Fucosyllactoses (2'- or 3'-FL) account for up to 20% of human milk oligosaccharides (HMOs). Infant bifidobacteria, such as subsp. , utilize the lactose moiety to form lactate and acetate, and metabolize L-fucose to 1,2-propanediol (1,2-PD). is a common member of the adult gut microbiota that can produce butyrate from lactate and acetate, and convert 1,2-PD to propionate. Recently, a Swiss cohort study identified as one of the first butyrate producers in the infant gut. However, the global prevalence of and its role in utilization of HMO degradation intermediates remains unexplored. Fecal 16S rRNA gene libraries ( = 857) of humans of all age groups from Venezuela, Malawi, Switzerland, and the USA were screened for the occurrence of . Single and co-culture experiments of subsp. and were conducted in modified YCFA containing acetate and glucose, L-fucose, or FL. spp. ( = 56) of different origin were screened for the ability to metabolize L-fucose. Relative abundance of was low (10-10%) during the first months but increased and reached adult levels (0.01-10%) at 5-10 years of age in all four populations. In single culture, subsp. grew in the presence of all three carbohydrates while was metabolically active only with glucose. In co-culture also grew with L-fucose or FL. In co-cultures grown with glucose, acetate, and glucose were consumed and nearly equimolar proportions of formate and butyrate were formed. subsp. used L-fucose and produced 1,2-PD, acetate and formate in a ratio of 1:1:1, while 1,2-PD was used by to form propionate. consumed acetate, lactate and 1,2-PD released by subsp. from FL, and produced butyrate, propionate, and formate. Beside subsp. , and a strain of subsp. were able to utilize L-fucose. This study identified a trophic interaction of infant and during L-fucose degradation, and pointed at as a metabolically versatile species that occurs in infants and utilizes intermediates of bifidobacterial HMO fermentation.