Growth by SD109 transformants producing gas vesicles is visually distinguishable from the Vac-SD109 mutant. Panels A-E show typical cultures of wild type or transformed halobacteria. Panel A: the gas vesicle deficient (GV-) strain SD109 which in natural color exhibits a characteristic rust brown appearance; Panel B: a culture of the wild type gas vesicles (GV+) from Halobacterium sp. NRC-1, exhibits the characteristic milky appearance of GV+ cultures. Panel C: a culture of transformed halobacteria strain SD109 expressing the nef1 encoded peptide exhibits the characteristic rounded morphology of GV+ cultures when plated on agar media with the slightly pink tinged white coloration. Panels D and E: Isolated recombinant gas vesicles, like the native ones are evident as a white ring at the interface of the air/5% NaCl solution. Flotation of the r-GV to this interface verifies the chimeric GV isolated from SD109 transformed with pMS104D::tat or ::nef1 are functional.