  Mean-field electrostatics is used to calculate the bending moduli of an
electric double layer for fixed surface charge density of a macroion in a
symmetric 1:1 electrolyte. The resulting expressions for bending stiffness,
Gaussian modulus, and spontaneous curvature refer to a general underlying
equation of state of the electrolyte, subject to a local density approximation
and the absence of dipole and higher-order fields. We present results for
selected applications: the lattice-gas Poisson-Fermi model with and without
asymmetric ion sizes, and the Poisson-Carnahan-Starling model.
