2. Materials and methods
2.1. Enumeration and isolation of LAB
The study included 43 faecal samples of healthy infants up to 6
months of age: 31 breast-fed, 4 formula-fed and 8 mixed-fed
(breast and formula milk). The fresh faecal samples were
collected at home by the parents and were processed directly from
the nappies in the laboratory within 24 h of sample collection. For
isolation of LAB, ca. 1 g of freshly collected faeces were resuspended
in a saline solution (0.1% peptone and 0.85% NaCl), diluted, plated in
MRS agar (pH 5.7, Merck, Darmstadt, Germany) and incubated
under anaerobiosis at 37 C for 48e72 h. One representative colony
of each morphology (different in size, shape and/or colour from
other colonies) was individually picked and streaked on MRS agar
(Merck). Pure cultures were stored at 80 C in 20% (v/v) glycerol.