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Food-Borne Pathogens > Introduction > Flashcards

Introduction Flashcards

1
Q

Intrinsic factors

A

Factors inherent to the food (ph, water activity, nutrients)

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2
Q

Extrinsic factors

A

Factors external to the food (temp, gas, atmosphere)

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3
Q

Autotrophic

A

Carbon from CO2 through carbon fixation

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4
Q

Heterotrophic

A

Carbon from organic coompounds

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5
Q

Chemotrophic

A

Energy from chemical

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6
Q

Phototrophic

A

Energy from light

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7
Q

Lithotrophic

A

Reducing equivalents come from inorganic compounds

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8
Q

Organotrophic

A

Reducing equivalents come from organic compounds

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9
Q

Anaerobic terminal electrons acceptors are not found where

A

In food bacteria

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10
Q

Thermophilic

A

Grow at 50C or above

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11
Q

Thermoduric

A

Survive pasteurization

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12
Q

Psychrotrophic

A

Grow in fridge

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13
Q

Cryophilic

A

Grow in freezer

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14
Q

Halophilic

A

Grow in salt

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15
Q

Aciduric

A

Survive at low pH

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16
Q

Turgor pressure

A

Exists because bacteria live in environments more dilute than cytoplasm, causes a net influx of water

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17
Q

Gram positive

A

Thick peptidoglycan

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18
Q

Gram negative

A

Thin peptidoglycan, outer membrane

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19
Q

Teichoic acids

A

On gram positive

30-60% of cell weight, anchored to peptidoglycan

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20
Q

Lipopolysaccharide

A

On gram negative

Lipid A core, repeating oligosaccharide (O antigen)

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21
Q

Sex pili

A

Used for bacteria to attach to each other and transmit DNA from cell to cell
Found in enteric bacteria but not universal among bacteria

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22
Q

K antigen

A

Capsule

Repeats HMW structures to form capsule

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23
Q

O antigen

A

Lipopolysaccharide
Consist of lipid and polysaccharide; joined by covalent bond
In gram negative

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24
Q

F antigen

A

Fimbriae
Both gram neg and pos
Rarely used in classification

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25
H antigen
Flagella | Based on reaction with the flagellin protein
26
5 physiological/physical states of bacteria
Vegetative, injured, VBNC, biofilms, sporulated
27
Injured cell
Can grow on non-selective media but not selective media
28
What can adding a peroxide detox to injured cells do
Help them over come damage caused by oxygen toxicity
29
VBNC
Cannot be cultured on any media even though viability can be demonstrated by non-culturable methods
30
How can VBNC viability be demonstrated
Cytological methods | Substrate responsive metabolism
31
VBNC is most often induced by...
A nutrient limitation
32
Signal transduction
Protein spans membrane, molecule binds protein and elicits response
33
Quorum sensing
Autoinducers diffuse through membrane to elicit response
34
What does auto induced mean
Signal compound is made by a gene product of the same regulon of the thing that is affected (transcribed)
35
Two component signal transduction consists of...
Histidine kinase and response regulator
36
Pleiotrophic
Occurs when one gene influence two or more seemingly unrelated phenotypic traits
37
Endospores
Differentiated cells that are very resistant to heat and cannot be easily destroyed
38
What does it mean that bacterial chromosomes are plastic
The combinations of genes present will be different in every isolate (some missing, some unique)
39
Core genome
Genes shared by all members of a certain group
40
Pangenome
Genes are present in any member of a certain group
41
Accessory genome
Genes that are present in a subset of members of a certain group
42
Prophage
Bacteriophage genome inserted into the circular bacterial DNA chromosome
43
Lysogenic conversion
The process by which a prophage converts a nonpathogenic bacteria to a pathogen
44
Defective prophage
Can no longer form infective phage because of loss of essential genes
45
Why can DNA elements be suspected of being defective prophages
1. not common in all strains of a species | 2. carry genes related to other pathogens
46
Plasmids
Circular molecules of dsDNA that are self replicating (in some cases linear)
47
What do plasmids carry
Genes which encode for products which can benefit the bacteria under certain circumstances
48
Insertion sequence elements
Smallest transposons, only encode the transposon, can interrupt gene function Usually have inverted repeat on either end
49
Composite transposons
When two IS elements bracket other genes and and take them with them when they move
50
Vertical gene transfer
Transmission of DNA from mother to daughter cells
51
HGT
Movement of DNA from one bacteria to another
52
Three divisions of foodborne illness
Intoxication, infection and toxicoinfection
53
Intoxication
Ingestion of toxin that grew in the food | Must be present in its active form
54
Infection
Illness after eating viable cells | Multiply in digestive tract
55
Toxicoinfections
Illness after eating a large number of cells that sporulate, colonize, or die and release the toxin
56
Natural sources of contamination
Surface of cut fruit, damaged tissues, skin, GI tract
57
External sources of contamination
Air, soil, sewage, water, etc.
58
4 factors that influence microbial growth
Temperature, redox potential, pH, water activity
59
For every 10C rise in temp...
Catalytic rate of an enzyme doubles
60
Redox potential
Measures potential energy difference in a system generated by a coupled reaction Something is oxidized, something is reduced
61
Redox potential in food is influenced by...
Chemical composition, processing treatments, and storage condition
62
Fresh food and plants are in a __ state because....
Reduced | BC of the reducing potential of biomolecules (when cell resp stops it changes the redox potential)
63
Why do anaerobes die in the presence of oxygen
They lack superoxide dismutase necessary to scavenge toxic oxygen free radicals
64
Controlled atmosphere packaging
Atmosphere in storage facility is altered | Hard to do
65
Modified atmosphere packaging
Food is enclosed in a high gas barrier packaging material; air is removed from package and flushed with gas(es)
66
Vacuum packaging
Removal of air and then sealed
67
Gas flushing
Used to extend the life of other products such as fresh pasta, bakery products, cooked eggs and fresh seafood
68
Most bacteria have a pH range of...
2-3 units
69
In general, gram pos grow at __ pH than gram neg
lower
70
Acids that have a __ dissociation rate are more problematic for bacteria
Lower
71
What has a low dissociation rate
Weak acids
72
Common acids used in foods
Acetic acid, propionic acid, lactic acid, citric acid, sorbic acid, benzoic acid
73
Citric acid
Antimicrobial activity is unclear
74
Aw: 0 Aw: 1
``` 0 = dry 1 = pure water ```
75
Osmophiles
Organisms live in high sugar environments
76
Xerophiles
Organisms live in very dry environments
77
3 methods for removing water from food
Dehydration Crystallization Adding solutes (salt, sugar, honey, starch)
78
Hurdle technology
Assaults multiple homeostatic processes, most effect when it combines two stressors that act by different mechanisms

Food-Borne Pathogens (14 decks)

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