Fig. 2: Symbiotic relationship between bacteria and algae18,19,23,24,25,26,27,118.

In mutualism, bacteria and algae have complementary metabolisms and mutually benefit but the relationship is fragile; in commensalism, one party provides energy for the other to promote survival with high dependence; in competition symbiosis, bacteria and algae compete for resources inhibiting growth yet moderate competition can prompt niche differentiation, conducive to maintaining the symbiotic system’s function. This figure is independently drawn by the authors based on citation of the relevant literature.