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. 2016 Jan 27;2:15027. doi: 10.1038/npjbiofilms.2015.27

Figure 4.

Figure 4

Surfactin mediates growth inhibition and cell deformation of B. simplex. (a) Biofilm formation of B. simplex grown for 3 days on biofilm-inducing plates, in the presence or absence of ×2 of B. subtilis supernatant fraction from either the WT or srfAA mutant, eluted in 100% methanol. Scale bars represent 2 mm. (b) Fluorescence microscope images of B. simplex biofilm cells grown for 3 days in the presence or absence of ×2 B. subtilis supernatant fraction from either the WT or srfAA mutant, eluted in 100% methanol, and stained with FM1–43. (i) Control, (ii) +WT fraction, (iii) +srfAA mutant fraction. Scale bar represents 2 μm. (c) Quantification of deformed B. simplex cells in B. simplex biofilms treated with or without ×2 B. subtilis supernatant fractions from WT or ΔsrfAA mutant strains, eluted with 100% methanol. (n=5000). Error bars represent the s.d. (d) Growth curves of B. simplex in 96-well plates with shaking in MSgg. Cells were supplemented with supernatant fractions derived from either WT or srfAA mutant strains. (e) Liquid chromatography-mass spectrometry analysis of the varying tail length surfactin molecules found in the active surfactin fraction. (i) Chromatographs of surfactin standard (SIGMA S3523), (ii) chromatographs of the active surfactin fraction, (iii) mass spectrometry analysis of the varient surfactin molecules found in the active fraction.