Figure 5: Comparing interspecies electron transfer mechanisms.

(a) Relative efficiency of the different modes of interspecies electron transfer. DIET+acetate case represents the WT strain, DIET case represents the CS K.O. strain and the hydrogen transfer case is simulated using the coculture P. carbinolicus and G. sulfurreducens. The maximum energy yield per mol of electron donor is calculated for each mode of interspecies electron transfer. The theoretical maximum for the net reaction in this consortium is 8.27. The pie charts represent the relative abundance of the interacting partners during each mode of interspecies electron transfer. (b) Relationship between community dynamics and mode of interspecies electron transfer. Simulations were carried out with a community model capable of doing hydrogen transfer and DIET. Simulations were conducted over the entire range of optimality levels of both the interacting organisms and whether DIET or hydrogen transfer occurred was monitored. The blue area represents the sole occurrence of DIET during the interaction and the orange area shows the region where DIET and hydrogen transfer occur. Interspecies hydrogen transfer occurred in addition to DIET, in regions where the optimality levels of the electron-accepting organism was at least 1.8 times that of the electron-donating organism.