Structural characterisation of two medium molecular mass exopolysaccharides produced by the bacterium Lactobacillus fermentum Lf2.

Under optimized conditions, the lactic acid bacterium Lactobacillus fermentum Lf2 secretes up to 2 gL of a mixture of polysaccharides into the fermentation medium when grown on sucrose. Earlier studies had shown that the mixture is biologically active and work was undertaken to characterise the polysaccharides. Preparative size exclusion chromatography was used to separate a high molecular mass β-glucan (weight average mass of 1.

Isolation and characterization of a novel exopolysaccharide secreted by Lactobacillus mucosae VG1.

A novel strain of Lactobacillus mucosae was isolated from a faecal sample of an individual who had adhered to a strict vegetarian diet for nine years. The strain displayed a ropy character when grown on plates and generated a relatively small amount (62 mg/L) of an exopolysaccharide (EPS) when grown in broth culture. The EPS eluted from a size exclusion chromatography column as a single band with a weight average molecular mass of 1.

Isolation and characterization of a high molecular mass β-glucan from Lactobacillus fermentum Lf2 and evaluation of its immunomodulatory activity.

When grown in a semi-defined medium, L. fermentum Lf2 synthesizes significant quantities (∼2 g/L) of two exopolysaccharides (EPS). The two EPS were separated by preparative size exclusion chromatography to give a high molecular mass β-glucan (1.

Genomic Insights Into A Novel, Alkalitolerant Nitrogen Fixing Bacteria, Strain ZS02.

Alkaline environments represent a significant challenge to the growth of micro-organisms. Despite this, there are a number of alkaline environments which contain active microbial communities. Here we describe the genome of a diazotrophic, alkalitolerant strain of which was isolated from a microcosm seeded with hyperalkaline soils resulting from lime depositions.

Developing cellulosic waste products as platform chemicals: protecting group chemistry of α-glucoisosaccharinic acid.

Alpha and beta-glucoisosaccharinic acids ((2S,4S)-2,4,5-trihydroxy-2-(hydroxymethyl)pentanoic acid and (2R,4S)-2,4,5-trihydroxy-2-(hydroxymethyl)pentanoic acid) which are produced when cellulosic materials are treated with aqueous alkali are potentially valuable platform chemicals. Their highly functionalised carbon skeleton, with fixed chirality at C-2 and C-4, makes them ideal starting materials for use in synthesis. In order to assess the potential of these saccharinic acids as platform chemicals we have explored the protecting group chemistry of the lactone form of alpha-glucoisosaccharinic acid (α-GISAL).

A Novel Rhamnose-Rich Hetero-exopolysaccharide Isolated from Lactobacillus paracasei DG Activates THP-1 Human Monocytic Cells.

Unlabelled: Lactobacillus paracasei DG is a bacterial strain with recognized probiotic properties and is used in commercial probiotic products. However, the mechanisms underlying its probiotic properties are mainly unknown. In this study, we tested the hypothesis that the ability of strain DG to interact with the host is at least partly associated with its ability to synthesize a surface-associated exopolysaccharide (EPS).

Microbial Community Evolution Is Significantly Impacted by the Use of Calcium Isosaccharinic Acid as an Analogue for the Products of Alkaline Cellulose Degradation.

Diasteriomeric isosaccharinic acid (ISA) is an important consideration within safety assessments for the disposal of the United Kingdoms' nuclear waste legacy, where it may potentially influence radionuclide migration. Since the intrusion of micro-organisms may occur within a disposal concept, the impact of ISA may be impacted by microbial metabolism. Within the present study we have established two polymicrobial consortia derived from a hyperalkaline soil.

Phosphorothioate anti-sense oligonucleotides: the kinetics and mechanism of the sulfurisation of phosphites by phenylacetyl disulfide (PADS).

In the pharmaceutical industry the sulfurisation of nucleotide-phosphites to produce more biologically stable thiophosphates is often achieved using 'aged' solutions of phenylacetyl disulfide (PADS) which consist of a mixture of polysulfides that are more efficient sulfur transfer reagents. However, both 'fresh' and 'aged' solutions of PADS are capable of the sulfurisation of phosphites. The rates of both processes in acetonitrile are first order in sulfurising agent, phosphite and a pyridine base, although with 'aged' PADS the rate becomes independent of base at high concentrations.

