dry lima beans
fresh papaya juice
graduated cylinder (10ml)
15 ml test tube
test tube rack or 250 ml beaker
ice cold 95% ethanol
glass stirring rod
Lima Bean Bacteria Suspension:
Place 1-2 handfuls of dry lima beans in a large
jar and fill halfway to the top with distilled water.
Cover and sit in a warm room for 2-3 days.
Culturing longer than three days often results in more DNA
but it usually shears. Pour through a strainer and keep the
liquid for the extractions.
Prep buffer solution:
57 g granulated sugar
3 g epsom salts
1 buffered aspirin
add distilled water for a total volume of 500 ml
50% detergent solution:
20 ml detergent
20 ml distilled water
29.2 g non-iodized salt
add distilled water for a total volume of 250 ml
Add 14 ml of the bacterial suspension to a centrifuge tube and spin in a balanced centrifuge for 5 minutes.
Pour off the liquid (supernatant) and discard. You want to keep the pellet as this has your cells.
Add 5 ml of prep buffer and resuspend your cells with a pipet.
Add 1 ml 50% detergent solution.
Add 1 ml papaya juice.
Add 2 ml salt solution and shake for 2 minutes.
Place the tube in the centrifuge and spin for 5 minutes. Make sure the centrifuge is balanced.
Draw off 7 ml of the supernatant (liquid) as this has the DNA and place it in a clean test tube.
Pour 7 ml of ice cold ethanol carefully down the side of the tube.
Let the mixture sit undisturbed 2-3 minutes until the bubbling stops.
The DNA will float in the alcohol. Swirl a glass rod at the interface of the two layers. You may see some tiny threads of DNA but are more likely to see fluffy, white sheared DNA.
Modified from: "Generic, All Purpose DNA Extraction from Meat Protocol" Judy Brown
"Mammalian DNA Extraction" Theresa Knapp