PHOSPHATE TRANSPORT IN BACILLUS CEREUS

1. 1. Bacillus cereus accumulates phosphate against a concentration gradient by a process which is energy-dependent and exhibits a high temperature coefficient with an activation energy of over 12 kcal. 2. 2. The rate of uptake is doubled in cells which had been deprived of phosphorus for two hours. In such cells, a 'primary' pool of phosphate must be filled before esterification of phosphate begins, and the fast rate of uptake persists throughout this period. The rate of uptake falls to about one-half the fast value once the primary pool is filled. Isotope displacement experiments show that phosphate, taken up from that point in time, still passes through that pool. 3. 3. Arsenate and pyrophosphate which share the phosphate transport system in Bacillus cereus, can also fill the primary pool. 4. 4. The primary pool appears to be closely related to the external phosphate and to its transport, since it does not interact with phosphate liberated within the cell from α-glycerophosphate. © 1969.