US Patent 9068202 Fermentation process

Methods and systems for the production of one or more lipid products from a gaseous substrate using a two stage fermentation process are provided. The method comprises providing a gaseous substrate comprising CO2 and H2 to a primary bioreactor containing a culture or one or more microorganisms, and fermenting the substrate to produce an acid such as acetate. The acid, e.g. acetate from the primary bioreactor is then provided to a secondary bioreactor, where it is used as a substrate for fermentation to lipids by one or more yeasts.