Biosynthesis of Isoprene Units in the C34 Botryococcene Molecule Produced by Botryococcus Braunii Strain Bot-22

The colonial green alga Botryococcus braunii produces a large amount of hydrocarbons. This alga is subclassified into three chemical races (A/B/L), according to the hydrocarbon structures. Strain Bot-22 isolated from a Japanese dam is classified as race B. The main product of the strain was C34 botryococcene which was determined by nuclear magnetic resonance (NMR). The results of [1-13C] glucose feeding and NMR experiments showed that the compound was synthesized via the 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway. These results roughly agreed with a previous study. Unexpectedly, 13C-labeled methyl groups were detected in the 13C-incorporated compound suggesting that pathways besides MEP are playing a role in biosynthesis.