Ex. 2-8; 2-9; 2-12

Question 1

cardinal temperature

Answer 1

the minimum, maximum, and optimum temperature any single species can survive within.

Question 2

psychorophiles

Answer 2

organisms that will only grow below 20 degrees Celsius with little or no fluctuation.

Question 3

psychrotrophs

Answer 3

organisms adapted to cold habitats that fluctuate from about 0 to above 30 degrees Celsius.

Question 4

mesophiles

Answer 4

organisms adapted to temperatures between 15 and 45 degrees Celsius.

Question 5

thermophiles

Answer 5

organisms adapted to temperatures above 40 degrees Celsius.

Question 6

obligate thermophiles

Answer 6

thermophiles that will not grow at temperatures below 40 degrees Celsius.

Question 7

facultative thermophiles

Answer 7

thermophiles that will grow below 40 degrees Celsius

Question 8

extreme thermophiles

Answer 8

thermophiles that can survive temperatures in the 65 and 110 degree Celsius range (up to 122 degrees Celsius for Methanopyrus)

Question 9

What temperature do extreme thermophiles grow best at?

Answer 9

above 80 degrees Celsius

Question 10

What are most bacterial residents in the human body, as well as numerous human pathogens?

Answer 10

mesophiles

Question 11

What environmental factors affect the growth rate of microbes?

Answer 11

1. temperature
2. pH
3. osmotic pressure

Question 12

What does pH stand for?

Answer 12

pondus hydrogenii

Question 13

What is Sorensen’s formula for the calculation of pH is expressed as:

Answer 13

pH = -log[H+]

Question 14

How many moles of hydrogen ions per liter does water have? What is the pH of water?

Answer 14

10 -7 moles

pH of 7

Question 15

acidophiles

Answer 15

organisms adapted to grow well in environments below about pH 5.5

Question 16

neutrophiles

Answer 16

organisms that prefer pH levels between 5.5 and 8.5

Question 17

alkaliphiles

Answer 17

organisms that live above pH 8.5

Question 18

Under natural circumstances, the majority of bacteria maintain what kind of internal environment?

Answer 18

near-neutral

Question 19

What allows the majority of bacteria to maintain their internal environment regardless of their habitat?

Answer 19

they have cytoplasmic buffers

Question 20

What can changes to pH outside an organism’s range do?

Answer 20

it may destroy necessary membrane potential (used in ATP production) and damage vital enzymes beyond repair. This denaturing my be minor but is usually lethal to the cell.

Question 21

What is the ideal pH for Alcaligenes faecalis?

Answer 21

Ideal pH 7-11

Question 22

What is the ideal pH for Lactococcus lactis?

Answer 22

Ideal pH in the range of 6.3 to 6.9, but the lower limit for growth is within the range of 4.0 to 5.0

Question 23

What is the ideal pH for Escherichia coli?

Answer 23

Ideal pH range 5-7 optimum pH is 6

Question 24

What does UV stand for?

Answer 24

ultraviolet

Question 25

Ultraviolet radiation is a type of what?

Answer 25

electromagnetic energy

Question 26

How does UV travel?

Answer 26

in waves

Question 27

How is UV distinguishable from all other electromagnetic energy?

Answer 27

by its wavelength

Question 28

What is a wavelength and what is its typical unit of measurement?

Answer 28

the distance between adjacent wave crests | measured in nanometers

Question 29

What are the three groups of UV light and their measurements?

Answer 29

1. UV-A: the longest wavelengths, ranging from 315 to 400 nm 2. UV-B: wavelengths between 280 and 315 nm 3. UV-C: the most detrimental to bacterial, wavelengths ranging from 100 to 280 nm

Question 30

What happens if a bacteria is exposed to UV-C for more than a few minutes?

Answer 30

usually results in irreparable DNA damage and death of the organism.

Question 31

What is the germicidal effect of UV-C related to?

Answer 31

- time of exposure - lamp intensity - distance to the target - "line of sight"

Question 32

What does "line of sight" refer to?

Answer 32

UV-C does not penetrate well, bend around corners, or trickle into crevices so it must have direct access to the surface being decontaminated.

Question 33

What are thymine dimers?

Answer 33

DNA lesions induced by UV rays

Question 34

As you decrease the wavelength of light, what happens to the energy?

Answer 34

it increases

Question 35

What two microbes did we use to test the effect of UV radiation? Which tolerates it better and why?

Answer 35

1. Bacillus subtilis tolerates UV radiation better because it has endospores. 2. Escherichia coli

Question 36

What temperature does Escherichia coli grow best at?

Answer 36

optimum temperature for its growth is around 37 degrees Celsius.

Question 37

What temperature and pH does Serratia marcescens grow best at?

Answer 37

Optimally, Serratia marcescens grows at 37°C, but it can grow in temperatures that range from 5–40°C. They grow in pH levels that range from 5 to 9 [14].

Question 38

What temperature does Pseudomonas aeruginosa grow best at?

Answer 38

Its optimum temperature for growth is 37°C, and it is able to grow at temperatures as high as 42°C

Question 39

What temperature does Staphylococcus epidermidis grow at?

Answer 39

Since it is a pathogen of the human skin, S. epidermidis grows best at 37°C (mesophilic), the optimal temperature for the human body.