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BI374 Final > Food microbiology > Flashcards

Food microbiology Flashcards

1
Q

To allow for storage or preservation of food, _____ ______ must be inhibited.

A
  • microbial growth
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2
Q

What are the 5 major conditions that govern microbial growth?

A
  • water availability (Aw)
  • temp
  • O2
  • nutrient availability
  • pH
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2
Q

What are the 5 major conditions that govern microbial growth?

A
  • water activity (Aw)
  • temp
  • O2
  • nutrient availability
  • pH
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3
Q

Define preservation

A
  • protect health quality until consumed
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4
Q

What is food spoilage?

A
  • any change in visual appearance, taste or smell of food product that makes it unacceptable to consumer (unsafe)
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5
Q

What does perishable mean? What does this depend on?

A
  • degradation sensitivity
  • water content (encourages growth)
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6
Q

Give examples of highly perishable foods

A
  • meats, fish, poultry, eggs, milk, most fruits and veggies
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7
Q

Give examples of semi-perishable foods

A
  • potatoes, some apples, nuts
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8
Q

Give examples of stable/nonperishable foods

A
  • sugar, flour, rice, dry beans
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9
Q

perishable status is related to _____ _____ –> stable foods have ____ _____ ______.

A
  • moisture content
  • lower water activity
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10
Q

What kind of bacteria attack meat? Give an example.

A
  • enteric
  • E. coli/salmonella
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11
Q

What kind of bacteria attack dairy products? Give an example.

A
  • lactic acid
  • lactobacillus (probiotic/prebiotic)
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12
Q

Deterioration occurs _____ it shows

A
  • before
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13
Q

What is the result of food spoilage?

A
  • microbial growth and enzyme production where metabolites and waste products contribute to spoilage
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14
Q

What is the origin of salmonella, shigella, E.coli and campylobacter?

A
  • meats (GI adapted)
  • outside and gets blended in
  • hide in fat deposits
  • protected from freezing
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15
Q

What is the origin of pseudomonas and aspergillus?

A
  • soil (fruits/veggies)
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16
Q

The lower the temp, the __ ____ the spoilage rate.

A
  • less rapid
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17
Q

psychrotolerant microorganisms are less ____ by fridge temp

A
  • inhibited
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18
Q

What pH do bacteria typically like? what part of the human body has this pH?

A
  • neutral
  • colon
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19
Q

What is a suicide bacteria?

A
  • generate products during growth that drop pH and kill them
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20
Q

What is pickling?

A
  • addition of acid (vinegar) to prevent microbial growth
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21
Q

How does acidity develop naturally?

A
  • microbial action (lactics, acetic acid bacteria)
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22
Q

How can microbial growth be controlled? what are some examples?

A
  • lowering water activity
  • addition of salt, sugar, drying
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23
Q

What is canning?

