Fig. 5

HPLC–MS analysis of metabolite profiling of the ethyl acetate extract of cell-free filtrate of X. neamatophila YL001 under different initial pH. A Comparison of base peak chromatograms of X. nematophila YL001 at pH 5.5 (up), 7.0 (middle) and 8.5 (down). B LC–MS/MS analysis detecting the metabolites in the ethyl acetate extract of cell-free filtrate of X. nematophila YL001 (Additional file 1: Figures S2–S4). Peak 1, nematophin, m/z 273.15 [M+H]⁺; peak 2, Indole derives, m/z 259.14 [M+H]⁺; peak 3, Indole derives, m/z 275.16 [M+H]⁺; peak 4, indole derives, m/z 261.12 [M+H]⁺; peak 5, rhabduscin, m/z 333.00 [M+H]⁺