Figure 6

Minimal metabolisms from the complete universe can have many viable neighbors. (A) The horizontal axis denotes the size of minimal metabolisms and the vertical axis denotes their frequency. The average minimal metabolism comprises 352 reactions, while the largest minimal metabolism we find has 391 reactions. (B) The vertical axis shows the frequency of potential metabolisms with a given number of neighbors (horizontal axis). A minimal metabolism has 372.8 viable neighbors on average. Data in (C) show that the number of viable neighbors (vertical axis) is positively correlated with the number of reactions present in a minimal metabolism (horizontal axis). Data in (A), (B) and (C) are based on 500 minimal metabolisms generated through the random reaction deletion process described in the text.