To further investigate the mechanis

To further investigate the mechanisms of QQ activity, the supernatant of Le1-2 and Lw1-1 (two of the most active isolates) with extracellular QQ activity) was fractionated by size exclusion chromatography (SEC).

To this end gravity flow columns with a cut-off value of 6000 Da (Econo-Pac 10DG) were used according to the minimal dilution protocol instructions supplied by themanufacturer (Bio-Rad Laboratories SA/NV, Eke, Belgium). In brief, 3 ml of sterile supernatant was poured onto the column and a first fraction, containing the higher molecular weight
components (N6000 Da), was eluted with 4 ml MilliQ water.

Subsequently,smallermolecularweight componentswere elutedwith 8 ml of
MilliQwater, yielding 4 subsequent fractions of 2 ml each. The fractions obtained were then again tested for QQ activity in the same way as described above.