DEVELOPMENT OF A SIMPLE CHEMICALLY-DEFINED MEDIUM FOR PORPHYROMONAS-GINGIVALIS - REQUIREMENT FOR ALPHA-KETOGLUTARATE

The aim of this study was the development of a simple, defined medium for the growth of laboratory and clinical isolates of Porphyromonas gi ngivalis. A medium was designed in which the carbon and nitrogen requi rements were provided by a single protein source - bovine serum albumi n. High cell yields were achieved in this medium but growth was accomp anied by a heavy blackening of the cells due to the deposition of meta l sulfide(s), most probably iron(II) sulfide, at the cell surface. Goo d growth in the absence of blackening was achieved when the iron salt in the medium was substituted with alpha-ketoglutarate, The resultant alpha-ketoglutarate/BSA medium was able to support the growth of all l aboratory and clinical P. gingivalis strains examined and should prove useful in the investigation of the physiology and nutritional regulat ion of virulence of this organism.