Lab 14 culture transfer techniques isolation of pure culture Flashcards


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1

Pipettes

Instrument used to transfer aliqouts of culture, prepare serial dilutions and dispense chemical reagents

2

Two types of pipettes

Blow out pipettes/serological pipettes
To deliver pipettes/mohr measuring pipettes

3

Blow out pipettes

Final few drops of liquid must be emptied to deliver correct volume

4

To deliver pipettes

After proper amount delivered liquid will remain in the tip of pioette and should not be eliminated

5

How are pipettes sterilized

Autoclaved fast and dry cycle
Dry heat oven

6

Inoculating needles and loops

Used to skeptically transfer microorganisms from broth slant or agar cultures to other media

7

Subculturing

Microorganisms are transferred from one culture to another using specific procedures

8

Asepsis

Free from sepsis way to transfer microorganisms

9

Pure or stock culture

When bacteria transferred from center (bc less likely to b contaminated) to slant
Represents the growth of a single species of microorganism

10

Refrigeration or desiccation

Keeps microorganism in state of dormancy and minimizes need for subculturing

11

Short term maintenance

1 to 3 months of aerobic bacteria kept in fridge at 4 to 10 degrees and use of screw caps

12

Long term storage

Sealing with sterile mineral oil to stop moisture loss abut 1/4 inch above top of sant
Mineral oil can b sterilized in drying oven

13

Storage for members of enterobacteriacae (e coli and p aeru)

Can be stored for years at room temp by stab inoculating screw cap deeps with either half strength nutrient agar or .7 percent agar in distiller water, incubate overnight, screw caps down seal with tape or paraffin store at room temp

14

Lyophilization or freeze drying

Best way to preserve cultures
Culture suspended in sterile soln such as milk, serum, or 3 percent lactose
Small amounts of suspension transferred to vials and frozen in dry ice/alcohol mix
Finally dried under vacuum while still frozen and vial sealed

15

Storing anaerobes

Strict anaerobes and some facultative anaerobes
Agar stab cultures, allow tube of agar to solidify upright then inoculate to center
Anaerobes will grow deep in agar bc anaerobic conditions, then may b refrigerated
Also can be maintained in thioglycollate broth or cooked meat medium

16

Aseptic technique

Label medium to be inoculated
Shake primary culture to suspend bacteria
Put both tubes in palm of one hand to form V
Flame inoculating loop or needle along full length
Remove caps from tubes and flame necks of tubes
Cool loop or needle and pick up bacteria
Streak, put on slide, or petri plate
Reframe neck of tubes
Recap tubes
Reflame loop or needle

17

BactiCinerator sterilizer

Sterilizes needles, loops, and culture tubes in seconds, 871 Celsius
Eliminates microorganism spattering
Made of ceramic funnel tube enclosed in stainless steel perforated guard and casting support stand

18

Typical grow patterns in broth media

Growth turbid and diffuse throughout
Growth layered at surface only
Growth sedimented at bottom only
Growth layered below surface, none beneath surface
Growth forms puff balls, layered below surface