose oxidase?

A

Aspergillus niger

179
Q

What organism is responsible for Q fever?

A

Coxiella burnetti

180
Q

What organism is responsible for the ropiness defect?

A

Bacillus subtilus

181
Q

What organism is used to determine the nutrient bioavailabilty of some water soluble vitamins?

A

Lactobacillus plantarum

182
Q

What organism produces nisin?

A

Lactococcus lactis ssp. Lactic

183
Q

What organisms are a source of alpha amylase?

A

Aspergillus orzae, Bacillus subtilis

184
Q

What pathogenic bacteria can grow in foods with a water activity of 0.86?

A

Staphylococcus aureus

185
Q

What procedure involves the migration of charged molecules in a solution through an electric field?

A

Electrophoresis

186
Q

What purpose does the “Howard Mold Counts” serve?

A

Primarily for the purpose of monitoring molds in tomato products and processing equipment

187
Q

What regulatory approved food antimicrobial gets its name from the group of bacteria, previously called “Group N Streptococcus,” which produce this peptide?

A

Nisin

188
Q

What risk does L. monocytogenes pose to pregnant women?

A

Abortion

189
Q

What scientist won a Nobel prize for being the first to deduce the amino acid sequence of insulin, and a second Nobel for being the first to sequence DNA?

A

Fredrick Sanger - 1955

190
Q

What surveillance system in use by CDC uses standardized molecular subtyping (or “fingerprinting”) of foodborne disease-causing bacteria by pulsed-field gel electrophoresis (PFGE). To identify outbreaks?

A

Pulsenet

191
Q

What template is used when conducting RT-PCR?

A

ribonucleic acid (RNA)

192
Q

What term is given to the canned food spoilage that produces a lowered pH but no gas?

A

Flat-sour

193
Q

What term is used to describe a process in which chemical changes are brought about in an organic substrate through the action of enzymes and MO?

A

Fermentation

194
Q

What the three agents of foodborne illness cause the most cases?

A

Norwalk-like viruses, Campylobacter jejuni, and Salmonella

195
Q

What three sugars are included in a triple sugar slant?

A

Lactose, glucose, and sucrose

196
Q

What two groups were primarily involved in developing the HACCP system for food?

A

NASA, Pillsbury

197
Q

What type of gaseous environment is required for the growth of virtually all species of mold?

A

Aerobic

198
Q

What type of gene signals the presence of a DNA sequence of interest?

A

Reporter gene

199
Q

What type of microbiological medium is triple sugar iron agar? A. Differential, B. Selective, C. Selective and Differential

A

A: Differential

200
Q

What types of organisms are most likely to grow on the surface of a jar of jam?

A

Yeasts and molds

201
Q

What types of spoilage organisms are most likely to be found in vacuum packed, refrigerated meats held for several weeks?

A

Lactic acid bacteria, psychotrophs, microaerophiles

202
Q

What was the first genetically engineered whole food in the U.S. food supply?

A

The FLAVR SAVR tomato marketed by Calgene, Inc.

203
Q

What was the first recombinant DNA food additive sold in the USA?

A

Calf chymosin produced by microorganisms – first food grade enzyme made by recombinant DNA technology

204
Q

What was the name of HACCP before it was termed HACCP?

A

Failure mode effect analysis

205
Q

When mold growth occurs on a food, will the pH of that food increase or decrease and why?

A

Increase; molds use organic acid for nutrients

206
Q

When testing for C. perfringens what is the only negative test result that suggests a positive confirmation?

A

Motility

207
Q

Which bacterium promotes tooth decay?

A

Streptococcus mutans

208
Q

Which foodborne pathogens produces a heat-stable toxin?

A

Staphylococcus aureus

209
Q

Which of the following is a fermented food? a) sweet acidophilus milk b) tofu c) surimi d) miso

A

d) Miso

210
Q

Which of the following is a psychrotrophic food poisoning organism? - Campylobacter; E. coli; Salmonella; Yersinia enterocolitica

A

Yersinia enterocolitica

211
Q

Which of the following is a psychrotrophic foodborne pathogenic bacterium? A. Campylobacter B. Escherichia coli C. Salmonella D. Yersinia enterocolitica

A

D. Yersinia enterocolitica

212
Q

Which organ in the body is the primary site of action of aflatoxin?

A

The Liver

213
Q

Which taxonomic scheme has includes over 2000 serovars of Salmonella?

A

Kauffmann-White

214
Q

Who discovered lysozyme?

A

Alexander Fleming

215
Q

Who discovered the DNA structure?

A

Watson and Crick

216
Q

Who first described the “Hurdle Concept” and when?

A

Lothar Leistner - Federal Center for Meat Research Germany in 1978

217
Q

Who first investigated nisin for use as a food preservative antimicrobial?

A

Hirsch

218
Q

Why are enrichment techniques used when examining food for the presence of Salmonella?

A

Salmonella are usually present in small numbers. Enrichment allows Salmonella to grow and outcompete non-Salmonella microbes and also allows recovery of injured cells.

