Biophysical properties of mycobacteria: (a) Representative 3D reconstruction of a mycobacterial cell using Igor Pro software to calculate the volume of a single mycobacterium in air. (b) Volume of a single mycobacterium in air under different RH. The RH was adjusted by deliquescence salts inside a closed fluid chamber (n = 3 per humidity, p = 0.0008). (c) Gravimetric measurement of changes in the mass of mycobacterial pellets upon a decrease in the RH from 90% to 0% RH at 25 °C (n = 2). (d,e) Ability of soluble mycobacteria from broth cultures to survive for different periods of drying. (d) Live/dead staining using a LIVE/DEAD BacLight Bacterial Viability Kit (Invitrogen), depicted as the ratios of live vs. dead mycobacteria out of 100 mycobacteria analysed (n = 3). (e) Independent determination of CFU counts (n = 3).