The invention provides new compositions and methods for the production of useful chemicals from recombinant photosynthetic bacteria, such as recombinant cyanobacteria. Embodiments of the invention provide for the genetic engineering of photosynthetic bacteria to express and secrete a product of interest, such as hexose sugars or lactate. More specifically, the recombinant cyanobacteria express heterologous genes for both product expression and secretion. In some embodiments, the recombinant cyanobacteria express heterologous genes for secretion of products coupled to a pH gradient across a cell membrane. Sugars, such as sucrose, glucose and fructose, and other useful chemicals, such as lactic acid, are produced via the invention.