Abstract: The present invention relates to nucleic acids isolated from Tetrahymena which code for a ciliate-specific triterpenoid cyclase. The inventive nucleotide sequences and the polypeptide sequences derived therefrom demonstrate a surprisingly minimal sequence identity to known isoprenoid cyclases. The invention also relates to the use of nucleic acids for the regulation of triterpenoid cyclase expression in a host organism, as well as the targeted knockout or repriming of the triterpenoid cyclase gene. As a result of the altered expression of the triterpenoid cyclase, it is possible to modify and enrich the levels of multiple unsaturated fatty acids in the host organism.

Abstract: The intention relates to a method for the fermentative production of lipids/fatty acids having high concentrations of omega-6 fatty acids (PUFA, polyunsaturated fatty acids), especially ?-linolenic acids (GLA) in ciliates. Said lipids/fatty acids can be used in human/animal food, and in the pharmaceutical field.