Fig. 1

Flow chart of the experiments. The study comprised several experiments: one field experiment, three greenhouse experiments, and five in vitro experiments. In the field experiment, we investigated whether bio-organic fertilizer application changes nematode communities and enhances their abundance. From there, we isolated different anti-pathogenic bacteria and bacterivorous nematodes. We then tested the importance of the bacterivores (greenhouse expt. 1) and the microbiome (greenhouse expt. 2) in pot experiments and assessed the importance of bacterivores nematodes in co‑colonization with Bacillus for promoting plant health (greenhouse expt. 3). We also examined direct predation of bacterivorous nematodes on pathogenic R. solanacearum (in vitro expt. 1) and selective predation of nematodes on bacteria with different anti-pathogenic abilities (in vitro expts. 2–3). Finally, the co-cultural experiment validated the effects of bacterivores that promoted the expression in anti-pathogenic abilities of Bacillus, leading to a decrease of R. solanacearum (in vitro expts. 4–5)