Multi-stage synthesis process with synthesis gas

The invention relates to a process for preparing hydrocarbons substituted by at least one group containing at least one oxygen atom comprising the process steps A) reacting a carbon source comprising at least one selected from CO 2 and CO to acetate and / or ethanol with a first microorganism, B) separating the Acetate of the first microorganism, C) reacting the acetate to a hydrocarbon substituted with at least one group containing at least one oxygen atom with a second microorganism and optionally D) purifying the hydrocarbon substituted with at least one group containing at least one oxygen atom.