MICROBIAL GROWTH

Question 1

Temperatures

Answer 1

Minimum growth temp. - lowest temp. at which species will grow
Optimum growth temp. - temp. at which the species grows best
Maximum growth temp. - highest temp. at which growth is possible

Question 2

Cold-loving microbes

Answer 2

Psychrophiles
0°C - 15 °C

Question 3

Most likely encountered in low-temperature food spoilage cause they grow fairly well at refrigerator temp.

Answer 3

Psychotrophs 20-30°C

Question 4

Psychotrophs do not grow well at low temperatures but they

Answer 4

Slowly degrade food

Question 5

Common method of food preservation

Answer 5

Refrigeration

Question 6

Common type of microbes

Answer 6

Mesophiles 37°C

Question 7

Moderate-temp. loving microbes

Answer 7

Mesophiles

Question 8

Mesophiles lives in

Answer 8

Adapted to live in the bodies of animals

Question 9

Optimum temp. for many pathogenic bacteria

Answer 9

20 - 40 °C

Question 10

Heat-loving microbes

Answer 10

Thermophiles

Question 11

Optimum growth temp. of thermophiles

Answer 11

50-60 °C

Question 12

Formed by thermophilic bacteria are unusually heat resistant

Answer 12

Endospores

Question 13

Thermophiles will not grow in what temp?

Answer 13

Below 45°C

Question 14

Hot springs associated with volcanic activity and sulfur is usually important in their metabolic activity

Answer 14

Hyperthermophiles

Question 15

Optimum growth temperature of hyperthermophiles

Answer 15

80°C

Question 16

Extreme Thermophiles

Answer 16

Hyperthermophiles

Question 17

Most bacteria grow best on what pH range?

Answer 17

pH range near neutrality (7)

Question 18

Have high tolerance to acidity

Answer 18

Acidophiles

Question 19

Very few bacteria grow at what acidic pH?

Answer 19

below pH 4

Question 20

Microorganisms require water for growth, and their composition is

Answer 20

80-90% water

Question 21

Microorganisms obtain almost their nutrients in solution form the surrounding water

Answer 21

Osmotic pressure

Question 22

This osmotic loss of water causes

Answer 22

Cell shrinkage of cell’s cytoplasm

Question 23

Addition of salts or other solutes to a solution, and the resulting increase in

Answer 23

Osmotic pressure

Question 24

Can be used to preserve foods

Answer 24

Salt or sugar

Question 25

Adapted so well to high salt concentration that they actually require them for growth

Answer 25

Halophiles

Question 26

Organisms from saline waters (dead sea)

Answer 26

Obligate halophiles

Question 27

Chemical requirements

Answer 27

Carbon, nitrogen, sulfur, phosphorus and oxygen

Question 28

It is needed for all the organic compounds that make up a living cell

Answer 28

Carbon

Question 29

Important elements to synthesize cellular material

Answer 29

Nitrogen, sulfur and phosphorus

Question 30

Bacterias that use oxygen to extract more energy from nutrients

Answer 30

Aerobes

Question 31

Bacterias that does not use oxygen

Answer 31

Anaerobes

Question 32

Bacterias that requires oxygen to live

Answer 32

Obligate aerobes

Question 33

They use oxygen when it is present but are able to continue growth by using fermentation or anaerobic respiration when oxygen is not available

Answer 33

Facultative anaerobes

Question 34

Facultative anaerobes use oxygen when present but are able to continue growth by using

Answer 34

Fermentation or Anaerobic respiration

Question 35

Phases of bacterial growth

Answer 35

Lag phase - Intense activity preparing for population growth, but no increase in population.
Log phase - Logarithmic or exponential increase in population
Stationary phase - Period of equilibrium; microbial deaths balance production of new cells.
Death phase - Population is decreasing at a logarithmic rate.

Question 36

The logarithmic growth in the log phase is due to

Answer 36

Reproduction by Binary fission (bacteria) or Mitosis (yeast)

Question 37

Denotes the population of microorganisms that inhabit the skin and mucus membranes of healthy normal persons

Answer 37

Normal microbiota

Question 38

Normal microbiota provides a

Answer 38

• First-line defense against microbial pathogens
• Assists in digestion
• Plays a role in toxin degradation
• Contributes to maturation of the immune system

Question 39

Two groups of Resident Microbiota

Answer 39

Resident microbiota
Transient microbiota

Question 40

Consists of relatively fixed types of microorganisms regularly found in a given area at given age

Answer 40

Resident microbiota

Question 41

Consist of nonpathogenic or potentially pathogenic microorganisms that inhabit body sites for hours, days or weeks

Answer 41

Transient microbiota

Question 42

Microorganisms that are constantly present on body surfaces. One partner benefits, while the other seems unaffected

Answer 42

Commensals

Question 43

Both parties derive benefit

Answer 43

Mutualistic

Question 44

Significance of Normal Flora

Answer 44

• Role in maintaining health and normal function
• Can synthesize important compounds, vitamin K
• Aid in absorption of nutrients
• Prevent colonization by pathogens and possible disease

Question 45

Involve competition for receptors or binding sites on host cells, competition for nutrients, mutual inhibition by metabolic or toxic products, mutual inhibition by antibiotic materials

Answer 45

Bacterial interference

Question 46

Opportunity body to be weaker

Answer 46

Opportunistic pathogens

Question 47

Can normal microbiota cause disease?

Answer 47

Yes. If forcefully removed from the environment and introduced into the bloodstream or tissues, these organisms may become pathogenic

Question 48

What are the common resident of the Upper Respiratory Tract?

Answer 48

Streptococci viridans

Question 49

If large bumbers of Streptococci viridans are introduced into the bloodstream, they may settle on deformed or prosthetic heart valves and produce

Answer 49

Infective endocarditis