A 247 000 x g particulate fraction from a moderately halophilic halotolerant bacterium incorporated [14C] glucose added as UDP[14C]glucose and 32P-labeled phosphatidylglycerol into glucosylphosphatidylglycerol. Exogenously added phosphatidylglycerol was available to the enzyme only when dispersed in a detergent, preferably Triton X-405, by sonication. The 14C- or 32P-labeled glucosylphosphatidylglycerol was degraded with phospholipase C. The water soluble product formed was isolated and identified by paper chromatography as glucosylglycerolphosphate. The system required Mg2+ or Ca2+ for activity. KCl and NaCl were inhibitory even when added at low concentrations.