Soluble metabolic products, such as ethanol, are produced by growing modified algal cells in a growth medium and recovering the products from the growth medium. The algal cells are modified to overproduce the metabolic product by providing for overexpression of at least one enzyme in the metabolic pathway for the product. For the production of ethanol, the alcohol dehydrogenase gene, the pyruvate decarboxylase gene, or both, are overexpressed, typically under the control of a heterologous promoter. The algal cells may be modified by transformation with a DNA construct including coding sequence(s) of the enzyme(s) under the control of a heterologous promoter.
