Diatom of the Month May 2019 - Isolating Haslea: the blue diatom
Up until now we thought diatoms were all yellowish-brown. Anusuya Willis* present us a diatom with different colour: blue! Diatoms are single-celled algae characterized by ornate silica shells. Diatoms have a centric or pennate form with thousands of different shapes and sizes. One unique diatom has an additional feature that makes it stand out: it is blue. Diatom species of the genus Haslea Simonsen produce a water-soluble blue pigment called ‘ marennine ’ that make the inside of the cell vivid blue. Species of Haslea are found in benthic habitats all over the world, such as on sand and rocks on the bottom of coastal waters. These diatoms are particularly well known in France because when Haslea grows in high enough numbers within oyster ponds, its blue-pigment can be released into the seawater, or the cells can be consumed by the oysters, which causes their gills to turn green (Figure 1). These green oysters or “ huitres vertes ” are a delicacy in French...