Alterations in the Gut Microbiota and Metabolomics of Seafarers after a Six-Month Sea Voyage.

Maintaining the health of seafarers is a difficult task during long-term voyages. Little is known about the corresponding changes in the gut microbiome-host interaction. This study recruited 30 seafarers undertaking a 6-month voyage and analyzed their gut microbiota using 16S rRNA gene sequencing. Fecal untargeted metabolomics analysis was performed using liquid chromatography-mass spectrometry. Significant changes in the composition of the gut microbiota and an increased ratio of Firmicutes/Bacteroidetes at the end (day 180) of the 6-month voyage, relative to the start (day 0), were observed. At the genus level, the abundances of Holdemanella and Plesiomonas were significantly increased, while the abundance of Bacteroides was decreased. Predicted microbial functional analysis revealed significant decreases in folate biosynthesis and biotin metabolism. Furthermore, 20 differential metabolites within six differentially enriched human metabolic pathways (including arginine biosynthesis, lysine degradation, phenylalanine metabolism, sphingolipid metabolism, pentose and glucuronate interconversions, and glycine, serine, and threonine metabolism) were identified by comparing the fecal metabolites at day 0 and day 180. Spearman correlation analysis revealed close relationships between the 14 differential microbiota members and the six differential fecal metabolites that might affect specific human metabolic pathways. This study adopted a multi-omics approach and provides potential targets for maintaining the health of seafarers during long-term voyages. These findings are worthy of more in-depth exploration in future studies. IMPORTANCE Maintaining the health of seafarers undertaking long-term voyages is a difficult task. Apart from the alterations in the gut microbiome and fecal metabolites after a long-term voyage, our study also revealed that 20 differential metabolites within six differentially enriched human metabolic pathways are worthy of attention. Moreover, we found close relationships between the 14 differential microbiota members and the six differential fecal metabolites that might impact specific human metabolic pathways. Accordingly, preventative measures, such as adjusting the gut microbiota by decreasing potential pathobionts or increasing potential probiotics as well as offsetting the decrease in B vitamins and beneficial metabolites (e.g., d-glucuronic acid and citrulline) via dietary adjustment or nutritional supplements, might improve the health of seafarers during long-term sea voyages. These findings provide valuable clues about gut microbiome-host interactions and propose potential targets for maintaining the health of seafarers engaged in long-term sea voyages.

Chlorogenic acid-arabinose hybrid domains in coffee melanoidins: Evidences from a model system.

Arabinose from arabinogalactan side chains was hypothesized as a possible binding site for chlorogenic acids in coffee melanoidins. To investigate this hypothesis, a mixture of 5-O-caffeoylquinic acid (5-CQA), the most abundant chlorogenic acid in green coffee beans, and (α1 → 5)-L-arabinotriose, structurally related to arabinogalactan side chains, was submitted to dry thermal treatments. The compounds formed during thermal processing were identified by electrospray ionization mass spectrometry (ESI-MS) and characterized by tandem MS (ESI-MS(n)). Compounds composed by one or two CQAs covalently linked with pentose (Pent) residues (1-12) were identified, along with compounds bearing a sugar moiety but composed exclusively by the quinic or caffeic acid moiety of CQAs. The presence of isomers was demonstrated by liquid chromatography online coupled to ESI-MS and ESI-MS(n). Pent1-2CQA were identified in coffee samples. These results give evidence for a diversity of chlorogenic acid-arabinose hybrids formed during roasting, opening new perspectives for their identification in melanoidin structures.

Structural characterization and cytotoxic properties of an apiose-rich pectic polysaccharide obtained from the cell wall of the marine phanerogam Zostera marina.

Zosterin, an apiose-rich pectic polysaccharide, was extracted and purified from the sea grass Zostera marina. Structural studies conducted by gas chromatography and NMR spectroscopy on a purified zosterin fraction (AGU) revealed a typical apiogalacturonan structure comprising an alpha-1,4-d-galactopyranosyluronan backbone substituted by 1,2-linked apiofuranose oligosaccharides and single apiose residues. The average molecular mass of AGU was estimated to be about 4100 Da with a low polydispersity. AGU inhibited proliferation of A431 human epidermoid carcinoma cells with an approximate IC(50) value of 3 microg/mL (0.7 microM). In addition, AGU inhibited A431 cell migration and invasion. Preliminary experiments showed that inhibition of metalloproteases expression could play a role in these antimigration and anti-invasive properties. Autohydrolysis of AGU, which eliminated apiose and oligo-apiose substituents, led to a virtual disappearance of cytotoxic properties, thus suggesting a direct structure-function relationship with the apiose-rich hairy region of AGU.

Structure and bioactivity of the polysaccharides in medicinal plant Dendrobium huoshanense.

Detailed structures of the active polysaccharides extracted from the leaf and stem cell walls and mucilage of Dendrobium huoshanense are determined by using various techniques, including chromatographic, spectroscopic, chemical, and enzymatic methods. The mucilage polysaccharide exhibits specific functions in activating murine splenocytes to produce several cytokines including IFN-gamma, IL-10, IL-6, and IL-1alpha, as well as hematopoietic growth factors GM-CSF and G-CSF. However, the deacetylated mucilage obtained from an alkaline treatment fails to induce cytokine production. The structure and bioactivity of mucilage components are validated by further fractionation. This is the first study that provides clear evidence for the structure and activity relationship of the polysaccharide in D. huoshanense.

