1 poster presented at the 24th International ICFMH Conference, Food Micro 2014, 1-4 Septembre, Nantes, FranceThe potential of phage K in the removal and prevention of Staphylococcus aureus biofilms on stainless
steel surfaces was examined. The host range of the phage was tested on 18 strains from the food
industry. Two out of six sensitive strains were selected for study of biofilms.
Immature 6-h-old biofilms were challenged wfth a wide range of multipticlties of infection {MOl,
0.01-500) for 18 h at 25ºc. A noticeable effect on cell number was appreciated at MOIs≥10, but no
effect was detected at lower MOis. Subsequently, 24 h-old biofilms (with a higher cell density and
a more dense extracellular matrix) were challenged too at MOIs between 0.01-3.0 for 24 hat 25ºc.
Again, a significant effect was only found at MOls > 1.
The effectiveness in the prevention of biofilm formation was examined by Infecting planktonlc
cultures of S. aureus with sub-lethal and lethal doses of phage K (MOIs 1-10-7-10.0). A notable effect
on cell number and biofilm biomass was observed from MOIs >1·10-5.
The potential of phage K as a tool for biohygienization in the food Industry acting specifically against
biofilms of S. aureus was thus shown. However, neither biofilm cells were completely removed nor
biofilm formation was totally prevented, and a sub-population of live cells was left In both cases As
a result, the effectiveness of two co-adjuvant-based strategies was subsequently assessed.
Combining DNase (0,1-10 mg/ml) with phage K (MOl of 0.3-3.0) did not show an additional effect on
the removal of 24 h-old-biofilms at 25°C. A 30 min pre-treatment at 37ºc aimed to enhance DNase
activity also had not effect. DNase did not show any effects by itself either. In contrast, combining
cis-2-decenoic acid {1 - 100 nM) with phage K (MOl of 0.03-0.3) seemed to show some effects on
biofilmsN
