Lactophenol Cotton Blue: Most Widely Used Stain in Mycology



Lactophenol cotton blue (LPCB) is a widely used staining agent used in laboratories to observe chitin walled organisms (e.g. Fungi). It generally gives the specimen a blue color under microscope and helps to find them easily. It is also very simple to prepare.


This mounting medium is composed of three chemicals.

  • Lactophenol which is a mounting liquid. It carries both lactic acid (1) and phenol (2).
  • Cotton Blue (3) which helps to dye the specimen.
  1. Lactic acid preserves the fungal structure and clears the tissue.

2. Phenol, present in the first chemical kills the organisms (disinfectant behavior) and also prevent the cells from lysis. It usually deactivates the cellular lytic enzymes present in the specimen fungi.

3. Cotton blue targets the chitin present in the cell wall of the fungi and thus stain them (mainly the spores and hyphae).

Aspergillus sp. observed under Lactophenol Cotton Blue stain