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The infant intestinal microbiota is often colonized by two subspecies of Bifidobacterium longum: subsp. infantis (B. infantis) and subsp. longum (B. longum). Competitive growth of B. infantis in the neonate intestine has been linked to the utilization of human milk oligosaccharides (HMO). However, little is known how B. longum consumes HMO. In this study, infant-borne B. longum strains exhibited varying HMO growth phenotypes. While all strains efficiently utilized lacto-N-tetraose, certain strains additionally metabolized fucosylated HMO. B. longum SC596 grew vigorously on HMO, and glycoprofiling revealed a preference for consumption of fucosylated HMO. Transcriptomes of SC596 during early-stage growth on HMO were more similar to growth on fucosyllactose, transiting later to a pattern similar to growth on neutral HMO. B. longum SC596 contains a novel gene cluster devoted to the utilization of fucosylated HMO, including genes for import of fucosylated molecules, fucose metabolism and two α-fucosidases. This cluster showed a modular induction during early growth on HMO and fucosyllactose. This work clarifies the genomic and physiological variation of infant-borne B. longum to HMO consumption, which resembles B. infantis. The capability to preferentially consume fucosylated HMO suggests a competitive advantage for these unique B. longum strains in the breast-fed infant gut.

婴儿肠道微生物群通常由双歧杆菌的两个亚种定植

婴儿亚种（B. infantis）和长双歧杆菌亚种（B. longum）。双歧杆菌在新生儿肠道中的竞争性生长与利用人乳寡糖（HMO）有关。然而，对于长双歧杆菌如何消耗 HMO 知之甚少。在这项研究中，婴儿携带的长双歧杆菌菌株表现出不同的 HMO 生长表型。虽然所有菌株都能有效地利用乳-N-四糖，但某些菌株还能代谢岩藻糖基 HMO。B. longum SC596 在 HMO 上生长旺盛，糖组学分析表明其优先消耗岩藻糖基 HMO。SC596 在 HMO 早期生长时的转录组与在岩藻乳糖上的生长更为相似，后来过渡到与在中性 HMO 上生长相似的模式。B. longum SC596 含有一个专门用于利用岩藻糖基 HMO 的新基因簇，包括导入岩藻糖基分子、岩藻糖代谢和两个α-岩藻糖苷酶的基因。这个簇在 HMO 和岩藻乳糖早期生长过程中表现出模块化诱导。这项工作阐明了婴儿携带的长双歧杆菌对 HMO 消耗的基因组和生理变异性，类似于 B. infantis。优先消耗岩藻糖基 HMO 的能力表明这些独特的长双歧杆菌菌株在母乳喂养婴儿肠道中具有竞争优势。