A
  • heat sterilization process where food is sealed + heated to kill all living organism and ensure no residual growth in can
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24
What does heat sterilization, sealing and more heat prevent?
- microbial growth and gas production
25
What causes microbes to be more tolerant to canning?
- form spores (multiple layers) - resist drying conditions and survive with no O2
26
What does botulism cause? What bacteria causes this?
- muscle paralysis unless bacteria dies off - clostridium botulinum (heat sensitive and found in soil)
27
What is pasturization?
- low heat for a long time
28
What allows gram positive bacteria to be more tolerant?
- thicker peptidoglycan in cell wall
29
State + describe 3 abiotic parameters that can be manipulated to control growth in food products
- temp - lower slows growth/higher kills (fridge/canning) - pH - neutral is favoured, increase acidity/base (add vinegar) - moisture (Aw) - dry gives less nutrients (freeze dry/salt)
30
What chemicals can be added to food that are classified as being "safe"?
- sodium propionate, nitrites, ethylene oxide, antibiotics
31
What is biotechology?
- use of living organisms to carry out defined chemical processes for industrial application
32
What is genetic engineering?
- develop sophisticated procedures for isolation, manipulation and expression of genetic material
33
Give an example of how genetic engineering has been useful for commercial application
- insulin production
34
What is molecular cloning?
- isolation and purification of fragment of DNA into a vector where it can be replicated
35
What is a vector?
- vehicle for transmission
36
What application does molecular cloning have?
- industrial (produces large amounts)
37
What does molecular cloning aim to do?
- isolate large quantities of specific genes in their pure form
38
What is the strategy of molecular cloning?
- move desired gene from large complex genome to small simple one (faster replication)
39
What is a natural vector?
plasmids
40
Why are plasmids used as cloning vectors?
- carry other genes along with required ones for growth and replication
41
How do plasmids replicate?
- independently of host genome
42
What is a plasmid
- genetic material independently generated - taken up by other organisms, (HGT)
43
What are the 5 advantages of plasmids as cloning vectors?
- small (DNA easier to isolate/manipulate) - stability of circular DNA - independent origin of replication - multiple copy number - contain selectable markers
44
What does multiple copy number mean?
- can be present in cell in numerous copies so DNA amplification is possible
45
What does it mean when a plasmid has selectable markers?
- ex. microbial resistant genes - makes detection and selection of plasmid-containing clones easier
46
What must happen to achieve biological containment?
- plasmid vectors are modified to prevent conjugative transfer
47
What is conjugative treansfer?
- artificial creation
48
What is electroporation?
- fire holes into plasmid to allow takeup (LAB PROCESS)
49
What are other cloning vectors?
- bacteriophage lambda, yeast artificial chromosomes
50
What are ideal characteristics for hosts of cloned genes?
- rapid growth - capability of growth in inexpensive culture medium - not harmful/pathogenic - ability to take up DNA (competent) - stability in culture
51
What allows for replication of the vector?
- appropriate enzymes
52
What are the 6 molecular techniques?
- restriction of endonucleases to cut DNA; use ligase to fix - vectors carry DNA - hosts can clone large #s of identical gene sequences - polymerase chain reaction = novel procedure to amplify DNA - synthetic DNA sequences created in lab - site-directed mutagenesis - create mutations at specific locations in genome
53
What are the 8 practical applications of genetic engineering?
- microbial fermentation - virus vaccines - mammalian proteins - transgenic plants and animals - environmental biotechnology - gene regulation and therapy - bioleaching - oil recovery
54
What is the practical application of microbial fermentation?
genetic engineering procedures can be used to manipulate organism to obtain increased yields of desirable product - ex. antibiotics
55
What is the practical application of virus vaccines?
- production of viral protein coat separately from rest of virus particle (protein coat is active ingredient)
56
What happens when the protein coat is pulled off the virus?
- stimulates it then is attenuated so the entire organism is inactivated - host needs to identify it
57
What is the practical application of mammalian proteins?
- commercial production possible by cloning gene for human protein in appropriate microorganism
58
Insulin in its active form consists of ____ _______ (A and B) connected by _____ _____
- 2 polypeptides - disulfide bridges
59
why is insulin a suitable host?
- large, 2 chains and chunks that are joined
60
What is the practical application of transgenic plants and animals?
- alter whole plants/animals can boost agricultural productivity or later nutritional quality of meats and veggies (more natural feeding than antibiotics) - some cases: foreign DNA inserted directly into cells by bacterium
61
What doe agrobacterium tumefaciens do? How was it utilized for good?
- inserts infection tube to plant for disease (natural infection) - inactivated disease portion and replaced it with beneficial
62
What is the practical application of environmental biotechnology?
- large existing gene pool in bacteria, genes may code for proteins that degrade environmental pollutants and toxic waste - can use selective enrichment techniques to isolate strains with degradation capacity - can use genetically engineered "ice-minus" to reduce damage to crops (freezing)
63
What does ice nucleating pseudomonas syringae do?
- on surface of crop leaves, supercools water at 0 - ice + crystallizes leaf above and speeds frosting - it tolerates conditions with insulating biofilm (protected) and hurts other organisms
64
How was ice nucleation taken advantage of?
- naturally occuring reverse mutation is ice - - lacks nucleating gene but has everything else - protects plant from freezing and damage and can tolerate below freezing while still being protected -PROTECT PLANT FROM ICE + AND NATURAL LOSS
65
How is ice nucleating gene exploited?
- used on skii hill
66
What is the practical application of gene regulation/therapy?
- designer drugs and regulation of expression of certain genes - gene therapy used for genetic disease treatment
67
What is the practical application of bioleaching?
- use of microbial activity to gain access to a product - use bacteria that can perform specific function
68
How is bioleaching used for the recovery of metals?
- used for low grade copper and uranium ores - leaching involves extraction of metal with organic solvent - metal removed from solvent
69
What is the practical application of oil recovery
- use microorganisms that produce xanthan gums - some produce materials that free oil from sediments in production wells to pull it up

BI374 Final (12 decks)

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