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MICROBIO LEC > Environmental Effects On Microbial Growth > Flashcards

Environmental Effects On Microbial Growth Flashcards

1
Q

Growth at pH <5.5

A

Acidophiles

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2
Q

How to successfully cultivate anaerobic

A

Put in anoxic jar (air tight jar that has gas pack which allows chem. reaction that removes oxygen)

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3
Q

Proteins of thermophiles are

A
  • more heat-stable
  • structures
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4
Q

Prefer high sugar conc.

A

Osmophiles

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5
Q

What can be added to mimic cryoprotectant in lab (to a cell suspension to preserve growing culture of bacteria)?

A

Glycerol, DMSO (dimethyl sulfoxide)

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6
Q

What can destroy superoxide anion and hydroxyl radical

A

Superoxide dismutase (enzyme)

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7
Q

Describe obligate aerobe

A

Cells grow on or near oxic zone

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8
Q

Cell grows at a rapid pace and metabollic reactions are continuously occuring

A

Optimum

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9
Q

True or false. Damage to cell at maximum temp. is irreversible.

A

True

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10
Q

True or false. Animal fat (e.g. butter) becomes solid in low temp. compared to plant fat (e.g. olive oil) that remains liquid.

A

True. Animal fat is saturated while plant fat is unsaturated.

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11
Q

Highest temp. in which cells begin to die

A

Maximum

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12
Q

What proteins do psychrophiles have and what is their function?

A

Cold-shock proteins: maintains activity = binds to mRNA (facilitate translation process of central dogma)
Cryoprotectants (anti-freeze): prevents formation of ice

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13
Q

How to increase aeration in lab

A

Shake vessel manually or use incubator shaker

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14
Q

Do not require oxygen

A

Anaerobic

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15
Q

Enzymatic reactions come to a stop in minimum temp. which means

A

growth does not occur

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16
Q

Where to find halophilic organisms

A

Marine environment, 3% NaCl (requirement for salt is absolute)

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17
Q

What can counter triplet and singlet oxygen

A

Carotenoids

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18
Q

If FA is saturated + long chain, what will happen to the cytoplasmic membrane when subjected to low temperatures

A

Stiff and waxy

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19
Q

Lowest temperature in which cells begin to freeze (cytoplasm and cell membrane become less fluid)

A

Minimum

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20
Q

If there are certain solutes present that can bind to water, it can mean

A

reduced water availability for the microorganism

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21
Q

Cytoplasmic membrane of thermophiles contain

A

saturated, FA

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22
Q

True or false. Lipids are unusual in psychrophiles. Why? [TO BE REVIEWED]

A

True. Because polyunsaturated FA are uncommon in prokaryotes. FA is necessary as it maintains the viability of lipids.

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23
Q

Require normal/elevated levels of oxygen

A

Aerobic

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24
Q

Example of nonhalophile

A

E. coli

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25
Q

True or false. The higher the water acitivity, the better.

A

False. The lower, the better. Microorganisms in general are unable to thrive in very low water activity.

26
Q

Pathogenic to us humans bc they colonize our systems where temperature is optimal for their growth

A

Msophile

27
Q

Extreme halophiles require

A

15-30% NaCl

28
Q

A machine that helps amplify a single strand of DNA, like a photocopying machine for DNA samples

A

Polymerase Chain Reaction (PCR)

29
Q

Chlamydomonas nivalis is also called as (blank). What pigments are present in this microorganism?

A
  • watermelon snow
  • chlorophyll, carotenoid
30
Q

Growth at pH >8

A

Alkaliphiles

31
Q

What happens when ice crystals are formed in cells?

A

Cell eventually dies bc when ice thaws, it may puncture cell membrane or wall leading to cell lysis

32
Q

How to increase aeration in lab

A

Shake vessel manually or use incubator shaker

33
Q

Prefer dry envi

A

Xerophiles

34
Q

Enzymes that help in PCR, can withstand high temperatures in machine

A

Taq polymerase

35
Q

Gives us the range of temperatures can grow optimally, and which minimum or maximum temp. the cells begins to die

A

Cardinal temperature

36
Q

Halotolerant can

A

withstand low conc. salt but will grow best without it

37
Q

Describe aerotolerant anaerobes

A

Can tolerate and grow in oxic but cannot use it, evenly distributed in culture medium

38
Q

Superoxide anion and hydroxyl radical are

A

Strong oxidizing agents that can affect membrane and protein stability

39
Q

Hydrogen peroxide can

A

affect and damage various cell components

40
Q

True or false. The higher the water acitivity, the better.

A

False. The lower, the better. Microorganisms in general are unable to thrive in very low water activity.

41
Q

Describe microaerophiles

A

Require reduced levels of oxygen, prefer area near anoxic

42
Q

Describe obligate anaerobe

A

Settle towards bottom of tube

43
Q

Example of anaerobic organism

A

Clostridium tetanii

44
Q

How to destroy hydrogen peroxide

A

Catalase and peroxidase

45
Q

Describe facultative aerobe

A

Under right culture condition, it will grow in both (evenly distibuted)

46
Q

Most natural environment, growth at pH 5.5-7.9

A

Neutrophiles

47
Q

Psychrophiles have an abundance of

A

Unsaturated, short chain fatty acids in its cytoplasmic membrane

48
Q

Certain alkaliphiles produce enzymes that digest proteins known as (blank) and enzymes that digest lipids known as (blank)

A

Proteases, lipases

49
Q

Found in unusually hot temperature

A

Hyperthermophile

50
Q

Cytoplasmic membrane of thermophiles contain

A

saturated, FA

51
Q

Water activity is applied in food products to

A

Determine food contam, how long it can be kept before it starts to spoil, etc.

52
Q

Ubiquitous, you find them everywhere usually but more commonly found in warm-blooded animals and in terrestrial and aquatic environment

A

Mesophile

53
Q

True or false. Lipid monolayers are present in Archaea.

A

True.

54
Q

Cells in maximum die bc?

A

Protein denaturation, cell lysis

55
Q

The presence of unsaturated, short chain FA helps the cell by

A

maintaining fluidity in the cytoplasmic membrane

56
Q

Source of Taq polymerase

A

Thermus aquaticus (thermophilic organism)

57
Q

Thrive in extremely cold environments

A

Psychrophile

58
Q

Early food preservation techniques

A

Drying and curing

59
Q

Pathogenic to us humans bc they colonize our systems where temperature is optimal for their growth

A

Mesophile

60
Q

Can survive hotter temp.

A

Hyperthermophile

61
Q

Alkaphiles are salt-loving, they are also called as

A

Halophilic

MICROBIO LEC (6 decks)

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