An integrative gene expression system has been constructed for the directional assembly of biological components in Synechocystis PCC6803. We have characterized 11 promoter parts with various expression efficiencies for genetic engineering of Synechocystis for the production of fatty alcohols. This was achieved by integrating several genetic modifications including the expression of multiple-copies of fatty acyl-CoA reductase (FAR) under the control of strong promoters, disruption of the competing pathways for poly-beta-hydroxybutyrate and glycogen synthesis, and for peptide truncation of the FAR. In shake-flask cultures, the production of fatty alcohols was significantly improved with a yield of 761 +/- A 216 mu g/g cell dry weight in Synechocystis, which is the highest reported to date.