219
Q

Why is mercaptoethanol used in the preparation of protein samples for gel electrophoresis?

A

It is a reducing agent which dissociates the protein into subunits and reduces disulfide bonds.

220
Q

Wthin the HACCP model, how is Critical Control Point defined?

A

A step at which control can be applied and is essential to prevent or eliminate a food safety hazard or reduce it to an acceptable level.

221
Q

Order the following organic acid antimicrobials with respect to their pKa’s, from highest pKa to lowest. (Benzoic Acid, Sorbic Acid, Propionic Acid, Lactic Acid)

A

Propionic Acid, Sorbic Acid, Benzoic Acid, Lactic Acid

222
Q

Define an Intermediate Moisture (IM) Food.

A

Food preserved by lowering the Aw by solutes; Moisture levels = 15-50%, aw = 0.6 - 0.9

223
Q

Define vector and shuttle vector.

A

Vector - DNA molecule, capable of replication in a host organism, into which a gene is inserted to construct a rDNA molecule; Shuttle vector - can replicate in the cells of more than 1 organism (gram + and gram -); goes between the cloning host and target host.

224
Q

Following is a list of bacterial genera; tell whether they are gram positive or gram negative: Bacillus, Clostridium, Escherichia, Pseudomonas, Erwinia, Staphylococcus

A

Positive, Positive, Negative, Negative, Negative, Positive

225
Q

For what do the following stand?

RFLP, RAPD and PFGE

A

RFLP - Restriction Fragment Length Polymorphism
RAPD - Random Amplified Polymorphic DNA
PFGE- Pulse Field Gel Electrophoresis

226
Q

Give three examples of Intermediate Moisture (IM) Foods

A

fig newtons, marshmallows, jams, jellies, molasses, honey, syrups, semimoist pet foods

227
Q

How is vinegar made?

A

food product (cider, malt, whey and fruits that have fermentable sugars) fermented by yeast to ethyl alcohol, oxidation of the alcohol to acetic acid by Acetobacter and/or Gluconobacter.

228
Q

If the thermal death time for C. botulinum spores is 2.5 minutes at a temperature of 250 F with a Z-value of 18, what is the thermal death time at 286F?

A

0.025 min

229
Q

In what order are the gram stain reagents added?

A

Crystal violet, iodine, ethanol, safranin

230
Q

List 5 genotyping methods

A

Pulsed Field Gel Electrophoresis(PFGE); Repetitive extragenic palindromic PCR (Rep-PCR); Restriction Endonuclease analysis; Restriction Fragment Length Polymorphism(RFLP); Plasmid Profile Analysis; Ribotyping; Random Amplified Polymorphic DNA(RAPD)-Arbitrary primed PCR; Ribotyping; Sequencing

231
Q

Name 5 major causes of food deterioration.

A

1-microorganisms; 2-food enzymes; 3-insects, parasites, and rodents; 4-temperature; 5-moisture/dryness; 6-air/oxygen; 7-light; 8-time

232
Q

Name four genera of bacteria always considered as lactic acid bacteria.

A

Lactobacillus, Lactococcus, Leuconostoc, Pediococcus

233
Q

Name four molecular methods of fingerprinting foodborne organisms.

A

nucleic acid probes, polymerase chain reaction (PCR), multilocus enzyme electrophoresis, restriction enzyme analysis, random amplication of polymorphic DNA (RAPD), plused field gel electrophoresis (PFGE), restriction fragment length polymorphism (RFLP), ribotyping

234
Q

Name three factors that affect the heat resistance of microorganisms?

A

Temperature, pH, variation among strains, fat, protein, carbohydrate content, preservatives, number of cells, age of cells, growth medium

235
Q

Name two organisms used as starter cultures for Cottage cheese

A

Lactococcus lactis subsp lactis (or subsp cremoris) and Leuconostoc mesenteroides subsp cremoris

236
Q

Peptidoglycan is an important structural component of bacterial cell walls. Of what two amino sugars is it composed?

A

N-acetyl glucosamine (NAG), N-acetyl muramic acid (NAM)

237
Q

Reiter’s syndrome may be a sequalae of a primary foodborne infection. List two potential bacterial pathogens involved with the syndrome.

A

Campylobacter, Salmonella, Shigella, Yersinia

238
Q

The CAMP test is used to identify what foodborne pathogen? What does “CAMP” stand for?

A

Listeria monocytogenes; Christie, Atkins, Munch, Peterson

239
Q

The two microorganisms used as the starter culture for yogurt are what?

A

Streptococcus thermophilus, Lactobacillus bulgaricus (in 1:1 ratio)

240
Q

What are five uses of ionizing radiation in foods?

A

Inhibit sprouting, delay ripening, destroy insects and larvae, destroy parasites, eliminate pathogens, reduce the number of viable microbes, commercially sterilize foods

241
Q

What are the 4 Koch’s postulates and what do they apply to?

A

The causative microorganism must be present in every individual with the disease; The causative microorganism must be isolated and grown in pure culture; The pure culture must cause the disease when inoculated into an experimental animal; The causative microorganism must be reisolated from the experimental animal and reidentified in pure culture

242
Q

What are the names of the 3 typical radiation treatments used for foods?

