Environmental Influences and Control of Microbial Growth

Question 1

Environmental Factors

Answer 1

Temperature, Oxygen, pH, Osmolarity, and Pressure

Question 2

Psychrophiles

Answer 2

optimum temperature below 15 degrees C

Question 3

Mesophiles

Answer 3

optimum temperature 20-40 degrees C

Question 4

Thermophiles

Answer 4

optimum temperature above 45 degrees C, average of ~ 60 degrees C

Question 5

Extreme thermophiles

Answer 5

optimum temperature above 70 degrees C, average of ~ 90 degrees C

Question 6

Aerobe

Answer 6

uses and detoxifies oxygen

Question 7

Anaerobe

Answer 7

does not require oxygen

Question 8

Catalase test

Answer 8

Addition of hydrogen peroxide to a streak of bacteria will show whether the microbe has catalase

Question 9

Neutrophiles (majority)

Answer 9

growth at pH 6-8

Question 10

Acidophiles

Answer 10

growth at acidic pH 0-5

Question 11

Alkalinophiles

Answer 11

growth at alkaline pH 9-14

Question 12

Halophiles

Answer 12

require high salt concentrations (hypertonic)

Question 13

Osmotolerant

Answer 13

tolerate high solution concentrations, but don’t require them

Question 14

Barophiles

Answer 14

adapted to grow at very high pressures, and rupture if pressure falls

Question 15

Barotolerant

Answer 15

organisms grow well

over the range of 145–7250 psi, but their growth falls off thereafter.

Question 16

Facultative anaerobe

Answer 16

grows with or without oxygen

Question 17

Microaerobe

Answer 17

grows in small amounts of oxygen