Transfers the 4'-phosphopantetheine moiety from coenzyme A to a Ser of an acyl-carrier-protein. Activates the peptidyl carrier protein (PCP) domains of surfactin synthas. apo-[ACP] + CoA = adenosine 3',5'-bisphosphate + H(+) + holo-[ACP] Belongs to the P-Pant transferase superfamily.