2. Materials and methods
2.1. Bacterial strains
B. longum subsp. infantis CCUG 52486 and B. infantis NCIMB
702205 were obtained from the culture collection of the University
of Göteborg in Sweden and the UK National Collection of Industrial,
Food and Marine Bacteria (NCIMB), respectively. Stock cultures
were maintained at −80 °C in trypticase phytone yeast extract
(TPY) medium containing 15% (v/v) glycerol. Frozen stocks were initially
propagated in Wilkins Chalgren anaerobe agar (WC) (Oxoid,
Hampshire, UK) under anaerobic conditions at 37 °C for 72 h. Two
successive growths of bacteria were carried out in 10 mL TPY broth
under anaerobic condition for 18 h. The bacterial cells were harvested
after the second growth cycle at 10,000×g for 15 min, at 4 °C. The
pellet was washed with sterile phosphate buffered saline (PBS)
(Oxoid, UK) and then resuspended in 10 mL of commercial pasteurised
skim milk to prepare the pre-culture