Fig. 4: Prokaryotic lineages exhibiting the most pronounced changes in the communities during the mesocosm experiments.

A–C M1, SAR11 clade (predominantly Candidatus Pelagibacter), Cyanobacteria (predominantly Prochlorococcus) and Oceanospirillales (predominantly SAR86 clade); D–F M2, SAR11 clade (predominantly Candidatus Pelagibacter), Oceanospirillales (predominantly SAR86 clade) and Thermoplasmatales (Marine Group I and III); G–I M3, SAR11 clade (predominantly Candidatus Pelagibacter), Oceanospirillales (predominantly SAR86 clade and Oceanospirillaceae) and Flavobacteriales (predominantly Flavobacteriaceae). Given are relative proportions of the lineages in the treatments with supply of B12 (red), α-ribazole (a-R, pink) and a control (C, black) at hour 3 and days 3 and 6. Significant differences of the means of a treatment and control (T-test, *p < 0.05, **p < 0.01, ***p < 0.001).