Chapter 9 – Microbial Growth

Question 1

Psychrophiles

Answer 1

-7-19 C max growth 13 C

Question 2

Psychrotrophs

Answer 2

0-30 C max growth 22 C

Question 3

Mesophiles

Answer 3

10-47 C max growth 37 C

Question 4

Thermophiles

Answer 4

40-72 C max growth 62 C

Question 5

Hyperthermophiles

Answer 5

67-110 C max growth 95 C

Question 6

Food preservation danger zone temp

Answer 6

15-53 C

Question 7

pH range for most bacteria

Answer 7

6.5-7.5

Question 8

pH range for mold and yeast

Answer 8

5-6

Question 9

Define plasmolysis

Answer 9

shriveling of the cell plasma membrane caused by a hypertonic solution.

Question 10

capnophiles

Answer 10

microbes that require high CO2 levels…Candle Jar

Question 11

Direct methods for assessing microbial growth

Answer 11

Plate counts, Filtration, Most probably number (MPN), Direct microscopic count

Question 12

Indirect methods for measuring microbial growth

Answer 12

Turbidity, metabolic activity, dry weight

Question 13

list the phases of microbial growth

Answer 13

Lag phase, growth (log) phase, stationary phase, death phase.

Question 14

Describe bioflims

Answer 14

• microbial communities,
• form slime or hydrogels
• share nutrients
• sheltered from harmful factors