To increase P density in the model cyanobacteria PCC 7002, we chose to focus on maximizing phosphate import, which is under tight genetic control. As shown in Figure , there are two main phosphate transporters in bacteria: the high-affinity low-rate pstSCAB system and the low-affinity high-rate pit system. Both systems are generally controlled by the pho regulon, which manages the global response to phosphate conditions. pstSCAB is typically active in low phosphate conditions and pit is generally either constitutively active or expressed only in high phosphate conditions. Phosphate uptake is tightly controlled, and our first objectives were to remove native regulation and increase expression of both phosphate transporters.