FIG 5.

Schematic of the succession of bacterial community structure and function during long-term cocultivation with Synechococcus. The initial bacterial community with a high proportion of inhibitory bacteria inhibited the growth of Synechococcus in the antagonism stage. Under the interaction between different members of the bacterial community during serial subculture, the inhibitory bacteria were suppressed to a point that they could not completely inhibit the growth of Synechococcus. The relationship between Synechococcus and the heterotrophic bacterial community gradually entered the commensalism stage. Thereafter, as the proportion of beneficial bacteria continued to increase, a mutually beneficial relationship was established between Synechococcus and the heterotrophic bacterial community. During the mutualism stage, a self-sufficient nitrogen cycle might contribute to the healthy survival of both Synechococcus and heterotrophic bacterial communities in 2 years without any exogenous nutrition supplementation.