Fig. 1: Genomic mining of GV gene clusters reveals homologs with non-linear ultrasound contrast in E. coli.
a, 16S phylogenic tree of known GV-producing organisms, with the species from which GV genes were cloned and tested in this study indicated by name. See Supplementary Fig. 1 for the fully annotated phylogenic tree. B. megaterium and S. coelicolor were not reported to produce GVs, but we tested their GV gene clusters here based on previous expression of B. megaterium GVs in in E. coli38 and to broadly sample the phylogenetic space by including an actinomycete. b, Workflow for testing GV clusters. Selected GV gene clusters were expressed in BL21(DE3) E. coli by growing patches of cells on plates containing the inducer IPTG, and the patches were then imaged with non-linear ultrasound (xAM). c–e, Diagrams of the GV gene clusters tested in E. coli (c), differential xAM images of representative patches (d) and quantification of the differential xAM signal-to-background ratio (SBR) of the patches (n = 6 biological replicates) (e). f,g, Representative xAM images (f) and quantification of the xAM SBR (n = 3 biological replicates, each with two technical replicates; lines represent the mean) (g) for the top five GV-producing clusters expressed in E. coli at 30 °C on solid media and normalized to 5 × 109 cells per milliliter in agarose phantoms, imaged at 1.74 MPa. See Extended Data Fig. 2a,b for the ultrasound signal at varying acoustic pressures and Extended Data Fig. 2c for the corresponding BURST data.
