  The universal entropy bound of Bekenstein is considered, at any strength of
the gravitational interaction. A proof of it is given, provided the considered
general-relativistic spacetimes allow for a meaningful and inequivocal
definition of the quantities which partecipate to the bound (such as system's
energy and radius). This is done assuming as starting point that, for assigned
statistical-mechanical local conditions, a lower-limiting scale l* to system's
size definitely exists, being it required by holography through its
semiclassical formulation as given by the generalized covariant entropy bound.
An attempt is made also to draw some possible general consequences of the l*
assumption with regards to the proliferation of species problem and to the
viscosity to entropy density ratio. Concerning the latter, various fluids are
considered including systems potentially relevant, to some extent, to the
quark-gluon plasma case.
