KLK4 and infection: The dramatic impact on phage infection kinetics with a lack of P in the medium on those cyanophages that do not possess pstS (Fig. 2A and C, Supplementary Table 3) points toward a distinct molecular mechanism, either controlled by the host or the phage, by which the infection process is delayed, and the burst size reduced, despite still maintaining similar DNA replication rates (Fig. 3A and C).