Table 1. Approximation of the scattering contrasts at 12.8 keV derived from literature data on elementary composition and density.

The density and elemental composition of a whole bacterial cell were calculated from the dry mass composition (Duboc et al., 1999 ▸) and the water content (Neidhardt & Curtiss, 1996 ▸). The elementary compositions of DNA and ribosomes were calculated from their structure. All contrasts are given relative to H₂O. (Density: 1 g ml⁻¹; |Δρ|² to vacuum: 88.73 × 10²⁰ cm⁻⁴.) The calculations were performed using the scattering contrast module of the IRENA macros (Ilavsky & Jemian, 2009 ▸) for Igor Pro.

Component	Density (g ml−1)	Approximated element composition	Scattering contrast |Δρ|2 (cm−4)
Proteins	1.35 (Fischer et al., 2004 ▸)	NC5O2H8	7.983 × 1020
DNA	2 (Feijó Delgado et al., 2013 ▸)	PN5O7C10H14	66.82 × 1020
Ribosomes	1.62 (Fenwick, 1971 ▸)	PN5O8C10H14	30.20 × 1020
E. coli cell	1.1 (Duboc et al., 1999 ▸)	C0.09H0.61O0.27N0.019 (Duboc et al., 1999 ▸; Neidhardt & Curtiss, 1996 ▸)	0.650 × 1020