Identification of a C25 highly branched isoprenoid triene in the freshwater diatom Navicula sclesvicensis

The first example of a freshwater diatom species that biosynthesises the widespread organic geochemicals known as highly branched isoprenoids (HBIs) is identified. As a result, diatoms known to produce HBIs now include benthic, planktonic, marine and freshwater species. Laboratory cultures of a number of freshwater diatoms isolated from Swanpool, UK and Paimpont, France were examined for highly branched isoprenoid (HBI) alkenes. A C25 HBI triene was identified in Navicula sclesvicensis, and characterised using GC–MS, by comparison with an authentic standard.