Part 8: Applied Microbiology Flashcards Preview

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Flashcards in Part 8: Applied Microbiology Deck (100)
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1
Q

Oldest evidence of cheese making

A

5500 BCE in Poland

2
Q

Oldest winery

A

4100 BCE in Armenia

3
Q

How long have we been using microbes for food preservation?

A

Since neolithic

4
Q

Edible fungi

A

Mushrooms: fungal fruiting bodies

5
Q

Agaricus bisporus

A

Edible fungi - button and protobellos

6
Q

Edible algae

A

Seaweed

7
Q

Red algae

A

Porphyra: Nori (sushi wrap)

8
Q

Brown algae

A

Macrocystis (Alginate, a thickener)

9
Q

Edible bacteria

A

Nucleic acid often too concentrated for food

10
Q

Exception for edible bacteria

A

Cyanobacteria, Spirulina is used as a single-celled protein source and nutritional supplement

11
Q

Fermented foods

A

Food products modified biochemically by microbial growth

12
Q

Purposes of food fermentation

A

To preserve food: by limiting growth of spoilage organisms and also many pathogens
To improve digestibility: for example by breaking down lactose
To add nutrients (such as vitamins) and flavor (such as esters and sulfur compounds)

13
Q

Indigenous flora

A

Found naturally in the food

14
Q

Starter culture

A

From a previous fermentation

15
Q

Homolactic acid fermentation

A

Yogurt, cheese

16
Q

Propionic acid fermentation

A

Swiss cheese

17
Q

Heterolactic acid fermentation

A

Kefir

18
Q

Ethanolic fermentation

A

Wine, beer

19
Q

Alkaline fermentation

A

Brie cheese

20
Q

Milk fermentation begins by

A

Lactic acid fermentation with Lactobacillus and Streptococcus

21
Q

Second step of milk fermentation

A

Rennet protelysis (by chymosin and pepsin), rendering casein insoluble

22
Q

Cleaved peptides coagulate to form

A

Semisolid curd

23
Q

Whey

A

Liquid portion of cheese production

24
Q

Steps of cheese production

A

Milk is filtered and subjected to pasteurization
Fermenting microbes are added as a starter culture of different mixtures of bacteria for different cheeses
Drop in pH and/or added rennet (stomach proteases) help denature the milk protein called casein, which coagulates and precipitates out of solutions (curds)
Solid curd is cut
Curd is lightly heat-treated
Pressed curd is shaped into a mold
Cheese is ripened

25
Q

Acidic fermentation food

A

Cabbage, cucumbers, olives, fermented meats

26
Q

Pickling

A

Fermentation in brine (high salt)

27
Q

High salt of brine selects for

A

Gram positive

28
Q

Is a starter culture used in pickling?

A

It can be used or not

29
Q

What selects against some pathogens in acidic fermentation?

A

Temperature

30
Q

What organisms are used in acidic fermentation?

A

Pediococcus, Streptococcus, Lactobacillus, Leuconostoc

31
Q

Initially what was used to rise bread

A

Natural mixture of wild yeasts and heterolactic acid bacteria

32
Q

Most recent development of what is used to rise bread

A

Saccharomyces cerevisieae: Baker’s yeast

33
Q

What fermentation does bread use?

A

Ethanolic

34
Q

What causes bread to rise?

A

CO2

35
Q

How is ethanol removed in bread?

A

By baking

36
Q

What fermentation does beer use?

A

Ethanolic fermentation

37
Q

What organism does beer use for fermentation?

A

Saccharomyces cerevisiae: Brewer’s yeast

38
Q

Beer is derived from

A

Alcoholic fermentation of grain

39
Q

Process of beer

A

Barley grains are germinated, allowing enzymes to break down the starch to maltose for yeast fermentation

40
Q

Primary sugar fermented in beer

A

Maltose

41
Q

Secondary product in beer

A

Long-chain alcohols and esters

42
Q

What generates some of the special flavors of beer?

A

Alcohols and esters

43
Q

What organism does wine use for fermentation?

A

Saccharomyces cerevisiae: Brewer’s yeast

44
Q

What kind of fermentation does wine use?

A

Ethanolic

45
Q

What does wine derive its alcohol fermentation from?

A

Fruit, usually grapes

46
Q

Process of wine fermentation

A

Grapes are crushed to release juices

Yeast ferment sucrose, fructose, and glucose to ethanol

47
Q

What is the difference between white and red wine?

A

Skin is removed

48
Q

Malolactic fermentation is done through

A

Oenococcus oeni bacteria

49
Q

Malolactic fermentation

A

Converts malate to lactate plus CO2 reducing the acidity

50
Q

Fermentation of chocolate is done on

A

Piles of banana leaves

51
Q

When is fermentation done in chocolate?

A

Prior to roasting of beans for flavor development

52
Q

How are scientists trying to standardize the process of chocolate making?

A

They are trying to develop a defined starter culture in order to perform the fermentation in a controlled way

53
Q

How does making chocolate start?

A

Complex series of natural fermentation

54
Q

Why is it difficult to find a starter culture for chocolate?

