Purity was verified by spread plating samples onto blood and chocolate agar.
Similarly, a sample was plated onto solid beef heart infusion-turkey serum medium (BHI-TS, pH 7.4) (Ross and Karmon, 1970). All plating was performed in triplicate.
Quantification of inocula was performed via 10-fold serial dilutions in D-HS broth containing arginine and phenol red and measured as color changing units (CCU)/ml. For the M. flocculare inoculum (Table 1), a frozen stock of 1.5 ml was passed into 50 ml of modified Friis medium containing phenol red (Friis, 1975). This was incubated at 37 8C for 10 days resulting in a dark yellow color. Purity was checked as described above. The inoculum was used without further quantification by CCU (Table 1).