Department of Food Nutrition, Chungnam National University, Yuseong-gu, Daejeon, Korea.
PLoS One. 2013;8(2):e57535. doi: 10.1371/journal.pone.0057535. Epub 2013 Feb 26.
Bifidobacterium longum subsp. infantis is a common member of the intestinal microbiota in breast-fed infants and capable of metabolizing human milk oligosaccharides (HMO). To investigate the bacterial response to different prebiotics, we analyzed both cell wall associated and whole cell proteins in B. infantis. Proteins were identified by LC-MS/MS followed by comparative proteomics to deduce the protein localization within the cell. Enzymes involved in the metabolism of lactose, glucose, galactooligosaccharides, fructooligosaccharides and HMO were constitutively expressed exhibiting less than two-fold change regardless of the sugar used. In contrast, enzymes in N-Acetylglucosamine and sucrose catabolism were induced by HMO and fructans, respectively. Galactose-metabolizing enzymes phosphoglucomutase, UDP-glucose 4-epimerase and UTP glucose-1-P uridylytransferase were expressed constitutively, while galactokinase and galactose-1-phosphate uridylyltransferase, increased their expression three fold when HMO and lactose were used as substrates for cell growth. Cell wall-associated proteomics also revealed ATP-dependent sugar transport systems associated with consumption of different prebiotics. In addition, the expression of 16 glycosyl hydrolases revealed the complete metabolic route for each substrate. Mucin, which possesses O-glycans that are structurally similar to HMO did not induced the expression of transport proteins, hydrolysis or sugar metabolic pathway indicating B. infantis do not utilize these glycoconjugates.
长双歧杆菌亚种。婴儿是母乳喂养婴儿肠道微生物群的常见成员，能够代谢人乳寡糖（HMO）。为了研究细菌对不同益生元的反应，我们分析了双歧杆菌的细胞壁相关蛋白和全细胞蛋白。通过 LC-MS/MS 鉴定蛋白质，然后进行比较蛋白质组学，以推断细胞内蛋白质的定位。参与乳糖、葡萄糖、半乳糖寡糖、果寡糖和 HMO 代谢的酶持续表达，无论使用哪种糖，变化都不到两倍。相比之下，N-乙酰葡萄糖胺和蔗糖分解代谢中的酶分别被 HMO 和果聚糖诱导。半乳糖代谢酶磷酸葡糖变位酶、UDP-葡萄糖 4-差向异构酶和 UTP 葡萄糖-1-P 尿苷酰转移酶持续表达，而当 HMO 和乳糖用作细胞生长的底物时，半乳糖激酶和半乳糖-1-磷酸尿苷酰转移酶的表达增加了三倍。细胞壁相关蛋白质组学还揭示了与不同益生元消耗相关的 ATP 依赖性糖转运系统。此外，16 种糖苷水解酶的表达揭示了每种底物的完整代谢途径。黏蛋白具有与 HMO 结构相似的 O-聚糖，但没有诱导转运蛋白、水解或糖代谢途径的表达，表明双歧杆菌不利用这些糖缀合物。
