Part 8: Applied Microbiology Flashcards Preview

MBIO1010 > Part 8: Applied Microbiology > Flashcards

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

Oldest evidence of cheese making

5500 BCE in Poland

2

Oldest winery

4100 BCE in Armenia

3

How long have we been using microbes for food preservation?

Since neolithic

4

Edible fungi

Mushrooms: fungal fruiting bodies

5

Agaricus bisporus

Edible fungi - button and protobellos

6

Edible algae

Seaweed

7

Red algae

Porphyra: Nori (sushi wrap)

8

Brown algae

Macrocystis (Alginate, a thickener)

9

Edible bacteria

Nucleic acid often too concentrated for food

10

Exception for edible bacteria

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

11

Fermented foods

Food products modified biochemically by microbial growth

12

Purposes of food fermentation

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

Indigenous flora

Found naturally in the food

14

Starter culture

From a previous fermentation

15

Homolactic acid fermentation

Yogurt, cheese

16

Propionic acid fermentation

Swiss cheese

17

Heterolactic acid fermentation

Kefir

18

Ethanolic fermentation

Wine, beer

19

Alkaline fermentation

Brie cheese

20

Milk fermentation begins by

Lactic acid fermentation with Lactobacillus and Streptococcus

21

Second step of milk fermentation

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

22

Cleaved peptides coagulate to form

Semisolid curd

23

Whey

Liquid portion of cheese production

24

Steps of cheese production

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

Acidic fermentation food

Cabbage, cucumbers, olives, fermented meats

26

Pickling

Fermentation in brine (high salt)

27

High salt of brine selects for

Gram positive

28

Is a starter culture used in pickling?

It can be used or not

29

What selects against some pathogens in acidic fermentation?

Temperature

30

What organisms are used in acidic fermentation?

Pediococcus, Streptococcus, Lactobacillus, Leuconostoc

31

Initially what was used to rise bread

Natural mixture of wild yeasts and heterolactic acid bacteria

32

Most recent development of what is used to rise bread

Saccharomyces cerevisieae: Baker's yeast

33

What fermentation does bread use?

Ethanolic

34

What causes bread to rise?

CO2

35

How is ethanol removed in bread?

By baking

36

What fermentation does beer use?

Ethanolic fermentation

37

What organism does beer use for fermentation?

Saccharomyces cerevisiae: Brewer's yeast

38

Beer is derived from

Alcoholic fermentation of grain

39

Process of beer

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

40

Primary sugar fermented in beer

Maltose

41

Secondary product in beer

Long-chain alcohols and esters

42

What generates some of the special flavors of beer?

Alcohols and esters

43

What organism does wine use for fermentation?

Saccharomyces cerevisiae: Brewer's yeast

44

What kind of fermentation does wine use?

Ethanolic

45

What does wine derive its alcohol fermentation from?

Fruit, usually grapes

46

Process of wine fermentation

Grapes are crushed to release juices
Yeast ferment sucrose, fructose, and glucose to ethanol

47

What is the difference between white and red wine?

Skin is removed

48

Malolactic fermentation is done through

Oenococcus oeni bacteria

49

Malolactic fermentation

Converts malate to lactate plus CO2 reducing the acidity

50

Fermentation of chocolate is done on

Piles of banana leaves

51

When is fermentation done in chocolate?

Prior to roasting of beans for flavor development

52

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

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

53

How does making chocolate start?

Complex series of natural fermentation

54

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

Because the fermentation involves a succession of populations

55

Food spoilage

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

56

Acid taste

Sour

57

Rancidity

Oxidation of fats

58

Putrefaction

Decomposion of proteins

59

Alkalinity taste

Bitter

60

Food contamination or food poisoning refers to

Presence of pathogens

61

Dairy products are soured by

Excessive fermentation

62

Dairy products are made bitter by

Bacterial proteolysis

63

Meat and poultry are putrefied by

Decarboxyloating bacteria

64

What does decarboxylating bacteria produce?

Amines with noxious odors

65

Seafoods spoil rapidly because

Their unsaturated fatty acids rapidly oxidize (become rancid)

66

How does seafood get its fishy smell?

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

67

Plant foods spoil by

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

68

Listeria monocytogenes

Psychrotrophic bacterium that invades the cells of intestinal epithelium

69

What environment does Listeria monocytogenes grow in?

Under refrigerated conditions

70

Physical means of preservation

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

71

Chemical means of preservation

Organic acids
Esters
Other organic compounds
Inorganic compounds

72

Organic acids used for preservation

Benzoic acid, sorbic acid, and propionic acid

73

Esters used for preservation

Fatty acid esters and benzoic acid esters

74

Other organic compounds used for preservation

Cinnamon and mustard

75

Inorganic compound used for preservation

Salts such as phosphate, nitrates, and sulfites

76

Cinnamon as a preservative

Contains benzene derivative eugenol (a potent antimicrobial agent)

77

Mustard as a preservative

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

78

Industrial microbiology

Commercial exploitation of microbes

79

Industrial microbiology is the production of

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

80

How many people have diabetes?

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

81

Type 1 diabetes

5-10% of cases
Beta-islet cells are destroyed by immune system

82

Type 2 diabetes

90-95% of cases
Insulin receptors on cells desensitized to insulin

83

Insulin

Protein hormone produced by beta-islet cells (pancreas)

84

Who discovered the mechanism of diabetes?

Frederick Banting

85

When was insulin first produced and by who?

1921 by F. Banting and Charles Best

86

Where was the first insulin harvested from?

Animal (dog) pancreas

87

When did large-scale commercial production start?

1923 by Eli Lilly

88

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

Ground up bovine and swine pancreas gland

89

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

Many patients formed antibodies against the foreign proteins
It caused inflammation and allergic response

90

What was the solution for bovine and porcine insulin?

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

91

Structure of insulin

51 amino acids

92

How many chains does insulin have?

2 chains - A and B chain

93

How many amino acids does each chain have?

A chain - 21
B chain - 30

94

What are the chains of insulin held together by?

Disulfide bridges

95

Manufacturing human insulin

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

Pancreatic cancer

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

97

Symptoms of patients with metastasized cancer

Jaundice, pain, weight loss, and fatigue

98

What is the current treatment for pancreatic cancer?

Chemotherapeutic agents that improve median life expectancy for 6 months

99

What is a promising alternative therapy for pancreatic cancer?

Listeria monocytogenes

100

Mechanism of Listeria monocytogenes as treatment

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