One mL aliquots of cultures was taken after 48 h of fermentation as outlined previously and then centrifuged for 15 min, at 4 °C and 8000 rpm. The cells were washed twice using PBS buffer. The cell pellet was re-suspended in 1 mL of PBS pH 7.0 with: (i) bile extract (0.3% w/v), or (ii) α-amylase (100 U mL