NUTRITIONAL REQUIREMENTS FOR BACTERIAL CELL WALL SYNTHESIS

Abstract

In the preceding paper (Shockman et al., 1961) the lytic properties of exponentially growing cells of Streptococcus faecalis have been described. Not only will washed and transferred exponential cells lyse but, under proper conditions, they eaD engage in either exponential growth or in post-exponential cell wall synthesis. Some of the necessary conditions, and evidence for the synthesis of cell wall substances will be presented here. MATERIALS AND METHODS Methods of growth, washing, and transfer of S. faecalis (ATCC 9790) were similar to those previously described (Shockman et al., 1961). However, for the experiments reported here, an increase in turbidity was expected during the second incubation, so that a starting adjusted optical density of about 400 (0.16 mg/ml) was used. In addition, larger amounts of log cells were grown in 100 to 250 ml of medium in 300-or 500-ml Erlenmeyer flasks equipped with a side arm to fit a Coleman model 14 spectrophotometer for direct reading of turbidity. These were harvested and washed as indicated above and then samples of washed cells were placed in other flasks for the secondary incubation period (see below). These cells were harvested, washed, and disintegrated by shaking with 0.2 mm diameter glass beads (Kolb, 1960) in the shaker head of an I