CHARACTERIZATION OF CELL-SURFACE MATERIAL REMOVED BY WATER AND NACL WASHING OF PARACOCCUS-DENITRIFICANS GROWN UNDER CONDITIONS OF DIVALENT-CATION DEFICIENCY AND SUFFICIENCY

Paracoccus denitrificans grown on complex medium deficient in Mg2+ and Ca2+ are rendered lysozyme susceptible by washing with NaCl, whereas cells grown in a succinate-salts medium (Mg2+ and Ca2+ sufficient) or complex medium supplemented with Mg2+ + Ca2+ are not. The material rel eased by water washing of cells grown on complex medium and complex me dium supplemented with Mg2+ and Ca2+ was characterized by a high prote in content. There was a high lipid: protein ratio and an appreciable a mount of 3-deoxyoctulosonic acid in the material released by NaCl wash ing of cells grown under all conditions, indicating release of outer m embrane material. The lipid ornithine: lipid phosphorous ratios of NaC l wash from cells grown on complex medium and complex medium supplemen ted with Mg2+ and Ca2+ were 0.54 and 0.34, respectively. Although NaCl washing removed outer membrane material from cells grown under all co nditions, only divalent cation deficient cells were rendered lysozyme susceptible. This might be explained by the increased outer membrane o rnithine-containing lipid to phospholipid ratio in these cells yieldin g a more permeable outer membrane.