Compute density of dry weight at OD=1 as ((wb - wbt) - (wm - wmt))/(OD*V),
- wb is the weight of the tube with the dried bacterial residue (measured in step #8)
- wbt is the weight of the same tube, but clean (measured in step #3)
- wm is the weight of the tube with the dried M9 residue (measured in step #8)
- wmt is the weight of the same tube, but clean (measured in step #3)
- OD is the optical density of the bacterial suspension (measured in step #5)
- V is the volume that was added to the vials in step #6 (5 mL)