TABLE 4.

Comparison of dry weights determined by flow cytometry with independent measurements

Organism	Measured			Computed					Computed/ measured dry wt
	Dry wt (fg/cell)a	Vol (μm3/cell)b	Buoyant density (pg/μm3)	Dry wt/ wet wtc	Wet wt (fg/cell)d	Dry wt (fg/cell)e	Vol (μm3/cell)f	mg
C. oligotrophus	35.7	0.16	1.07	0.179	199	30.7	0.186	1.023	0.86
	28.3	0.13	1.07	0.179	158	25.0	0.148	1.023	0.88
	41.3	0.25	1.055	0.141	293	37.2	0.278	1.020	0.90
	57.7	0.24	1.055	0.141	409	35.7	0.388	1.020	0.62
Marinobacter sp. strain T2	54.0	0.24	1.075	0.192	281	49.6	0.261	1.025	0.92
	46.2	0.22	1.075	0.192	240	45.5	0.214	1.025	0.98
E. coli	322	0.81	1.10	0.286	1,128	255	1.03	1.037	0.79

^aFrom equation 4 and Fig. 2. Determined by flow cytometry. 

^bDetermined with a Coulter Counter. 

^cX_dry/X_wet (equation 1), determined with measured buoyant densities and a ρ_dry of 1.39 g/cm³ for C. oligotrophus and Marinobacter sp. strain T2 and of 1.35 g/cm³ for E. coli. 

^dDry weight from flow cytometry divided by (X_dry/X_wet) from buoyant density. 

^eCoulter volume × buoyant density × (X_dry/X_wet). 

^fWet weight divided by buoyant density (equation 3). 

^gFrom equation 2.