Intracellular structures in Caulobacter vibrioides

In a recent communication (Grula et al., 1954), it was demonstrated that inorganic phos-phate was involved in the genesis of the electron-opaque granules observed in Caulobacter vibrioides. However, it was not shown whether the phosphate was involved in the synthesis of ribonucleic acid, desoxyribonucleic acid, or metaphosphate. Each of the three compounds has been reported as the main constituent in what appear to be similar granules in several different organisms. Hartman and Liu (1954) implicated ribonucleoprotein in yeast cytoplasmic cell granules. Knaysi et al. (1950) observed that desoxyribonuclease digestion decreased the stain-ing potential of such granules in an avian strain of Mycobacterium tuberculosis. Konig and Winkler (1948) reported the presence of calcium phos-phate and nucleic acid in Spirillum volutans, whereas Ruska et al. (1952) implicated meta-phosphate in Mycobacteria. This paper reports further studies on the chemical nature of the granules and vacuoles of C. vibrioides. MATERIALS AND METHODS Two semisynthetic media were employed. The "A " medium (minimal phosphate) contained 1 g casein hydrolyzate2 (enzymatic), 2 mg ribo-flavin, 2 mg FeS04 77H20, and 2 g agar per 100 ml of distilled water. The "B " medium (phosphate enriched) contained 1 g casein hydrolyzate, 2 mg riboflavin, 2 mg FeSO4-7H20, 100 mg K2HP04, 100 mg KH2PO4, and 2 g agar per 100 ml of dis-tilled water. Cells transferred from nutrient agar slants were grown at 30 C for 72 to 80 hours on the "B" medium before extraction and digestion since 1 Grateful acknowledgment is expressed to El