Aniline blue staining
Prepare 20 ml of 8 N NaOH from sodium hydroxide pellets in double distilled water (A. bidest.) in a 25 ml beaker.
Prepare 50 ml of Sørensen’s phosphate buffer (0.1 M, pH = 8.0).
Transfer algae to 2 ml Eppendorf tubes (Figure 1B) and wash them once with culture medium.
Note: Washing can be omitted if algae from lab cultures are investigated. Avoid mechanical stress or damage to the cells by using a pair of fine-pointed tweezers. This prevents additional short-term incorporation of callose in the cell walls. Single-celled organisms or cells surrounded by a sticky mucilage layer can be transferred easily by using glass pipettes.
Decant and discard culture medium and add 1.5 ml 8 N NaOH in the tube (Figure 1C).
Note: Centrifuge at ~1,000 x g to sediment biomass in order to remove liquid.
Incubate the tubes at 60 °C for 20 min.