Phosphatidylglycerol (PG) is an important component of membranes and is found in bacteria. As Streptomycetes have a large amount of the PG in their cell membranes, in this study we have focused on the gene SCO5753 (pgsA) from the model organism Streptomyces coelicolor, whose product is predicted to synthesize PG the precursor of CL. Mutations in the phosphatidylglycerol-3-phosphate synthase (PgsA) operon were introduced by using the procedure for in vitro transposon mutagenesis, and gene disruptions in the pgsA operon could not be achieved which indicated the essentiality of this operon in S. coelicolor development and growth. This gene was inserted under the control of an inducible promoter tipA, to understand the effect of over production of PG in Streptomyces. It showed poor development of growth on agar, except if provided with expression of the promoter. The importance of PG in the osmotic adaptation of wild type S. coelicolor culture was investigated. Phospholipids were extracted and the appearance of spots on thin layer chromatography plates (TLC) after separation by chloroform/methanol/acetic acid/water (80/12/15/4) showed that the proportion of PG increased during growth of these bacteria in media containing high amounts of KCl within 24 hours.