A

Radappertization; Radicidation (pasteurization); Radurization (disinfestation, sanitization)

243
Q

What are the seven steps of HACCP?

A

Hazard Analysis, Identifying CCPs, Establishing Critical Limits, Monitoring CCPs, Corrective Action, Verification, Record Keeping

244
Q

What are the spore-forming foodborne pathogens?

A

Bacillus cereus, Clostridium perfringens, Clostridium botulinum

245
Q

What are the three major genera of mycotoxin producing fungi?

A

Aspergillus, Penicillium, Fusarium

246
Q

What are three intrinsic factors that affect the growth of microorganisms in food?

A

pH, aw, antimicrobial constituents, Eh, nutrient content, biological structures

247
Q

What are three methods for immobilizing enzymes?

A

Adsoption, Entrapment, Microencapsulation, Ion exchange, Cross-linking, Copolymerization, Covalent attachment

248
Q

What are three microbial inhibitors in egg white and how do they work?

A

Lysozyme - Lysis of cell wall (Gram-positive bacteria); Ovomucoid - Trypsin inhibitor; Conalbumin - Chelates metal ions, especially ferric ions–inhibits growth by extending lag phase; Avidin - Binds biotin; Ovoflavoprotein -Binds or sequesters riboflavin Also high pH

249
Q

What are two extrinsic factors that affect the growth of microorganisms in food?

A

Temperature, atomosphere, relative humidity

250
Q

What do the letters of the IMVIC test stand for?

A

Indole, methyl-red, vogues proskauer, citrate

251
Q

What is a plasmid? Name 3 methods for plasmid replication.

A

A self replicating, usually circular piece of DNA, primarily independent of the host chromosome (extrachromosomal); Replication: 1) unidirectional; 2) bidirectional; 3) rolling circle

252
Q

What is Taq polymerase and for what is it named?

A

A. It is a thermostable DNA polymerase; B. Thermus aquaticus (a bacterium)

253
Q

What is the difference between direct and indirect ELISA?

A

Indirect ELISA is used to detect or quantitate antibody; Direct or sandwich ELISA is used to detect or quantitate antigen

254
Q

What is the name of the causative agent that is thought to cause Bovine Spongiform Encephalopathy?

A

Prion

255
Q

What organisms do the following media select for and how do the colonies appear? XLD (xylose lysine deoxycholate), VRBA (violet red bile agar), EMB (Eosin methylene blue), Baird Parker, Sorbitol MacConkey

A

XLD - Salmonella and Shigella. pink colonies with or without black centers; VRBA - enterobacteriacae (coliforms), pink colonies with a halo; EMB - E. coli - metallic green; Baird Parker - black colonies with a halo; SMAC - E. coli O157:H7, colorless

256
Q

What three organisms are used to make Swiss cheese?

A

Streptoccus thermophilus and Lactobacillus bulgaricus and Propionibacterium shermanii

257
Q

Which microorganisms make the following hydrocolloids? Xanthan, Curdlan, Gellan

A

Xanthan - Xanthomonas campestris; Curdlan - Alcaligenes faecalis var. myxogenes; Gellan - Pseudomonas elodea

258
Q

What are the end products of a heterofermentation by lactic acid bacteria?

A

Heterofermentative - glucose fermented to > 50% lactic acid, 25% CO2, 25% ethanol and acetic acid

259
Q

The interval from exposure to infectious agent until the time of onset of clinical illness is called what?

A

Incubation period

260
Q

What are the known types of Hepatitis viruses? Which of them cause foodborne illness?

A

Hepatitis A, B, C, D and E. Hepatitis A and E are foodborne virus

261
Q

A substance in oradded to a ready-to-eat product that reduces or eliminates amicroorganisms, including pathogens, is defined by USDA/FSIS as what?

A

Antimicrobial agent

262
Q

What does AIB stand for and what do they do?

A

American Institute of Baking, third party food safety audits.

263
Q

What is the most common surrogate bacterium used to model the thermal resistance of Clostridium botulinum spores?

A

Clostridium sporogenes PA 3679

264
Q

Ready to eat foods containing this Gram positive nonsporeformer are considered adulterated in the United States

A

Listeria monocytogenes

265
Q

Violet Red Bile Agar and MacConkey’s Agar are examples of what type of media?

A

Selective and Differential

266
Q
  1. What is the genus of the the fungus known as the “machinery mold”; 2. for what product is it most often associated; 3. what is a microscopic test used to indicate its level of contamination
A

Geotrichum; tomatoes or tomato juice; Howard mold count

267
Q

Most foodborne pathogens of the genus Vibrio will not grow unless the growth medium contains at least 0.5-1% of what compound?

A

NaCl

268
Q

What genus and species of mold caused sickness among consumers of Chobani greek yogurt in 2013?

A

Mucor circinelloides

269
Q

What is the correct order of steps for a single PCR cycle?

A

denature, anneal , extend

► Food & Nutrition 4 (18 decks)

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