We study the effect of background fluxes of general Hodge type on the
supersymmetry conditions and on the fermionic zero modes on the world-volume of
a Euclidean M5/D3-brane in M-theory/type IIB string theory.
Using the naive susy variation of the modulino fields to determine the number
of zero modes in the presence of a flux of general Hodge type, an inconsistency
appears. This inconsistency is resolved by a modification of the supersymmetry
variation of the modulinos, which captures the back-reaction of the
non-perturbative effects on the background flux and the geometry.Comment: 21 pages, revised version contains a new appendix on dimensional
reduction of spinors and some changes in the spinor equation