Fig. 3: Succession of a three-strain ecosystem driven by cooperation variations from labor partition.

a Design of a competitive third strain Ks. The lcnA biosynthesis pathway, including the genes lcnA, lceA, lciA, and lcmA, is placed under constitutive promoters for constant lcnA secretion. The gene gusA3 is also introduced for colorimetric quantification. b A three-strain consortium composed of Cα, Cβ, and Ks. Cα and Cβ cooperate to produce lcnG that inhibits Ks; in turn, Ks secrets lcnA to oppose Cα and Cβ. c, d Model-predicted (c) and experimentally measured (d) temporal dynamics of the Ks abundance in the Cα-Cβ-Ks ecosystem. The initial Cα:Cβ partition was varied across 30:1 to 1:30, but the total (Cα + Cβ): Ks ratio was fixed as 2:1. e Design of a control strain Kr. L. lactis MG1363 is loaded with the constitutively expressed lagC, the lcnG immunity gene, to confer resistance to lcnG and gusA3 for colorimetric quantification. f A three-strain ecosystem composed of Cα, Cβ and Kr. As Kr is deficient in lcnA production but resistant to lcnG, the consortium does not have active bacteriocin-mediated interactions. g, h Model predictions (g) and experimental measures (h) of temporal dynamics of the Kr strain in the Cα-Cβ-Kr ecosystem. The initial Cα:Cβ partition was varied across 30:1 to 1:30, but the total (Cα + Cβ): Kr ratio was fixed as 2:1. Source Data available in the source data file.