Connectivity of connected bipartite graphs with two orbits

Let X = (V, E) be a simple connected graph, the connectivity kappa(X) of X is the minimum cardinality of all vertex cut sets in X. Let x is an element of V(X), the set {x(g) : g is an element of Aut(X)} is called an orbit of Aut(X), the automorphism group of X. In this note, we prove that the connectivity of a connected bipartite graph with two orbits attains its minimum degree.