Fig. 6

Ca. D. californiensis beta-lactone biosynthesis. a Schematic of the DCB gene cluster. b–e Metabolite profiling studies on D. fulva skin. NMR spectrum and expansion of the NMR spectrum in CD₃OD collected from the acetone extract of Df07 and Df08. Note the minor differences in these two spectra. A structure of the putative DCB product is provided along with peak assignments by colored circles or squares. f A ¹H,¹H-COSY spectrum of the acetone extract of Df07. Correlations between the peaks (colored circles) supported the assignment of each of the four peaks. g A ¹H,¹³C-HSQC spectrum of the acetone extract Df07 skin. Correlations identify the ¹³C chemical shift for the four identified peaks allowing assignment of a putative structure for DCB. h Flow cytometry bi-plot of recombinant Aeromonas piscicola with CRAGE-inserted DCB cluster labeled with the KC-12 probe and the two negative controls: the same strain stained with the NC probe and the wild type stained with KC-12 probe. Only the combination of the CRAGE strain incubated with the KC-12 probe produced fluorescence (2nd plot). Flow cytometry plots axes are on log scale, x-axis shows side scatter signal and y-axis blue fluorescence of the probes