Structure of an acidic polysaccharide from the marine bacterium Pseudoalteromonas flavipulchra NCIMB 2033(T)

Natural extract and its fractions isolated from the marine bacterium Pseudoalteromonas flavipulchra STILL-33 have antioxidant and antiaging activities in Schizosaccharomyces pombe

Investigations into the potential for pharmacological inhibition of the aging process and the onset of age-related disease are increasingly garnering attention. Here, we analyzed the antiaging properties of natural compounds derived from several marine bacteria in vitro and in vivo using the fission yeast Schizosaccharomyces pombe. The Pseudoalteromonas flavipulchra STILL-33 extract exhibited high antioxidant and antiglycation activities in vitro. We then characterized two antioxidant active fractions isolated from this extract. In addition, we showed that the P. flavipulchra STILL-33 extract or either of its two active fractions (Fractions 1 and 2) could extend the longevity of fission yeast. Moreover, the particular extract and two active fractions were found to induce mitochondrial activity and to delay the G1 phase of the fission yeast cell cycle, perhaps by improving the aging process. The P. flavipulchra STILL-33 extract and Fraction 1 also increased the expression of the catalase-encoding ctt1+ gene and thereby decreased the reactive oxygen species level. Structural analysis showed that Fraction 1 was dominated by l-arginine and ipriflavone, and we showed indeed that the two corresponding commercial products increase the fission yeast lifespan. As for Fraction 2 was identified as the putative structure of butamben. Together, these results should facilitate the discovery of additional antiaging compounds from P. flavipulchra and ultimately the development of novel antiaging compounds for pharmaceutical use.

Genome Analysis and Characterisation of the Exopolysaccharide Produced by Bifidobacterium longum subsp. longum 35624™

The Bifibobacterium longum subsp. longum35624^™ strain (formerly named Bifidobacterium longum subsp. infantis) is a well described probiotic with clinical efficacy in Irritable Bowel Syndrome clinical trials and induces immunoregulatory effects in mice and in humans. This paper presents (a) the genome sequence of the organism allowing the assignment to its correct subspeciation longum; (b) a comparative genome assessment with other B. longum strains and (c) the molecular structure of the 35624 exopolysaccharide (EPS₆₂₄). Comparative genome analysis of the 35624 strain with other B. longum strains determined that the sub-speciation of the strain is longum and revealed the presence of a 35624-specific gene cluster, predicted to encode the biosynthetic machinery for EPS₆₂₄. Following isolation and acid treatment of the EPS, its chemical structure was determined using gas and liquid chromatography for sugar constituent and linkage analysis, electrospray and matrix assisted laser desorption ionization mass spectrometry for sequencing and NMR. The EPS consists of a branched hexasaccharide repeating unit containing two galactose and two glucose moieties, galacturonic acid and the unusual sugar 6-deoxy-L-talose. These data demonstrate that the B. longum35624 strain has specific genetic features, one of which leads to the generation of a characteristic exopolysaccharide.

Structural Investigation of the Oligosaccharide Portion Isolated from the Lipooligosaccharide of the Permafrost Psychrophile Psychrobacter arcticus 273-4

Psychrophilic microorganisms have successfully colonized all permanently cold environments from the deep sea to mountain and polar regions. The ability of an organism to survive and grow in cryoenviroments depends on a number of adaptive strategies aimed at maintaining vital cellular functions at subzero temperatures, which include the structural modifications of the membrane. To understand the role of the membrane in the adaptation, it is necessary to characterize the cell-wall components, such as the lipopolysaccharides, that represent the major constituent of the outer membrane. The aim of this study was to investigate the structure of the carbohydrate backbone of the lipooligosaccharide (LOS) isolated from the cold-adapted Psychrobacter arcticus 273-4. The strain, isolated from a 20,000-to-30,000-year-old continuously frozen permafrost in Siberia, was cultivated at 4 °C. The LOS was isolated from dry cells and analyzed by means of chemical methods. In particular, it was degraded either by mild acid hydrolysis or by hydrazinolysis and investigated in detail by ¹H and ¹³C NMR spectroscopy and by ESI FT-ICR mass spectrometry. The oligosaccharide was characterized by the substitution of the heptose residue, usually linked to Kdo in the inner core, with a glucose, and for the unusual presence of N-acetylmuramic acid.

O-antigens of bacteria of the genus providencia: structure, serology, genetics, and biosynthesis

The genus Providencia consists of eight species of opportunistic pathogenic enterobacteria that can cause enteric diseases and urinary tract infections. The existing combined serological classification scheme of three species, P. alcalifaciens, P. stuartii, and P. rustigianii, is based on the specificity of O-antigens (O-polysaccharides) and comprises 63 O-serogroups. Differences between serogroups are related to polymorphism at a specific genome locus, the O-antigen gene cluster, responsible for O-antigen biosynthesis. This review presents data on structures of 36 O-antigens of Providencia, many of which contain unusual monosaccharides and non-carbohydrate components. The structural data correlate with the immunospecificity of the O-antigens and enable substantiation on a molecular level of serological relationships within the genus Providencia and between strains of Providencia and bacteria of the genera Proteus, Escherichia, and Salmonella. Peculiar features of the O-antigen gene cluster organization in 10 Providencia serogroups and biosynthetic pathways of nucleotide precursors of specific monosaccharide components of the O-antigens also are discussed.

