Microbial Growth

Question 1

Important for energy and construction

Answer 1

microbial nutrition

Question 2

substances used in biosynthesis energy production

Answer 2

nutrients

Question 3

Biochemical Components of Cells

Water-
Protein-
Nucleic acid-
Lipid-

Answer 3

Water-80%
Protein- 40-70%
Nucleic acid- 13-34%
Lipid-10-15%

Question 4

Refers to an increase in cell number, not in cell size.

Answer 4

microbial growth

Question 5

Bacteria grow and divide by _______ a rapid and relatively simple process.

Answer 5

binary fission

Question 6

“Cold-loving”. Can grow at 0oC

Answer 6

Psychrophiles

Question 7

Psychrophiles two groups

Answer 7

True Psychrophiles
Psychrotrophs

Question 8

Sensitive to temperatures over 20oC. Optimum growth at 15oC or below. Found in very cold environments (North pole, ocean depths). Seldom cause disease or food spoilage.

Answer 8

True Psychrotrophs

Question 9

Optimum growth at 20 to 30oC. Responsible for most low temperature food spoilage.

Answer 9

Psychrotrophs

Question 10

Requirements for Growth
Physical Requirements

Answer 10

Temperature
pH
Osmotic Pressure

Question 11

Middle loving”. Most bacteria.

Answer 11

mesophiles

Question 12

include most pathogens and common spoilage organisms.

Answer 12

mesophiles

Question 13

Mesophiles best growth between

Answer 13

25° to 40°C

Question 14

mesophiles optimum temperature commonly is

Answer 14

37°

Question 15

Heat loving

Answer 15

thermophiles

Question 16

Thermophiles optimum growth is

Answer 16

50° to 60°C

Question 17

Adapted to live in sunlit soil, compost piles, and hot springs.

Answer 17

Thermophiles

Question 18

Optimum growth at 80oC to 140o C. Archaebacteria. Most live in volcanic and ocean vents.

Answer 18

extreme thermophiles (hyoerthermophiles)

Question 19

Most bacteria prefer _____ pH (6.5-7.5)

Answer 19

neutral

Question 20

_____ and ____ grow in wider pH range, but prefer pH between 5 and 6.

Answer 20

molds and yeast

Question 21

inhibits most microbial growth and is used frequently for food preservation

Answer 21

acidity

Question 22

inhibits microbial growth, but not commonly used for food preservation

Answer 22

alkalinity

Question 23

inhibits microbial growth, but not commonly used for food preservation

Answer 23

alkalinity

Question 24

“Acid loving”

Answer 24

acidophiles

Question 25

Grow at pH 5.4 to 8.5.

Answer 25

neutrophiles

Question 26

“Alkali loving”

Answer 26

alkaliphiles

Question 27

Grow at alkaline or high pH (7 to 12 or higher)

Answer 27

alkaliphiles

Question 28

High osmotic pressure removes water from cell, causing shrinkage of cell membrane (plasmolysis)

Answer 28

hypertonic solutions