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Introductory Microbiology > Food microbiology 2 + industrial microbiology > Flashcards

Food microbiology 2 + industrial microbiology Flashcards

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1
Q

What is food poisoning/intoxication

A

Caused by microbial toxins in food. Symptoms appear quickly

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2
Q

What is food infection

A

Organisms are ingested with the food and multiply in the host. Symptoms take longer to develop. Illness may be due to tissue invasion, production of toxins or both

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3
Q

Top 10 causes of food-borne diseases

A
  1. Leaving cooked foods at room temperature
  2. Lapse of 12 h or more between preparation and consumption
  3. Colonized/ infected persons handling food
  4. Inadequate reheating
  5. Improper hot holding
  6. Contaminated raw food/ingredients
  7. Foods from unsafe sources
  8. Improper cleaning of equipment
  9. Cross contamination -raw to cooked
  10. Inadequate cooking
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4
Q

What diseases do e.coli cause, how many people and by what foods

A

Food infection

63000 per year

Meat, especially ground meat, raw vegetables

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5
Q

What diseases do salmonella cause, how many people and by what foods

A

Food infection

1,340,000 per year

Poultry,meat,dairy, eggs

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6
Q

What diseases do clostridium cause, how many people and by what foods

A

food poisoning and food infection

248,000

Meat and vegetable held improper storage temperature

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7
Q

How botulism happen

A

A food poisoning, ingestion of the neurotoxin produced by Clostridium botulinum

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8
Q

What does botulism cause and the mortality rate

A

10% mortality

Causes flaccid paralysis, respiratory or cardiac failure

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9
Q

Symptoms of botulism

A

Difficulty swallowing, double vision, breathing difficulty, paralysis

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10
Q

Botuslism will take place

A

1-2 days

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11
Q

Clostridium botulinum is anaerobe/aerobe

A

Anaerobe

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12
Q

What is the precaution for Clostridium botulinum and canning

A

Home canning -> insufficient temperature to kill the spores

Processed foods that are not reheated (non-acid canned vegetables , slices meats)

Spores germinate, growth, toxin produced

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13
Q

Temperature and botulism toxin

A

Toxin is destroyed by heating (80C, 10 min). Properly cooked foods are safe to eat; it destroys the toxin, not the organisms

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14
Q

What organisms accounts for 40% of food poisoning cases

A

Staphylococcal

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15
Q

What toxin is secreted by Staphyloccocus aureus

A

Enterotoxin

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16
Q

Enterotoxin stability

A

Relatively heat-stable -> 30 min at 100C , 16H at 60 C and still going to be alive

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17
Q

How can you get S.aureus

A

20-30% of humans are colonized by S.aureus (skin and upper respiratory tract). It is easily transferred to food where it can grow and produce the toxin. Symptoms appear quickly (1-6h):nausea,vomiting, diarrhea

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18
Q

S.aureus are associated with what kind of food

A

Prepared in large quantities and then, left at room temperature (banquet,picnic,airline, meals). Halotolerant-> can grow on salted sausages,etc.

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19
Q

What can be done to prevent S.aureus poisoning

A

Keep cold food and hot food hot.

Adequate sanitation/hygiene

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20
Q

Did we know all strains of salmonella enterica?

A

No, only a fraction.

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21
Q

S.enterica can infect

A

Mammals, birds and reptiles

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22
Q

How salmonella enterica progresses

A

Contaminated food drink-> bacteria travel to small intestine, adhere to lining; begin life cycle

In severe cases, bacteria break through intestinal wall to bloodstream; can be deadly if not properly treated

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23
Q

Who can get a severe case of Salmonella enterica

A

Infants, elderly, people with impaired immune systems

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24
Q

What is salmonellosis

A

when salmonella grows in the intestinal tract

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25
Q

What system does Salmonella uses

A

two injectisome systems

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26
Q

Most common strains of salmonella

A

eteritidis

Typhimurium

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27
Q

How Salmonella enterica transmitted

A

Different routs: water, processing of different types of food

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28
Q

How many organisms of Salmonella enterica are needed to cause disease and what should happen before ingestion

A

10^5-10^8

It must multiply in the food before the food is eaten

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29
Q

Symptoms of Salmonella enterica are caused by

A

Invasion and destruction of the intestinal epithelium

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30
Q

S.enterica is associated with

A

Uncooked or slightly cooked foods, or cooked foods that were cross-contaminated

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31
Q

What helps against S.enterica

A

Good sanitation practices against cross-contamination.

