Cyanobacteria have been used to synthesize isotopically labelled compounds such as sugars, lipids and amino acids, which are nowadays commercially available (Patterson 1996). This is achieved by growing the cyanobacetria in photobioreactors and allowing them to photosynthetically transform simple labelled compounds such as 14CO2, 13CO2, 33H2O and 15NO3 into complex organics.