Mbio Microbial Growth & Metabolic Diversity Exam 3, Lesson1

Front 1

What is microbial growth?

Front 2

For microbial growth... 2 types of requirements

Back 2

______ requirements: Temperature pH Osmotic pressure

______ requirements: Types of nutrients, Growth factors

Front 3

For Microbial Growth (3 Choices)

Back 3

1.

2.

3.

Front 4

Physical Requirements for Microbial Growth - Temperature

Back 4

Temperature

the internal temperature of a microorganisms is the same as that of the environment they are in

not all microorganisms grow within the same temperature range

Front 5

Minimum growth temperature

Back 5

the lowest temperature that a microbe can grow at

Front 6

Optimal growth temperature

Back 6

the temperature at which the microbe grows best

Front 7

Maximum growth temperature

Back 7

the highest temperature that a microbe can grow at

Front 8

Physical Requirements for Microbial Growth - Temperature

Back 8

Temperature

Together, the minimal, optimal & maximal growth temperatures of a microbe are referred to as its: ________ temperatures

Front 9

Microbes can be divided into 3 groups based on their preferred temperature range:

Back 9

Psychrophiles (cold-loving microbes)

Mesophiles (moderate temp-loving microbes)

Thermophiles (heat-loving microbes)

Front 10

Strict psychrophiles

Back 10

cannot grow above room temperature

Front 11

Psychrotrophs

Back 11

cannot grow above 40*C ("food spoilage" microbes)

Front 12

Mesophiles

Back 12

moderate temperature-loving microbes

optimal growth temp between 25- 40*C

Front 13

What microbes fall into the Mesophiles category?

Front 14

Why do we keep food in the refrigerator?

Back 14

- At 0-4*C most ________ microbes cannot survive/grow and food spoilage microbes grow slowly

-Above 4*C many bacteria can survive and/or grow

Front 15

Why do we cook food?

Back 15

- Slow growth and/or destruction of most types of bacteria (including ______)

- Rapid growth of many types of bacteria (including ______)

Front 16

Thermophiles

Back 16

heat-loving microbes

- optimal growth temperature between 50-60*C many cannot live at temperature below 40*C

- Core body temperature is 37*C, so Thermophiles are generally not considered a public health concern.

Front 17

Hyperthermophiles

Back 17

have an optimal growth temperature > or = 80*C

Front 18

pH

Back 18

potential of hydrogen (H+)

Front 19

If more H+ than OH-

Back 19

More acidic ( 0-6ish )

Front 20

If H+ equals OH-

Back 20

Neutral ( [H+] = [OH-] )

= 7

Front 21

If more OH- than H+

Back 21

More basic ( 8-14ish )

Front 22

Examples of certain pH's on a pH scale

Back 22

0

1 - Stomach acid

2 - Lemon juice

3

4 - Wine

4.5 - Tomato juice

5

6 - Urine

6.5 - Milk

7 - Pure water

7.5 - Human blood

8

8.5 - Seawater

9

10

10.5 - Milk of magnesia

11

12

12.5 - Household bleach

13

13.5 - Oven cleaner

14 - Limewater

Front 23

Physical Requirements for Microbial Growth - pH

Back 23

For optimal growth of MOST bacteria pH 6.5-7.5

Front 24

Most ______ bacteria are neutrophiles

Front 25

Acidophiles

Back 25

- can survive and grow under acidic conditions

- Example - Helicobacter pylori

- associated with stomach ulcers and

stomach cancer

Front 26

Acidic lake in the Danakil Desert Ethiopia = pH

Back 26

pH 1

Front 27

Acid mine drainage = pH

Back 27

pH 5

Front 28

Alkaliphiles

Back 28

- can survive and grow under alkaline/basic conditions

- Example - Bacillus alcalophilus - can grow at

pH 8-10

Front 29

Soap Lake, Washington = pH

Back 29

pH 9.7

Front 30

Slag Dumps around Lake Calumet, Illinois = pH

Back 30

pH 12.8

Front 31

Physical Requirement for Microbial Growth -

Osmotic Pressure

Back 31

- bacteria require H2O for growth

- bacteria obtain nutrients dissolved in H2O around them

- bacteria are "bags of water" (80-90% H2O)

Front 32

most environments bacteria will encounter will be...

Back 32

isotonic environments

(especially true for ______)

*solute concentration outside the cell is equal to that inside the cell - H2O exchanged equally

Front 33

If solute concentration outside the cell is greater than the solute concentration inside the cell...

Back 33

hypertonic environment

- water moves out of the cell

- plasmolysis occurs

- inhibition of growth and/or cell death

Front 34

______ (salt-loving microbes)

Back 34

1. Obligate ______

2. Facultative ______

Front 35

Obligate ______

Back 35

require extremely high salt concentrations

(> or = 20%) for growth and cannot survive at lower salt concentration

(e.g., Dead sea bacteria)

Front 36

Facultative ______

Back 36

can tolerate up to 15% salt but do not require a high salt concentration for growth

(e.g., Staphylococcus aureus)

Front 37

Review

What is microbial growth?

Front 38

Review

What are the two general of requirements for microbial growth?

Front 39

Review

A bacterium has just encountered a new environment. What are its three basic choices with respect to growth in this new environment?

Front 40

Review

What are a bacterium's cardinal temperatures? Do all bacteria have the same cardinal temperatures?

Front 41

Review

Define the following: psychrophiles, psychrotrophs, mesophiles, thermophiles, and hyperthermophiles. What category do most human pathogens fall into?

Front 42

Review

Defing the following: neutrophils, acidophiles, and alkaliphiles. What category do most human pathogens fall into?

Front 43

Review

With respect to osmotic pressure, what type of environment will most bacteria encounter and what happens under this condition?

Front 44

Review

What normally occurs when a bacterium is exposed to a hypertonic environment? How would exposure to this condition affect an obligate halophile or a facultative halophile and why?