Environmental Effects On Microbial Growth

Question 1

Growth at pH <5.5

Answer 1

Acidophiles

Question 2

How to successfully cultivate anaerobic

Answer 2

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

Question 3

Proteins of thermophiles are

Answer 3

• more heat-stable
• structures

Question 4

Prefer high sugar conc.

Answer 4

Osmophiles

Question 5

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

Answer 5

Glycerol, DMSO (dimethyl sulfoxide)

Question 6

What can destroy superoxide anion and hydroxyl radical

Answer 6

Superoxide dismutase (enzyme)

Question 7

Describe obligate aerobe

Answer 7

Cells grow on or near oxic zone

Question 8

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

Answer 8

Optimum

Question 9

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

Answer 9

True

Question 10

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

Answer 10

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

Question 11

Highest temp. in which cells begin to die

Answer 11

Maximum

Question 12

What proteins do psychrophiles have and what is their function?

Answer 12

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

Question 13

How to increase aeration in lab

Answer 13

Shake vessel manually or use incubator shaker

Question 14

Do not require oxygen

Answer 14

Anaerobic

Question 15

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

Answer 15

growth does not occur

Question 16

Where to find halophilic organisms

Answer 16

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

Question 17

What can counter triplet and singlet oxygen

Answer 17

Carotenoids

Question 18

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

Answer 18

Stiff and waxy

Question 19

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

Answer 19

Minimum

Question 20

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

Answer 20

reduced water availability for the microorganism

Question 21

Cytoplasmic membrane of thermophiles contain

Answer 21

saturated, FA

Question 22

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

Answer 22

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

Question 23

Require normal/elevated levels of oxygen

Answer 23

Aerobic

Question 24

Example of nonhalophile

Answer 24

E. coli

Question 25

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

Answer 25

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

Question 26

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

Answer 26

Msophile

Question 27

Extreme halophiles require

Answer 27

15-30% NaCl

Question 28

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

Answer 28

Polymerase Chain Reaction (PCR)

Question 29

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

Answer 29

- watermelon snow - chlorophyll, carotenoid

Question 30

Growth at pH >8

Answer 30

Alkaliphiles

Question 31

What happens when ice crystals are formed in cells?

Answer 31

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

Question 32

How to increase aeration in lab

Answer 32

Shake vessel manually or use incubator shaker

Question 33

Prefer dry envi

Answer 33

Xerophiles

Question 34

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

Answer 34

Taq polymerase

Question 35

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

Answer 35

Cardinal temperature

Question 36

Halotolerant can

Answer 36

withstand low conc. salt but will grow best without it

Question 37

Describe aerotolerant anaerobes

Answer 37

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

Question 38

Superoxide anion and hydroxyl radical are

Answer 38

Strong oxidizing agents that can affect membrane and protein stability

Question 39

Hydrogen peroxide can

Answer 39

affect and damage various cell components

Question 40

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

Answer 40

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

Question 41

Describe microaerophiles

Answer 41

Require reduced levels of oxygen, prefer area near anoxic

Question 42

Describe obligate anaerobe

Answer 42

Settle towards bottom of tube

Question 43

Example of anaerobic organism

Answer 43

Clostridium tetanii

Question 44

How to destroy hydrogen peroxide

Answer 44

Catalase and peroxidase

Question 45

Describe facultative aerobe

Answer 45

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

Question 46

Most natural environment, growth at pH 5.5-7.9

Answer 46

Neutrophiles

Question 47

Psychrophiles have an abundance of

Answer 47

Unsaturated, short chain fatty acids in its cytoplasmic membrane

Question 48

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

Answer 48

Proteases, lipases

Question 49

Found in unusually hot temperature

Answer 49

Hyperthermophile

Question 50

Cytoplasmic membrane of thermophiles contain

Answer 50

saturated, FA

Question 51

Water activity is applied in food products to

Answer 51

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

Question 52

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

Answer 52

Mesophile

Question 53

True or false. Lipid monolayers are present in Archaea.

Answer 53

True.

Question 54

Cells in maximum die bc?

Answer 54

Protein denaturation, cell lysis

Question 55

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

Answer 55

maintaining fluidity in the cytoplasmic membrane

Question 56

Source of Taq polymerase

Answer 56

Thermus aquaticus (thermophilic organism)

Question 57

Thrive in extremely cold environments

Answer 57

Psychrophile

Question 58

Early food preservation techniques

Answer 58

Drying and curing

Question 59

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

Answer 59

Mesophile

Question 60

Can survive hotter temp.

Answer 60

Hyperthermophile

Question 61

Alkaphiles are salt-loving, they are also called as

Answer 61

Halophilic