Growth and gas vesicle production of H. salinarum NRC-1 and the tbpD non-native expression mutant strains. (A) A comparison of growth curves for wild-type H. salinarum NRC-1 and the nonnative tbpD expression strain. Optical density measured at 600 nm (OD600) is reported for two replicate flask growth cultures for each strain. Severe growth retardation is evident in the nonnative tbpD expression strain. (B) Growth versus gas vesicle production in wild-type cells and the nonnative tbpD expression mutant is shown as measured by OD600 and median pixel intensity for the cellular population, respectively. An increase in gas vesicle production is noted in wild-type cells that is absent in the tbpD mutant.