Exercise 16 - Effects of Temperature on Growth

The bacterium Legionella is considered a thermophile and causes which type of disease?

Respiratory Disease

Enzyme activity and structure can determine a bacterium's sensitivity to...?

> Temperature

> pH

> Oxygen Levels

> Available Nutrition

How does a substrate interact with an enzyme?

Substrates bind to the enzyme's active site.

What are the consequences of exposing bacteria to temperatures above or below their optimal range?

Their enzymes can temporarily lose function or become denatured, entirely losing function.

A thermolabile enzyme cannot withstand temperatures ____ its optimal temperature.

above

If an enzyme can withstand high temperatures without permanent damage, they are considered...?

thermostable

Lower-than-optimal temperatures typically ____ the rate of enzymatic activity.

reduce

What are the three thermal classifications for bacteria?

1 Psychrophile

2 Mesophile

3 Thermophile

Psychrophiles or cold-loving bacteria can live at temperatures of ____ to ____.

5°C

20°C

The bacterium, ____ is considered a psychrophile and can typically populate in the refrigerator.

Listeria monocytogenes

What are the two categories of mesophiles? (hint. in reference to temperature)

> Room Temperature (20°C-35°C)

> Body Temperature (35°C-45°C)

Where do room-temperature mesophiles typically propagate?

- Plants

- Ruminating Animals

Give an example of where thermophiles are typically found (hint. they survive in environments with temperatures of 45°C and higher.)

- Hot Springs

- Hydrothermal Deep Sea Vents

TAQ polymerase, which comes from thermophiles, is considered a ____ enzyme.

thermostable

Which bacterium was used as an example of a psychrophile during Exercise 16?

Pseudomonas fragi

Which bacterium is a room-temperature mesophile and produces a red pigment at room temperature?

Serratia marcescens

What thermo-classification is Geobacillus stearothermophilus?

Thermophile

What was the purpose of Exercise 16?

To distinguish between four types of bacteria based on their thermal classification by exposing them to different temperatures (5°C, 25°C, 37°C, and 55°C).

What 2 bacteria survived incubation at 55°C?

1 G. stearothermophilus

2 E. coli

What difference was observed when Serratia marcescens was inoculated at 25°C compared to 37°C?

- At 25°C a red color was produced.

- At 37°C a yellow color was produced.

Pseudomonas fragi exhibited growth at all tested temperatures except at which temperature?

55°C

What is the optimal temperature range for E. coli?

35-40°C