Almost contact structures on manifolds with a G(2) structure

We review the construction of almost contact metric (three-) struc-tures, abbreviated ACM(3)S, on manifolds with a G2 structure. These are of interest for certain supersymmetric configurations in string and M-theory. We compute the torsion of the SU(3) struc-ture associated to an ACMS and apply these computations to het -erotic G2 systems and supersymmetry enhancement. We initiate the study of the space of ACM3Ss, which is an infinite dimensional space with a local product structure and interesting topological features. Tantalising links between ACM3Ss and associative and coassociative submanifolds are observed.