Media/equipment/phases of growth

Growth media

substrate for bacteria to grow in or upon

3 types of media

1. complex

2. chemically defined

3. enriched

Complex media

• uses extracts from other organisms

• rich in nutrients supports wide range of growth

• ex: tryptic soy media

Chemically defined media

• pure organic & inorganic compounds added in exact amounts

• narrow range of growth

Enriched media

• media which specific nutrients are added

• blood agar & brain-heart infusion

Tryptic soy media

• general purpose media most often used

• available in broth and agar form

autoclave

used to sterilize media 

• 121 C

incubator

holds a constant temp, used to grow bacteria

tools to transfer bacteria from culture to sterile media

• inoculating loop

• inoculating needle

incinerator

used to sterilize inoculating tools

streak plate isolation

• goal is to get isolated colonies

• needed for all tests and procedures

gas pack jar

• used to create an oxygen free environment for anaerobic organisms

• Co2 replaces oxygen

Generation time

the time it takes for the bacteria population to double

• one cell into two

• genetically determined

1. Lag phase

bacterial cells are metabolically active, but have not started reproducing

2. Log phase

cells are reproducing at an exponential rate

• # cells doubles every generation time

3. Stationary phase

rate of cell reproduction is equal to the rate of cells dying

4. Death phase

cells dying off at exponetial rate

Bacterial growth curve

a. lag phase

b. log phase

c. stationary phase

d. death phase

Bacterial growth & types

increase in number of cells

• qualitative: what organism is growing

• quantitative: how much bacteria is present (# of cells)

Name this instrument

Spectrophotometer