For each alga:

1. 2 grams of powder alga were added into a 1.5 ml Eppendorf tube containing 750µL acidic water (pH 4).
2. The tubes were centrifuged at 7500 rpm at room temperature for 2 minutes to wash off the polysaccharides covering the algae.
3. After decantation of the supernatant this procedure was repeated. 100 µL of buffer (25nM NaOH/0.2mM EDTA) were added to the washed algae powder and the mixture was centrifuged.
4. After decantation, the tubes were dipped in liquid nitrogen for 30 seconds and transferred for into a heating block 10 minutes, pre-heated to 99°C.
5. The tubes were then cooled to room temperature and 100 µL of buffer (40 mM tris HCl pH 5.5) were added.
6. Finally, the tubes were centrifuged at 14,000 rpm for 2 minutes. At this stage, the DNA was present in the supernatant, which was transferred into new 1.5 ml Eppendorf tubes.