Answer:
Co-transport.
Explanation:
Co-transport may be defined as the process of transport of two molecules across the membrane without the use of energy. Two types of co transport are symport and antiport.
The bacteria transport system import phosphate into the cell. The import of the phosphate depends on pH. Since, the import of phosphate depends on pH and does not depend on the ATPase activity. Here, the phosphate molecules can simultaneously cross the membranes.
Thus, the answer is co-transport.