title: In vitro fermentation of lactulose by human gut bacteria.
abstract: Lactulose has been known as a prebiotic that can selectively stimulate the growth of beneficial bifidobacteria and lactobacilli. Recent studies have indicated that Streptococcus mutans, Clostridium perfringens, and Faecalibacterium prausnitzii are also able to utilize lactulose. However, the previous studies mainly focused on the utilization of lactulose by individual strains, and few studies were designed to identify the species that could utilize lactulose among gut microbiota. This study aimed to identify lactulose-metabolizing bacteria in the human gut, using in silico and traditional culture methods. The prediction results suggested that genes for the transporters and glycosidases of lactulose are well distributed in the genomes of 222 of 453 strains of gastrointestinal-tract bacteria. The screening assays identified 35 species with the ability to utilize lactulose, of which Cronobacter sakazakii, Enterococcus faecium, Klebsiella pneumoniae, and Pseudomonas putida were reported for the first time to be capable of utilizing lactulose. In addition, significant correlations between lactulose and galactooligosaccharide metabolism were found. Thus, more attention should be paid to bacteria besides bifidobacteria and lactobacilli to further investigate the relationship between functional oligosaccharides and gut bacteria.
authors.affiliation: State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University , Wuxi 214122, People's Republic of China.
authors.forename: Bingyong
authors.initials: B
authors.lastname: Mao
authors.forename: Dongyao
authors.initials: D
authors.lastname: Li
authors.forename: Jianxin
authors.initials: J
authors.lastname: Zhao
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Liu
authors.forename: Zhennan
authors.initials: Z
authors.lastname: Gu
authors.forename: Yong Q
authors.initials: YQ
authors.lastname: Chen
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
mesh_terms: D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D005243:Feces / Q000382:microbiology; D005285:Fermentation; D041981:Gastrointestinal Tract / Q000382:microbiology*; D006801:Humans; D007792:Lactulose / Q000378:metabolism*; D008969:Molecular Sequence Data; D010802:Phylogeny
chemical_list: D007792:Lactulose
keywords: intestine; lactulose; microbiota; oligosaccharides; utilization