Microbiology - Home ec

Section B

What are the 6 conditions necessary for the growth of microorganisms?

1. Food

2. Oxygen

3. Temperature

4. Moisture

5. pH level

6. Time

Food; Define Saprophytic

feed on non-living/dead organic matter e.g decaying plants

Food; Define Parasitic

feed on living matter/host e.g animals or humans

Oxygen; Define aerobic microorganisms 

require oxygen for growth 

Oxygen; Define anaerobic microorganisms 

do not require oxygen for growth

Oxygen; Define facultative microorganisms 

can grow with or without oxygen

Temperature; what are Psychrophilic microorganisms

grow best at low temperatures of -5 to 20 degrees

Temperature; what are Mesophilic microorganisms

grow best at medium-warm temperatures of 20 to 45 degrees (most microorganisms prefer this temp)

Temperature; what are Thermophilic microorganisms

grow best at hot temperatures of 45 to 80 degrees

Temperature; what are Hyperthermophilic microorganisms

65 - 105 degrees (very rare) 

define Moisture

all microorganisms require moisture for growth, measured in water activity

pH level; what does an acidic environment range from

1-6

pH level; what does a neutral environment range from

7

pH level; what does a basic (alkaline) environment range from

8-14

define time

all microorganisms require time to grow and multiply

Fungi do not make their own food - True or false

true

Give an example of a parasitic fungi 

athletes foot 

Give an example of a saprophytic fungi 

mushrooms on soil

what are the three type of fungi (classification?)

1. Moulds 

2. Large fungi (mushrooms)

3. Yeast 

What are the conditions for the growth of moulds

Food; saprophytic, e.g on dead organic material e.g bread and cheese - cause food spoilage

Temperature; mesophiles (20-45 degrees). Freezing inactivates moulds. Temps above 75 destroy them

Moisture; essential for growth 

Oxygen; aerobic (need oxygen), they will grow on the surface of foods e.g jam 

pH level; most like slightly acidic environments (4-6) 

Time; moulds need time to multiply (24-48 hours)