Isolation of bacterial strains
Serial dilutions of freshly collected pig faeces were made in quarter-strength Ringer’s solution, and 100 ml of each dilution was spread-plated onto MRS (Merck) and Rogosa (Merck) agar. Plates were incubated anaerobically at 378C for 48 h in a MK3 Anaerobic Workstation (dw Scientific, Shipley, West Yorkshire, UK). One to three colonies were random- ly selected from each of duplicate MRS and Rogosa plates of the highest dilution showing growth. Colonies were subcultured in MRS broth, and re- streaked onto MRS agar to ensure purity. Purified cultures were maintained at 2 808C in 20% (v / v) glycerol. Authentic reference strains and their origin are listed in Tables 1 and 2. They were cultured as described in the respective culture collection catalogues.