Catalyzes the reversible phosphatidyl group transfer from one phosphatidylglycerol molecule to another to form cardiolipin (CL) (diphosphatidylglycerol) and glycerol. 2 1,2-diacyl-sn-glycero-3-phospho-(1'-sn-glycerol) = a cardiolipin + glycerol Localized in the septal membrane. Localization depnds on FtsZ. Cells lacking this gene show a lack of cardiolipin (PubMed:14973018). Cells appear normal, no effect on flotillin cluster numbers or size (PubMed:27362352). Belongs to the phospholipase D family. Cardiolipin synthase subfamily.