Coaggregation of S. mutans wild type (WT) and ΔrpoE mutant with oral microorganisms without (A)/with (B) Proteinase K treatment.

aThe settlement of flocs is record after 90 minutes as shown in the first column, the number of ‘+’ indicates the strength of floc settlement, while ‘−’ indicates no visible coaggregation flocs, and ‘nd’ means not determined. The optical density (OD600) of the supernatant is also recorded as shown in the second column. Since each strain had a similar optical density before mixing, the turbidity changes helped to judge coaggregation strength.