Hydrophobicity was determined following the method proposed by Kimoto-Nira et al. (2010) with some modifications After 48 h of incubation the bacteria grown on the different
substrates (glucose, lactulose, GOS-La and GOS-Lu) were washed and suspended in PBS in order to obtain an OD620 of 1.0. One millilitre of n-hexadecane was added to 1.0 mL of cell suspensions.