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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
Q

What does heat sterilization, sealing and more heat prevent?

A
  • microbial growth and gas production
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25
Q

What causes microbes to be more tolerant to canning?

A
  • form spores (multiple layers)
  • resist drying conditions and survive with no O2
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26
Q

What does botulism cause? What bacteria causes this?

A
  • muscle paralysis unless bacteria dies off
  • clostridium botulinum (heat sensitive and found in soil)
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27
Q

What is pasturization?

A
  • low heat for a long time
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28
Q

What allows gram positive bacteria to be more tolerant?

A
  • thicker peptidoglycan in cell wall
29
Q

State + describe 3 abiotic parameters that can be manipulated to control growth in food products

A
  • 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
Q

What chemicals can be added to food that are classified as being “safe”?

A
  • sodium propionate, nitrites, ethylene oxide, antibiotics
31
Q

What is biotechology?

A
  • use of living organisms to carry out defined chemical processes for industrial application
32
Q

What is genetic engineering?

A
  • develop sophisticated procedures for isolation, manipulation and expression of genetic material
33
Q

Give an example of how genetic engineering has been useful for commercial application

A
  • insulin production
34
Q

What is molecular cloning?

A
  • isolation and purification of fragment of DNA into a vector where it can be replicated
35
Q

What is a vector?

A
  • vehicle for transmission
36
Q

What application does molecular cloning have?

A
  • industrial (produces large amounts)
37
Q

What does molecular cloning aim to do?

A
  • isolate large quantities of specific genes in their pure form
38
Q

What is the strategy of molecular cloning?

A
  • move desired gene from large complex genome to small simple one (faster replication)
39
Q

What is a natural vector?

A

plasmids

40
Q

Why are plasmids used as cloning vectors?

A
  • carry other genes along with required ones for growth and replication
41
Q

How do plasmids replicate?

A
  • independently of host genome
42
Q

What is a plasmid

A
  • genetic material independently generated
  • taken up by other organisms, (HGT)
43
Q

What are the 5 advantages of plasmids as cloning vectors?

A
  • small (DNA easier to isolate/manipulate)
  • stability of circular DNA
  • independent origin of replication
  • multiple copy number
  • contain selectable markers
44
Q

What does multiple copy number mean?

A
  • can be present in cell in numerous copies so DNA amplification is possible
45
Q

What does it mean when a plasmid has selectable markers?

A
  • ex. microbial resistant genes
  • makes detection and selection of plasmid-containing clones easier
46
Q

What must happen to achieve biological containment?

A
  • plasmid vectors are modified to prevent conjugative transfer
47
Q

What is conjugative treansfer?

A
  • artificial creation
48
Q

What is electroporation?

A
  • fire holes into plasmid to allow takeup (LAB PROCESS)
49
Q

What are other cloning vectors?

A
  • bacteriophage lambda, yeast artificial chromosomes
50
Q

What are ideal characteristics for hosts of cloned genes?

A
  • rapid growth
  • capability of growth in inexpensive culture medium
  • not harmful/pathogenic
  • ability to take up DNA (competent)
  • stability in culture
51
Q

What allows for replication of the vector?

A
  • appropriate enzymes
52
Q

What are the 6 molecular techniques?

A
  • 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
Q

What are the 8 practical applications of genetic engineering?

A
  • microbial fermentation
  • virus vaccines
  • mammalian proteins
  • transgenic plants and animals
  • environmental biotechnology
  • gene regulation and therapy
  • bioleaching
  • oil recovery
54
Q

What is the practical application of microbial fermentation?

A

genetic engineering procedures can be used to manipulate organism to obtain increased yields of desirable product
- ex. antibiotics

55
Q

What is the practical application of virus vaccines?

A
  • production of viral protein coat separately from rest of virus particle (protein coat is active ingredient)
56
Q

What happens when the protein coat is pulled off the virus?

A
  • stimulates it then is attenuated so the entire organism is inactivated
  • host needs to identify it
57
Q

What is the practical application of mammalian proteins?

A
  • commercial production possible by cloning gene for human protein in appropriate microorganism
58
Q

Insulin in its active form consists of ____ _______ (A and B) connected by _____ _____

A
  • 2 polypeptides
  • disulfide bridges
59
Q

why is insulin a suitable host?

A
  • large, 2 chains and chunks that are joined
60
Q

What is the practical application of transgenic plants and animals?

A
  • 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
Q

What doe agrobacterium tumefaciens do? How was it utilized for good?

A
  • inserts infection tube to plant for disease (natural infection)
  • inactivated disease portion and replaced it with beneficial
62
Q

What is the practical application of environmental biotechnology?

A
  • 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
Q

What does ice nucleating pseudomonas syringae do?

A
  • 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
Q

How was ice nucleation taken advantage of?

A
  • 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
Q

How is ice nucleating gene exploited?

A
  • used on skii hill
66
Q

What is the practical application of gene regulation/therapy?

A
  • designer drugs and regulation of expression of certain genes
  • gene therapy used for genetic disease treatment
67
Q

What is the practical application of bioleaching?

A
  • use of microbial activity to gain access to a product
  • use bacteria that can perform specific function
68
Q

How is bioleaching used for the recovery of metals?

A
  • used for low grade copper and uranium ores
  • leaching involves extraction of metal with organic solvent
  • metal removed from solvent
69
Q

What is the practical application of oil recovery

A
  • 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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