Project description:Bifidobacteria dominate the composition of the neonatal gut microbiota in the first number of weeks following birth. A number of species in particular are found with a significantly higher frequency in the microbiome of breastfed infants, owing to their ability to rely on Human Milk Oligosacchraides (HMOs) as their sole carbohydrate substrate; namely B. bifidum, B. longum spp. infantis and B. breve. Bifidobacterium kashiwanohense is a species that has been isolated previously only from the faeces of infants, but extremely infrequently at that. Relatively little is currently known about the species itself, let alone the metabolic pathways that allow it to successfully establish a population in the infant gut. We have isolated a novel strain of B. kashiwanohense from the faeces of a breastfed infant on the basis of its ability to utilise the HMO component fucosyllactose as its sole carbohydrate source. In this study, we read and annotate the full genome sequence of this novel strain, and use the data obtained to direct our further experimental analysis of fucosyllactose metabolism in B. kashiwanohense. Using transcriptomic and growth analysis results, we identify the genes responsible for B. kashiwanohense to utilise fucosyllactose, and employ a combination of cloning, in vitro hydrolysis assays, and further, recombinant transcriptomic and growth assays to elucidate the pathway for fucosyllactose metabolism in B. kashiwanohense, as well as revealing insight into fucosyllactose and fucose metabolism in Bifidobacteria as whole.
Project description:The aim of this RNA-sequencing study is to measure differential gene expression in 8 intestinal bacteria (Bacteroides xylanisolvens, Bacteroides thetaiotaomicron, Bacteroides uniformis, Bifidobacterium adolescentis, Bifidobacterium catenulatum, Subdoligranulum variabile and Roseburia intestinalis, Agathobacter rectalis). The data highlight the coordinated action of genes within the same locus involved in the degradation of complex carbohydrates. These loci are well characterized in Bacteroidota species and referred to as polysaccharide utilization loci. In Bacillota and Actinomycetota species, these loci are not so clear-cut, athough the GP-PUL concept has already been proposed. Here we compare the differential gene expression in minimal culture medium supplemented with a complex carbohydrate with a minimal culture medium supplemented with glucose. This differential analysis reveals a source-specific genetic response and a coordinated expression of genes involved in carbohydrate transport, carbohydrate degradation and transcriptional activation of these complex enzymatic machineries.
