Fig. 1

Schematic representation of engineered erythritol production in Synechocystis. Erythritol can be produced with introduction of two genes, encoding an erythrose-4-phosphatase (e4P) and an erythrose reductase (er), respectively. The ER is also able to reduce erythrose-4-phosphate, as indicated with the dashed line, but whether a phosphatase is present to further process the product of this reaction to erythritol is unknown