Cooking kills S.enterica

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32
Q

Symptoms of S.enterica

A

Nausea, vomiting, fever diarrhea, abdominal cramps

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33
Q

Why it is difficult to find E.coli O157:H7

A

Fecal coliform but does not grow at 44.5C; escape detection by standard fecal coliform methods

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34
Q

What is EHEC

A

E. coli strain that causes a severe intestinal infection in humans

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35
Q

What is the effective dose of EHEC

A

less than 100 microorganisms

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36
Q

How does EHEc infect humans and what does it do

A

Food infection, attaches to the intestinal mucosa and produces an AB-type exotoxin: Shiga like toxin that inhibits protein synthesis

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37
Q

What is the effect if Shiga toxin

A

The toxin damages the underlying tissues-> causes bloody diarhea (hemorrhagic colitis)

The toxin travels through the blood stream and destroys cells in the kidney-> causes hemolytic uremic syndrome, can result in acute renal failure and death

38
Q

How EHEC can be killed

A

By cooking

39
Q

What are the aims of food processing and preservation

A
  • Prevent or delay decomposition by microorganisms (spoilage)
  • Destroy pathogens or inhibit their growth
  • Prevent or delay self-decomposition by enzymes present in the food
40
Q

How can food processing be achieved (6)

A
  • Refrigeration and freezing
  • Heating (pasteurization)
  • Canning
  • Reducing water availability
  • Irradiation
  • Chemicals
41
Q

What are the enzymes of refrigeration and freezing?

A

Slow or inhibit growth of microorganisms

42
Q

What happens at -20C? (Aw)

A

At -20C the aw can reach 0.82. Most organisms cannot grow

43
Q

What happens once the temperature is persmissive? ( again warm)

A

Viable microorganisms will resume growth

44
Q

What cycle affect the quality of the food (ice crystals)

A

Freeze/thaw

45
Q

What is cereulide

A

Toxin produced by B.cereus (spore-forming)

46
Q

The action of cereulide

A

Attacks the mitochondrion, compromises membrane potential and oxidative phosphorylation

47
Q

The result of the action of cereulide

A

Eventually leads to cell death (apoptosis)

Acute emetic agent (causes vomiting)

especially toxic for liver and pancreas (beta cells)

48
Q

The aim of pasteurization

A

Reduce the number of microorganisms to delay spoilage and to eliminate pathogens

49
Q

Pasteurization is done for what products

A

Dairy, liquid egg products, alcoholic beverages, fruit juice

50
Q

Three methods of pasteurization for milk

A

Long temperature long time (LTLT)

High temperature short time (HTST)

Ultrahigh temperature (UHT)

51
Q

Describe the conditions for LTLT

A

30 min, 62.8C, bad taste(ice cream and cheese)

52
Q

Describe the conditions for HTST

A

HTST: 15 sec, 71.7C (milk for drinking)

53
Q

Describe the conditions for UHT

A

2 sec, 141C (long shelf life at room temperature, virtually sterile)

54
Q

Time AND TEMPERATURE required for pasteurization are affected by

A

The amount of fat, sugar and protein

55
Q

Can raw milk be used for something in Quebec?

A

For cheese making

56
Q

Aim of canning

A

Seal the food from the outside world and heat the container to kill most, if not all, of the microorganisms. It creates an aerobic environment

57
Q

Temperature for canning

A

100 C for acidic food

Up to 121C for low-acid food

58
Q

What is 12D process

A

Temperature and time of exposure must be sufficient to kill 10^12 spores of Clostridium botulinum

59
Q

In canning, there is should be a balance between

A

Food safety, nutritional value and taste of the food

60
Q

Drying: aim

A

Prevent microorganisms from growing by inhibiting water availability

61
Q

Types of drying

A
  • Sun dried
  • Hot air dried
  • Freeze-drying (lyophilization)
62
Q

How can be reducing of water achieved in drying

A

Adding salt or sugar: increases the osmotic strength of the surrounding solution

63
Q

Does drying kill microorganisms?

A

Not necessarily. Just inhibits their growth

64
Q

What is the aim of irradiation?

A

Reduce contamination of fresh product by pathogen and spoilage organisms

65
Q

Dosage of irradiation can be adjusted to

A
  • Kill all microorganisms (radappertization)
  • Kill specific microorganisms (radicidation)
  • Reduce overall contamination (radurization)
66
Q

What are some concerns about irradiating the food?

