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OBTAINING A PURE CULTURE
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Pure culture
Culture growing are only ONE species of cells; originated from ONE cell
Plating
Process of spreading bacterial culture onto petri dish to isolate colonies
Supplies for plating
Agar plate
Culture
Sterile loop/swab/needle/wire/L-shaped rod
Incubator (37 degrees Celsius)
***Tools & environment MUST be sterilized
Four-phase dilution
[P1] > [P2] > [P3] > [P4]
***# of phases can inc OR dec depending on culture concentration OR seterile loop can be passed through previous quadrant multiple times
After streaking, samples INVERTED and incubated at 37 degrees C
***Temp & time can be varied to optimize generation time & restrict/enhance certain microbial growth
![<p>[P1] > [P2] > [P3] > [P4]</p><p>***# of phases can inc OR dec depending on culture concentration OR seterile loop can be passed through previous quadrant multiple times</p><p>After streaking, samples INVERTED and incubated at 37 degrees C</p><p>***Temp & time can be varied to optimize generation time & restrict/enhance certain microbial growth</p>](https://assets.knowt.com/user-attachments/e679841e-ad60-4db9-b8ed-00954a64cb28.png)
Generation time
Time it takes for bacteria to divide/double
Quadrant Growth Plate
Tests multiple cultures; will they grow on plate with specified conditions?
Spread plate
Bacterial culture is serial diluted
Dilute culture is spread on surface of agar by L-shaped agar & placed on turntable
Uniformly spread
Goal: Spread single cells across surface
Pour plate
Culture serial diluted in broth
When poured onto petri dish, mix culture with warm agar
Mixture & agar solidifies together
Result: Colonies grow THROUGHOUT agar
Primary advantage of agar plating
Cells are held in place to support formation and visualization of colonies
Skin specimen collection method
Sterile swab brushed on surface
Blood specimen collection method
Needle aspiration from vein; anticoagulants included in specimen tube
Cerbrospinal fluid specimen collection method
Needle aspiration from subarachnoid space of spinal column
Stomach specimen collection method
Intubation often via nostril
Urine specimen collection method
Aseptic: catheter is inserted into bladder through urethra
Clean catch: Initial urination washes urethra, THEN specimen is midstream urine
Lungs specimen collection method
Collection of sputum either by coughing or via catheter
Diseased tissue specimen collection method
Surgical removal (biopsy)