Changes in optical density of cultures with <i>S. thermophilus</i> and low initial densities of WT phage.

<p>The first transfer was initiated with 40 µl of an overnight culture of bacteria (approx. 2×10⁶ cells per ml) and WT phage (approx. 2×10⁴ ml) in 4 ml LM17Ca medium. The second transfer was initiated by adding 40 µl of the 24-hour first-pass cultures to 4 ml fresh LM17Ca. Panel A: WT phage with WT cells (medium-weight blue line) and 10 first-order BIMs. Panel B: WT phage with five second-order BIMs. The heavy black lines with square tick marks are phage-free WT controls. The heavy red lines with diamond tick marks are the arithmetic mean densities of all BIM cultures with phage.