Phage adsorption assay.

A culture of S. mutans P42S grown overnight was transferred (2%) to fresh BHI medium and grown until an OD₆₀₀ of 0.7 was reached. Phage M102AD (10³ PFU) was added to 900 μl of this culture and allowed to adsorb for 15 min at 37°C. Cultures were then centrifuged for 1 min at 13,200 rpm, and the titer of the supernatant was determined to determine the fraction of the phages that did not adsorb to the host cells. A BIM was considered to have a reduced phage adsorption phenotype if <80% of the added phage particles had adsorbed to the BIM.