A DOLMN flux solution of E. coli core carbon metabolism. A DOLMN flux solution of E. coli core carbon metabolism. The figure illustrates the solution for 2-strain communities when 11 transport reactions (TTR = 11) and 26 intracellular reactions (TIN = 26) are allowed in the E. coli core network. Intracellular metabolites that are required for growth are bolded. Exchange reactions are represented in black and show the direction of the net flux between the two strains. Flux values (in millimoles per gram cell dry weight per hour) are indicated next to the arrows signifying the reactions. Both strains grew at 0.40 h−1. Transport reactions are represented in either light orange or purple and intracellular reactions are represented in either dark orange or purple for strain x or strain y, respectively. Reactions that the algorithm identifies as excluded or that have zero flux are indicated as a hollow arrow. The tricarboxylic acid (TCA) cycle is split between the two strains. Both strains consume oxygen, glucose, phosphate, and ammonium and secrete carbon dioxide and water. The two strains exchange the TCA intermediate 2-oxoglutarate and the glycolytic intermediate pyruvate (bolded and underlined); metabolite exchange is illustrated as an orange or purple arrow to indicate which strain is producing the metabolite. Meghan Thommes et al. mSystems 2019; doi:10.1128/mSystems.00263-18