Lysobacter enzymogenesOH11 andBacillus safensisZK-1 showed different antimicrobial spectra. (A) ZK-1, but not OH11, showed antagonistic activity against P. syringae pv. actinidiae (Psa). M228 and C48 are two Psa strains isolated in China. (B) The killing effect of OH11/ZK-1 co-cultured with Psa on agar plates. When mixed with Psa, both OH11 and ZK-1 inhibited Psa growth, whereas the T4SS-defective mutant of OH11 (ΔvirD4) failed to kill Psa. M228 and C48 were labelled by GFP. Bacteria were mixed at a ratio of 1:1 on LB plates. Fluorescence signals were observed after 2 days of incubation. (C) OH11 showed antagonistic activity against kiwifruit pathogenic fungi D. actinidiae, C. gloeosporioides and A. alternata, whereas ZK-1 showed weak antagonistic activity against these fungal pathogens. (D) Inhibition of fungal conidia germination by co-culturing conidia with OH11/ZK-1 cells on agar plates. When mixed with fungi conidia, both OH11 and ZK-1 inhibited the transfer of conidia to the fungal mycelium of C. gloeosporioides and A. alternata.