A

Because the fermentation involves a succession of populations

55
Q

Food spoilage

A

Refers to microbial changes that render a product obviously unfit or unpalatable for consumption

56
Q

Acid taste

A

Sour

57
Q

Rancidity

A

Oxidation of fats

58
Q

Putrefaction

A

Decomposion of proteins

59
Q

Alkalinity taste

A

Bitter

60
Q

Food contamination or food poisoning refers to

A

Presence of pathogens

61
Q

Dairy products are soured by

A

Excessive fermentation

62
Q

Dairy products are made bitter by

A

Bacterial proteolysis

63
Q

Meat and poultry are putrefied by

A

Decarboxyloating bacteria

64
Q

What does decarboxylating bacteria produce?

A

Amines with noxious odors

65
Q

Seafoods spoil rapidly because

A

Their unsaturated fatty acids rapidly oxidize (become rancid)

66
Q

How does seafood get its fishy smell?

A

Psychotrophic bacteria reduce TMAO (trimethylamineoxide) to the fishy-smelling trimethylamine

67
Q

Plant foods spoil by

A

Excess growth of bacteria and molds which can cause them to wilt, brown, and lose texture

68
Q

Listeria monocytogenes

A

Psychrotrophic bacterium that invades the cells of intestinal epithelium

69
Q

What environment does Listeria monocytogenes grow in?

A

Under refrigerated conditions

70
Q

Physical means of preservation

A
Dehydration and lyophilization (freeze-drying)
Controlled or modified atmosphere
Pasteurization
Canning
Ionizing radiation
Refrigeration and freezing
71
Q

Chemical means of preservation

A

Organic acids
Esters
Other organic compounds
Inorganic compounds

72
Q

Organic acids used for preservation

A

Benzoic acid, sorbic acid, and propionic acid

73
Q

Esters used for preservation

A

Fatty acid esters and benzoic acid esters

74
Q

Other organic compounds used for preservation

A

Cinnamon and mustard

75
Q

Inorganic compound used for preservation

A

Salts such as phosphate, nitrates, and sulfites

76
Q

Cinnamon as a preservative

A

Contains benzene derivative eugenol (a potent antimicrobial agent)

77
Q

Mustard as a preservative

A

Contains sinalbin which can release isothiocyanate, which is toxic to bacteria

78
Q

Industrial microbiology

A

Commercial exploitation of microbes

79
Q

Industrial microbiology is the production of

A

Vaccines, pharmaceuticals, and therapeutics
Industrial solvents, biodegradable plastic
Genetically modified plant and animal cells

80
Q

How many people have diabetes?

A

2.4 million Canadians
6.8% of population
1/11 Canadians over 20

81
Q

Type 1 diabetes

A

5-10% of cases

Beta-islet cells are destroyed by immune system

82
Q

Type 2 diabetes

A

90-95% of cases

Insulin receptors on cells desensitized to insulin

83
Q

Insulin

A

Protein hormone produced by beta-islet cells (pancreas)

84
Q

Who discovered the mechanism of diabetes?

A

Frederick Banting

85
Q

When was insulin first produced and by who?

A

1921 by F. Banting and Charles Best

86
Q

Where was the first insulin harvested from?

A

Animal (dog) pancreas

87
Q

When did large-scale commercial production start?

A

1923 by Eli Lilly

88
Q

What was the first large-scale commercial production made of?

A

Ground up bovine and swine pancreas gland

89
Q

What happened when human were injected with bovine and porcine insulin?

A

Many patients formed antibodies against the foreign proteins

It caused inflammation and allergic response

90
Q

What was the solution for bovine and porcine insulin?

A

Insert human insulin gene into E. coli to produce human insulin - recombinant DNA technology

91
Q

Structure of insulin

A

51 amino acids

92
Q

How many chains does insulin have?

A

2 chains - A and B chain

93
Q

How many amino acids does each chain have?

A

A chain - 21

B chain - 30

94
Q

What are the chains of insulin held together by?

A

Disulfide bridges

95
Q

Manufacturing human insulin

A

DNA containing the A-chain genes and B-chain gene individual cloned into a plasmid vector
The recombinant plasmids DNA are then introduced into E. coli
Bacteria containing hte plasmid grown as large-scale cultures in fermenters
Become insulin factories that produce large amount of A-chain and B-chain polypeptide

96
Q

Pancreatic cancer

A

Highly aggressive
Poor survival rate - less than 4% of people survive 5 years after diagnosis
“Silent killer” - cancer spreads before primary tumor detected

97
Q

Symptoms of patients with metastasized cancer

A

Jaundice, pain, weight loss, and fatigue

98
Q

What is the current treatment for pancreatic cancer?

A

Chemotherapeutic agents that improve median life expectancy for 6 months

99
Q

What is a promising alternative therapy for pancreatic cancer?

A

Listeria monocytogenes

100
Q

Mechanism of Listeria monocytogenes as treatment

A

L.m deliver anticancer radionuclides - targets and kills cancer skills
Anti-Listeria antibody linked to 188Re used to tag bacteria with deadly radioactivity