The protein composition of Bifidobacterium longum subsp. infantis (B. infantis) cultured for 2, 4, 6, and 8 hours in glucose, lactose, galactooligosaccharides, and 2'-fucosyllactose, respectively. Sample No. 41 represents the control; sample Nos. 6-9 represent B. infantis cultured for 2, 4, 6, and 8 hours in lactose, respectively; sample Nos. 16-19 represent B. infantis cultured for 2, 4, 6, and 8 hours in glucose, respectively; sample Nos. 26-29 represent B. infantis cultured for 2, 4, 6, and 8 hours in galactooligosaccharides, respectively; and sample Nos. 36-39 represent B. infantis cultured for 2, 4, 6, and 8 hours in 2'-fucosyllactose, respectively.