A

Possible radioactive contamination, production of toxic or carcinogenic compounds, altered nutritional value, production of off-flavor

67
Q

Aim of chemicals and other treatments

A

Control growth of microorganisms (usually selected microorganisms )

68
Q

What are chemicals generally recognized as safe (GRAS) and where they are used

A

Nitrite: prevents outgrowth of C.botulinum

Sulfites: wine industry, inhibits growth wild yeasts

Nisin: bacteriocin produced by lactococcus lactis. Present in cheeses made with lactococcus lactis. Effective against many gram-positive organisms , including lactic acid bacteria

69
Q

What is bacteriohage for food

A

FDA has approved a cocktail of bacteriophages against listeria monocytogenes

70
Q

What is produced during exponential phase

A

Primary metabolites: alcohol

71
Q

What is produced at the end of growth, near or at the stationary phase

A

Antibiotics

72
Q

Major products of Industrial microbiology

A
  • Antibiotics
  • Enzymes
  • Food additives
  • Chemicals
  • Alcoholic beverages
73
Q

What vessel is used for industrial growth of microorganisms

A

Chemostat

74
Q

In industrial microbiology, fermentation refer to

A

Any large-scale microbial process (aerobic or anaerobic)

75
Q

What is controlled in chemostats

A
  • Temperature
  • Nutrients
  • pH
  • Dissolved oxygen
76
Q

What stains are not suitable for industrial use

A

wild-type industry

77
Q

What two types of stains are used in industry

A

Mutant strains that overproduce the desired metabolites; deregulated mutant with respect to desired metabolic pathway. Leads to large scale production of the compound

-Genetically modified organisms. Genes are cloned into and expressed in bacteria or yeasts. Can control expression to synthesize as much ( or as little) product as required

78
Q

What mutant strain is used in industry and is very useful and for what

A

Very useful to produce AAs (Corynebacterium sp.)

79
Q

What is produced with genetically modified strains

A

Human insulin and a variety of enzymes (e.g. rennet)

80
Q

What is somatotrophin

A

_human growth factor

-Deficiency causes heredity dwarfism

81
Q

What can be corrected with human somatotrophin drugs

A

Can correct stunted growth in children

82
Q

How do we get somatotrophin drug

A

Recombinant human somatotrophin gene cloned and expressed in bacteria

83
Q

Bovine somatotrophin: how it is related to cows

A

An average dairy cow begins her lactation with a moderate daily leve of milk production. This daily output increases until, at about 70 days into the lactation, production peaks. From that time until the cow is dry, production slowly decreases. This increase and decrease in production is partially caused by the count of milk-producing cells in the udder. Cell counts begin at a moderate number,increase during the first part of the lactation, then decrease as the lactation proceeds. Once lost, these cells generally do not regrow until the next lactation.

Administration of rBST or BST prior to peak production, in cows that are well-fed, slows the rate at which the number of mammary cells decreases, and increases the amount of nutrients directed away from fat and toward the mammary cells, leading to an extension of peak milk production. The effects are mediated by the insulin-like growth factor (IGF) system, which is upregulated in response to BST or rBST administration in well-fed cows

84
Q

Insulin produced by what type of cells and where

A

In pancreas by beta-cells

85
Q

Why it is necessary to do insulin injections

A

To preserve glucose homeostasis and for survival-> to lower blood sugar levels

86
Q

Insulin was the first ___

A

Human protein to be produced by bacteria

87
Q

What can be done to a plant with bacteria

A

Plants can be genetically engineer herbicide or insect resistance into a crop plant

88
Q

example of herbecide

A

Glyphosate (roundup) kills plants by inhibiting amino acid synsthesize

89
Q

How can be resistance to Glyphosate

A
  • Take gene from Glyphosate resistant bacteria
  • Modify for expression in plants
  • Clone (transfer) into crop plant,
  • End result: crop plant is resistant can use glyphosate to kill weeds
90
Q

How can you develop resistance to insects in plants

A
  • Introduce genes encoding bacterial toxin that is toxic to insect into the plant
  • Plants produce the toxin
  • Insects that come into contact with plant ingest toxin and die
91
Q

Example of plant toxin to insects

A

Bt toxin is very toxic to moths and butterflies (but not mammals)

Introductory Microbiology (21 decks)

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