Microbial Growth

Question 0

What is the temp range for mesophiles?

Answer 0

Between 25C and 45C.

Question 1

What is the temp range for psychrophiles?

Answer 1

-5 C to 15C

Question 2

What is the optimum temp for growth in the human body?

Answer 2

Between 35C and 40C

Question 3

What is the temp range for thermophiles?

Answer 3

Between 45C and 70C.

Question 4

Obligate aerobes have an absolute requirement for what?

Answer 4

Oxygen

Question 5

What do obligate aerobes use oxygen for?

Answer 5

To generate energy via aerobic respiration

Question 6

What cannot happen if oxygen is present with obligate anaerobes?

Answer 6

Cannot multiply, often killed by traces of oxygen because of toxic derivatives.

Question 7

Do facultative anaerobes grow better or worse with oxygen present?

Answer 7

Better. Because aerobic respiration yields the most ATP

*but can also grow without it.

Question 8

How much oxygen do microaerophiles require for aerobic respiration?

Answer 8

Small amounts (2-10%) 
Higher concentrations are inhibitory.

Question 9

Describe aerotolerant anaerobes

Answer 9

Indifferent to oxygen.

Can grow in O2 presence but do not use it to transform energy.

Question 10

What are some toxic derivatives of oxygen?

Answer 10

Superoxide
Hydrogen peroxide
OH*

Question 11

How is hydrogen peroxide toxic?

Answer 11

It is an oxidizing agent

Does not damage the cell as much as superoxide

Question 12

Which toxic derivative of oxygen is very damaging but transient in cells?

Answer 12

OH*

Question 13

What converts O2- to H2O2 and O2?

Answer 13

Superoxide dismutase

Question 14

What converts H2O2 to H2O and O2?

Answer 14

Catalase

Question 15

What is the typical pH maintained in the cell?

Answer 15

Typically 7

Question 16

What is the pH range for neutrophiles?

Answer 16

Live and multiply from 5-8

Question 17

What is the pH range for acidophiles?

Answer 17

Below 5.5

Question 18

When might you find neutrophiles?

Answer 18

In gut bacteria. They have unique mechanism to change pH.

Question 19

What is the pH range for alkalophiles

Answer 19

Above 8.5

Question 20

What do all microbes require for growth?

Answer 20

Water

Question 21

How can microbes survive and multiply in very high salt concentrations?

Answer 21

By increasing the solute concentration inside the cell.

Question 22

What are osmotolerant bacteria?

Answer 22

Those tolerant of high salt environment. (Up to 10%)

Question 23

What are halophiles?

Answer 23

Require high levels of salt to live and multiply (more than 10%)

Question 24

What two ways can microbes increase solute concentration inside the cell?

Answer 24

• pump ions (most often K+) from outside to inside

- synthesize small organic compounds that have no effect on normal cellular activity (often proline)