  Hypothetical models have been proposed in which explicit collapse mechanisms
prevent the superposition principle to hold at large scales. In particular, the
model introduced by Ellis and co-workers [Phys. Lett. B ${\bf 221}$, 113
(1989)] suggests that quantum gravity might be responsible for the collapse of
the wavefunction of massive objects in spatial superpositions. We here consider
a recent experiment reporting on interferometry with atoms delocalized over
half a meter for timescale of a second [Nature ${\bf 528}$, 530 (2015)] and
show that the corresponding data strongly bound quantum gravity induced
decoherence and rule it out in the parameter regime considered originally.
