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The gut microbiota harvests energy from indigestible plant polysaccharides, forming short-chain fatty acids (SCFAs) that are absorbed from the bowel. SCFAs provide energy—presumably after easily digested food components have been absorbed from the small intestine. Infant night waking is believed by many parents to be due to hunger. Our objective was to determine whether faecal SCFAs are associated with longer uninterrupted sleep in infants. Infants (n = 57) provided faecal samples for determining SCFAs (7 months of age), and questionnaire data for determining infant sleep (7 and 8 months). Linear regression determined associations between SCFAs—faecal acetate, propionate and butyrate—and sleep. For each 1% higher propionate at 7 months of age, the longest night sleep was 6 (95% CI: 1, 10) minutes longer at both 7 and 8 months. A higher proportion of total faecal SCFA as propionate was associated with longer uninterrupted infant sleep.

International audience; Pectin is abundant in modern day diets, as it comprises the middle lamellae and one-third of the dry carbohydrate weight of fruit and vegetable cell walls. Currently there is no specialized model organism for studying pectin fermentation in the human colon, as our collective understanding is informed by versatile glycan-degrading bacteria rather than by specialist pectin degraders. Here we show that the genome of Monoglobus pectinilyticus possesses a highly specialized glycobiome for pectin degradation, unique amongst Firmicutes known to be in the human gut. Its genome encodes a simple set of metabolic pathways relevant to pectin sugar utilization, and its predicted glycobiome comprises an unusual distribution of carbohydrate-active enzymes (CAZymes) with numerous extracellular methyl/acetyl esterases and pectate lyases. We predict the M. pectinilyticus degradative process is facilitated by cell-surface S-layer homology (SLH) domain-containing proteins, which proteomics analysis shows are differentially expressed in response to pectin. Some of these abundant cell surface proteins of M. pectinilyticus share unique modular organizations rarely observed in human gut bacteria, featuring pectin-specific CAZyme domains and the cell wall-anchoring SLH motifs. We observed M. pectinilyticus degrades various pectins, RG-I, and galactan to produce polysaccharide degradation products (PDPs) which are presumably shared with other inhabitants of the human gut microbiome (HGM). This strain occupies a new ecological niche for a primary degrader specialized in foraging a habitually consumed plant glycan, thereby enriching our understanding of the diverse community profile of the HGM.

Lactobacillus reuteri strain 100-23 together with a Lactobacillus-free mouse model, provides a system with which the molecular traits underpinning bacterial commensalism in vertebrates can be studied. A polysaccharide was extracted from sucrose-containing liquid cultures of strain 100-23. Chemical analysis showed that this exopolysaccharide was a levan (β-2, 6-linked fructan). Mutation of the fructosyl transferase (ftf) gene resulted in loss of exopolysaccharide production. The ftf mutant was able to colonise the murine gastrointestinal tract in the absence of competition, but colonisation was impaired in competition with the wild type. Biofilm formation by the mutant on the forestomach epithelial surface was not impaired and the matrix between cells was indistinguishable from that of the wild type in electron micrographs. Colonisation of the mouse gut by the wild-type strain led to increased proportions of regulatory T cells (Foxp3+) in the spleen, whereas colonisation by the ftf mutant did not. Survival of the mutant in sucrose-containing medium was markedly reduced relative to the wild type. Comparison of the genomic ftf loci of strain 100-23 with other L. reuteri strains suggested that the ftf gene was acquired by lateral gene transfer early in the evolution of the species and subsequently diversified at accelerated rates. Levan production by L. reuteri 100-23 may represent a function acquired by the bacterial species for life in moderate to high-sucrose extra-gastrointestinal environments that has subsequently been diverted to novel uses, including immunomodulation, that aid in colonisation of the murine gut.

Cell walls have been isolated from the mesocarp of mature grape (Vitis vinifera L.) berries. Tissue homogenates were suspended in 80% (v/v) ethanol to minimise the loss of water-soluble wall components and wet-sieved on nylon mesh to remove cytoplasmic material. The cell wall fragments retained on the sieve were subsequently treated with buffered phenol at pH 7.0, to inactivate any wall-bound enzymes and to dislodge small amounts of cytoplasmic proteins that adhered to the walls. Finally, the wall preparation was washed with chloroform/methanol (1:1, v/v) to remove lipids and dried by solvent exchange. Scanning electron microscopy showed that the wall preparation was essentially free of vascular tissue and adventitious protein of cytoplasmic origin. Compositional analysis showed that the walls consisted of approximately 90% by weight of polysaccharide and less than 10% protein. The protein component of the walls was shown to be rich in arginine and hydroxyproline residues. Cellulose and polygalacturonans were the major constituents, and each accounted for 30–40% by weight of the polysaccharide component of the walls. Substantial varietal differences were observed in the relative abundance of these two polysaccharides. Xyloglucans constituted approximately 10% of the polysaccharide fraction and the remainder was made up of smaller amounts of mannans, heteroxylans, arabinans and galactans.