Regulation of antimicrobial activity and xenocoumacins biosynthesis by pH in Xenorhabdus nematophila

Table 4 The relative amount of rhabduscin, nematophin and indole derivatives in ethyl acetate extract of the cell-free filtrate of X. neamatophila YL001 at pH 5.5, 7.0 and 8.5

Treatment	Relative amount of metabolites^a
Treatment	Nematophin	Indole derivative 2	Indole derivative 3	Indole derivative 4	Rhabduscin
pH 8.5	100.00	100.00	100.00	100.00	100.00
pH 7.0	63.51	93.90	63.91	91.98	10.46
pH 5.5	49.36	26.48	48.81	25.55	4.07

^aThe metabolites in ethyl acetate extract of the cell-free filtrate of X. neamatophila YL001 at different pH were identified based on LC-MS/MS in Additional file 1: Figures S2–S4, and illustrated in Fig. 5. The chromatogram peak of identified metabolites at different pH refers to Fig. 5. Relative amount of metabolites = [the peak area of extracted ion chromatograms (EIC) of metabolites at different pH/the peak area of extracted ion chromatograms (EIC) of metabolites at pH 8.5] × 100. The relative amount of metabolites at pH 8.5 refers to 100