Lab 12: Environmental Influences on Bacterial Growth

Question 1

What are the 4 abiotic conditions that affect microbial growth?

Answer 1

1) Temperature
2) pH
3) Osmotic pressures
4) Oxygen

Question 2

Define psychrophile, mesophile, and thermophile

Answer 2

1) Psychrophile: Thrive at 14 degrees celsius (cold) (10<14<20)
2) Mesophile: Thrive at 37 degrees celsius (moderate) (15<37<40)
3) Thermophile: Thrive at 68 degrees celsius (hot) (44<68<72)

Question 3

1) Define halophiles
2) What percentage do they like?

Answer 3

1) Organisms that like high-salinity (NaCl)
2) .4% < 3% < 8-9%

Question 4

1) What pH is the human body?
2) What pH do acidophiles like?
3) What pH do alkaliphiles like?

Answer 4

1) 7
2) <2
3) 9-11

Question 5

Describe what was done in the pH experiment

Answer 5

1 tube of each bacteria (Sc, Sa, Ec, Bc, Ef) was placed at 37 degrees at each pH level (4,7,9)

Question 6

1) Define microaerophiles
2) Define capnophiles
3) What percentage of oxygen is in the atmosphere?
4) What percentage of oxygen is in a Brewer’s jar?
5) What percentage of oxygen is in a candle jar?

Answer 6

1) Require less oxygen than air
2) Require increased CO2
3) 21%
4) 0%
5) 6-8%