[Production of polysaccharides by callus cultures of common duckweed].

Callus lines of common duckweed produced acid arabinogalactan and pectin in an amount varying from 1 to 3% of dry weight. The arabinogalactan specimens from the cell lines studied displayed a similar monosaccharide composition. The duckweed callus lines whose arabinogalactans contained apiose residues (1-2%) were found. All pectin specimens had a similar qualitative monosaccharide composition but differed in the quantitative content of monosaccharide residues. The lines with high contents of galactose, arabinose, and apiose in pectin specimens were obtained. The total content of neutral monosaccharide residues in pectins varied from 26 to 50%.

Direct stereochemical assignment of hexose and pentose residues in flavonoid O-glycosides by fast atom bombardment and electrospray ionization mass spectrometry.

Mass spectrometric methods have been developed which allow the direct stereochemical assignment of terminal monosaccharide residues in flavonoid O-glycosides without the need for chemical hydrolysis. Standards containing a glucose, galactose, mannose, xylose, arabinose or apiose residue were examined because these monosaccharides are by far the most commonly encountered in flavonoid glycosides. Following acetylation, the major peracetylated sugar related fragments, generated by fast atom bombardment (FAB) or electrospray ionization (ESI), were selected for collisional activation employing a broad range of collision energies. Both FAB and ESI proved to be useful as ionization techniques. Stereoselective fragmentation was achieved and allowed us clearly to differentiate and characterize isomeric monosaccharide residues. The method developed was successfully applied to an unknown flavonoid containing a terminal pentose and hexose residue which was isolated from Farsetia aegyptia.

[Composition, physico-chemical properties and molecular superstructure of dietary fiber preparations of the cellan type]. / Zusammensetzung, physiko-chemische Eigenschaften und molekulare Uberstruktur von Ballaststoffpräparaten vom Cellan-Typ.

Dietary fiber preparations of "cellan" type were prepared from apples, white cabbage, sugar beet pulp, soy hulls and wheat bran by treatment with amylolytic and proteolytic enzymes as well as by chemical extractions. Scanning electron microscopic examinations show different morphological structures of the preparations and a high maintenance of native biomolecular superstructure. The content of pectin, protein, polysaccharide-hexoses and -pentoses and the composition of monosaccharides (also after their treatment with 4 or 8% sodium hydroxide) were determined. The cellans possess waterbinding capacities (WBC) between < 10 and > 25 g H2O/g and waterholding capacities between < 10 and > 50 g H2O/g. The WBC is related to the internal surface; it diminishes after treatment with NaOH. The interactions between the cellans and the adsorbed water were characterized by NMR-spin-lattice relaxation time T1. The molecular mobility increases as the water content grows. The T1-values of dried cellans decreased with increasing degree of moisture before drying. The supermolecular structure is comparatively disordered. Only in case of soy cellan a crystalline cellulose-I-modification could be identified by X-ray-diffraction pattern, esp. after NaOH treatment. The low degree of order of cellans was observed in the 13C-NMR spectra, too. Only the soy hull preparation resulted in a spectrum corresponding to well-ordered cellulose. The botanic source has an essential influence on the physico-chemical properties of dietary fiber preparations of cellan type.

Preparation and chemical composition of the cell walls of Streptococcus mutans.

Purified cell walls from Streptococcus mutans strain BHT were prepared without the use of proteolytic enzymes in order to retain all cell wall constituents for chemical analysis. Of four methods employed, the Ribi cell fractionator produced disrupted cell suspensions which could be most thoroughly purified on sucrose gradients. Results of chemical analyses on purified cell walls prepared in this 8.9% glycerol teichoic acid, 33.6% non-peptidoglycan polysaccharide, and 49.9% peptidoglycan.

Immunological and chemical studies of the streptococcal group O protein type antigens.

Two antigens present in group O streptococci have been described and are designated as type antigens. No other antigens are present in extracts of group O cells in significant quantity. Antigen I is a cell wall protein, and II is a nucleoprotein of undetermined cell location. The immunological specificity of the latter resides only in the protein. Both antigens have been extracted from the cell with water or 0.2 n HCl (pH 2) at 100 C, and antigen I can be removed by trypsin. After purification, pH 2 was found to destroy the serological activity of each antigen. Antgens I and II and also the O polysaccharide antigen can be distinguished on a single agar-gel diffusion plate with group O whole-cell antiserum. N- and C-terminal amino acid analyses and total amino acid composition prove that I and II are separate molecular species. Each possesses properties which separate them from the streptococcal M, R, and T proteins. Antigen I separated into three fractions, each possessing serological specificity, on a diethylaminoethyl-Sephadex column at pH 8.6 during an increase in buffer molarity. The protein is considered to possess a multiple unit structure. The results indicate that the O streptococci are limited to two serological types. Group O whole-cell antisera, after adsorption with a strain not containing the O polysaccharide, can now be prepared for the positive identification of the types of group O streptococci.