Phosphodiesterase (PDE) that catalyzes the hydrolysis of cyclic-di-GMP (c-di-GMP) to 5'-pGpG (By similarity). Overexpression reduces biofilm formation. Cyclic-di-GMP is a second messenger which controls cell surface-associated traits in bacteria (PubMed:19460094). cyclic di-3',5'-guanylate + H2O = 5'-phosphoguanylyl(3'->5')guanosine + H(+) Cells lacking this gene have a weak reduction in swarm size.