  Grand unification groups (GUTs) are constructed from SO(32) heterotic string
via $\Z_{12-I}$ orbifold compactification. So far, most phenomenological
studies from string compactification relied on $\EE8$ heterotic string, and
this invites the SO(32) heterotic string very useful for future
phenomenological studies. Here, spontaneous symmetry breaking is achieved by
Higgsing of the anti-symmetric tensor representations of SU($N$). The
anti-SU($N$) presented in this paper is a completely different class from the
flipped-SU($N$)s from the spinor representations of SO($2N$). Here, we realize
chiral representations: $\tsix\oplus 5\cdot\nineb $ for a SU(9) GUT and
$3\{{\ten}'_L\oplus {\fiveb}'_L\}$ for a SU(5)$'$ GUT. In particular, we
confirm that the non-Abelian anomalies of SU(9) gauge group vanish and hence
our compactification scheme achieves the key requirement. We also present the
Yukawa couplings, in particular for the heaviest fermion, $t$, and lightest
fermions, neutrinos. In the supersymmetric version, we present a scenario how
supersymmetry can be broken dynamically via the confining gauge group SU(9).
Three families in the visible sector are interpreted as the chiral spectra of
SU(5)$'$ GUT.
