Figure 4.

Viability of Bifidobacteria after 24 h growth in porcine bile. B. breve UCC2003 WT, B. breve UCC2003 luxS, B. breve UCC2003 ${\text{EPS}}^{-}$, B. breve UCC2003 accC and B .breve UCC2003 Bbr_201 were grown in a microtiter plate in RCM supplemented with 0.5% (w/v) of porcine bile (biofilm formation conditions) and incubated for 24 h. Culture media was then diluted and spot plated on RCA to see if viable bacteria could be recovered and the CFU/ml was calculated (A). Experiments were carried out in triplicate and error bars represent standard deviation. Biofilm was also induced in testubes by growing the above strains in RCM supplemented with 0.5% (w/v) of porcine bile and incubated for 24 h (B). Supernant was removed and test tubes were washed twice to remove planktonic cells. Biofilm was then scraped off the test tubes, where formed, with a pipette tip and streaked out on RCA supplemeted with lactose and cysteine to obtain viable colony counts (top image). Test tubes were also stained with crystal violet to visualise biofilm (bottom image).