This disclosure provides compositions and methods for culturing microorganisms. The disclosure includes mixtures of different microorganisms, especially mixtures of cyanobacteria with fermentative microorganisms. For example, methods and compositions related to co-cultures of yeast and cyanobacteria are provided. Also provided are feedstocks derived from cyanobacteria as well as methods of making such feedstocks and methods of culturing microorganisms in such feedstocks.