The structural diversity of carbohydrate antigens of selected gram-negative marine bacteria

Marine microorganisms have evolved for millions of years to survive in the environments characterized by one or more extreme physical or chemical parameters, e.g., high pressure, low temperature or high salinity. Marine bacteria have the ability to produce a range of biologically active molecules, such as antibiotics, toxins and antitoxins, antitumor and antimicrobial agents, and as a result, they have been a topic of research interest for many years. Among these biologically active molecules, the carbohydrate antigens, lipopolysaccharides (LPSs, O-antigens) found in cell walls of gram-negative marine bacteria, show great potential as candidates in the development of drugs to prevent septic shock due to their low virulence. The structural diversity of LPSs is thought to be a reflection of the ability for these bacteria to adapt to an array of habitats, protecting the cell from being compromised by exposure to harsh environmental stress factors. Over the last few years, the variety of structures of core oligosaccharides and O-specific polysaccharides from LPSs of marine microrganisms has been discovered. In this review, we discuss the most recently encountered structures that have been identified from bacteria belonging to the genera Aeromonas, Alteromonas, Idiomarina, Microbulbifer, Pseudoalteromonas, Plesiomonas and Shewanella of the Gammaproteobacteria phylum; Sulfitobacter and Loktanella of the Alphaproteobactera phylum and to the genera Arenibacter, Cellulophaga, Chryseobacterium, Flavobacterium, Flexibacter of the Cytophaga-Flavobacterium-Bacteroides phylum. Particular attention is paid to the particular chemical features of the LPSs, such as the monosaccharide type, non-sugar substituents and phosphate groups, together with some of the typifying traits of LPSs obtained from marine bacteria. A possible correlation is then made between such features and the environmental adaptations undertaken by marine bacteria.

Structural characterization and ecological roles of a novel exopolysaccharide from the deep-sea psychrotolerant bacterium Pseudoalteromonas sp. SM9913

Pseudoalteromonas sp. SM9913 is a psychrotolerant bacterium isolated from deep-sea sediment. The structural characterization and ecological roles of the exopolysaccharide (EPS) secreted by this strain were studied in this work. The yield of the EPS increased as the culture temperature decreased in the range 30-10 degrees C, and it reached 5.25 g l(-1) (dry weight) under optimal growth conditions (15 degrees C, 52 h). EPS fraction was purified and its structure was identified by the combination of NMR spectra, high-resolution mass spectrometry (HRMS) analysis and methylation analysis. The ratio of the sugar units, the acetyl group and the ethoxyl group was close to 4 : 5 : 1. The major sugar unit of the EPS was 6-linked glucose (61.8 %); other sugar units present included terminal arabinofuranosyl (11.0 %) and glucopyranosyl (11.2 %) residues and a small amount of other sugar derivatives. Its structure was different from EPSs reported for other marine bacteria. Besides the structural elucidation of the EPS, its ecological roles were studied. This EPS could enhance the stability of the cold-adapted protease MCP-01 secreted by the same strain through preventing its autolysis. It could bind many metal ions, including Fe(2+), Zn(2+), Cu(2+), Co(2+). It was also a very good flocculating agent and could conglomerate colloidal and suspended particles. These results indicated that the EPS secreted by strain SM9913 might help this strain enrich the proteinaceous particles and the trace metals in the deep-sea environment, stabilize the secreted cold-adapted proteases and avoid its diffusion. This is believed to be the first report on the structure of the EPS secreted by a deep-sea psychrotolerant bacterium and its ecological roles. According to these results and other studies, a schematic diagram of the lifestyle of the deep-sea psychrotolerant strain SM9913 is suggested.

The structure of the O-polysaccharide from the lipopolysaccharide of Providencia alcalifaciens O36 containing 3-deoxy-d-manno-oct-2-ulosonic acid

An oligosaccharide that corresponds to the repeating unit of the O-polysaccharide was obtained by mild acid degradation of the lipopolysaccharide of Providencia alcalifaciens O36. Structural studies of the oligosaccharide and O-deacylated lipopolysaccharide were performed using sugar and methylation analyses along with (1)H and (13)C NMR spectroscopy, including 2D (1)H,(1)H COSY, TOCSY, ROESY, and H-detected (1)H,(13)C HSQC and HMBC experiments. It was found that the O-polysaccharide is built up of linear trisaccharide repeating units containing 2-acetamido-2-deoxyglucose, 6-deoxy-l-talose (l-6dTal), and 3-deoxy-d-manno-oct-2-ulosonic acid (Kdo) and has the following structure. [structure: see text]

Structures of polysaccharides and oligosaccharides of some Gram-negative marine Proteobacteria

The chemical structures of polysaccharides and LPS core oligosaccharides, isolated from various Gram-negative marine bacteria from the genera Pseudoalteromonas and Shewanella belonging to the Alteromonadaceae family and gamma-subclass of Proteobacteria, are reviewed. The polysaccharides are distinguished by the acidic character (e.g., due to the presence of hexuronic and aldulosonic acids and their derivatives) and the occurrence of unusual sugars, including N-acyl derivatives of 6-deoxyamino sugars, such as N-acetyl-D-quinovosamine, N-acetyl-L-fucosamine and N-acetyl-6-deoxy-L-talosamine, and higher sugars like 2,6-dideoxy-2-acetamido-4-C-(3'-carboxamide-2',2'-dihydroxypropyl)-D-galactopyranose (shewanellose). Many constituent sugars have various uncommon non-sugar substituents, such as alanine, formic, lactic and hydroxybutyric acids, sulfate, phosphate, and 2-aminopropane-1,3-diol.