Phosphorothioate anti-sense oligonucleotides: the kinetics and mechanism of the generation of the sulfurising agent from phenylacetyl disulfide (PADS).

The synthesis of phosphorothioate oligonucleotides is often accomplished in the pharmaceutical industry by the sulfurisation of the nucleotide-phosphite using phenylacetyl disulfide (PADS) which has an optimal combination of properties. This is best achieved by an initial 'ageing' of PADS for 48 h in acetonitrile with 3-picoline to generate polysulfides. The initial base-catalysed degradation of PADS occurs by an E1cB-type elimination to generate a ketene and acyldisulfide anion.

A study of the metal binding capacity of saccharinic acids formed during the alkali catalysed decomposition of cellulosic materials: nickel complexation by glucoisosaccharinic acids and xyloisosaccharinic acids.

The stoichiometry of the metal complexes formed between nickel and the ligand β-glucoisosaccharinic acid (β-GISA) and a racemic mixture of enantiomers of xyloisosaccharinic acid (XISA) has been determined at both neutral and alkaline pHs. Bjerrum plots, Job's plots and conductance measurements indicated that for each of the systems one to one Ni(ligand) complexes were formed at near neutral pHs (<7.5).

Isolation of sophorose during sophorolipid production and studies of its stability in aqueous alkali: epimerisation of sophorose to 2-O-β-D-glucopyranosyl-D-mannose.

NMR and anion exchange chromatography analysis of the waste streams generated during the commercial production of sophorolipids by the yeast Candida bombicola identified the presence of small but significant quantities (1% w/v) of free sophorose. Sophorose, a valuable disaccharide, was isolated from the aqueous wastes using a simple extraction procedure and was purified by chromatography on a carbon celite column providing easy access to large quantities of the disaccharide. Experiments were undertaken to identify the origin of sophorose and it is likely that acetylated sophorose derivatives were produced by an enzyme catalysed hydrolysis of the glucosyl-lipid bond of sophorolipids; the acetylated sophorose derivatives then undergo hydrolysis to release the parent disaccharide.

Pancreatic amylase is an environmental signal for regulation of biofilm formation and host interaction in Campylobacter jejuni.

Campylobacter jejuni is a commensal bacterium in the intestines of animals and birds and a major cause of food-borne gastroenteritis in humans worldwide. Here we show that exposure to pancreatic amylase leads to secretion of an α-dextran by C. jejuni and that a secreted protease, Cj0511, is required.

Anoxic Biodegradation of Isosaccharinic Acids at Alkaline pH by Natural Microbial Communities.

One design concept for the long-term management of the UK's intermediate level radioactive wastes (ILW) is disposal to a cementitious geological disposal facility (GDF). Under the alkaline (10.013.

Evidence of the generation of isosaccharinic acids and their subsequent degradation by local microbial consortia within hyper-alkaline contaminated soils, with relevance to intermediate level radioactive waste disposal.

The contamination of surface environments with hydroxide rich wastes leads to the formation of high pH (>11.0) soil profiles. One such site is a legacy lime works at Harpur Hill, Derbyshire where soil profile indicated in-situ pH values up to pH 12.

Biodegradation of the alkaline cellulose degradation products generated during radioactive waste disposal.

The anoxic, alkaline hydrolysis of cellulosic materials generates a range of cellulose degradation products (CDP) including α and β forms of isosaccharinic acid (ISA) and is expected to occur in radioactive waste disposal sites receiving intermediate level radioactive wastes. The generation of ISA's is of particular relevance to the disposal of these wastes since they are able to form complexes with radioelements such as Pu enhancing their migration. This study demonstrates that microbial communities present in near-surface anoxic sediments are able to degrade CDP including both forms of ISA via iron reduction, sulphate reduction and methanogenesis, without any prior exposure to these substrates.

The structure and immunomodulatory activity on intestinal epithelial cells of the EPSs isolated from Lactobacillus helveticus sp. Rosyjski and Lactobacillus acidophilus sp. 5e2.

The Lactic acid bacteria (LAB) Lactobacillus acidophilus sp. 5e2 and Lactobacillus helveticus sp. Rosyjski both secrete exopolysaccharides (EPSs) into their surrounding environments during growth.

Behaviour of xyloisosaccharinic acid and xyloisosaccharino-1,4-lactone in aqueous solutions at varying pHs.

Xyloisosaccharinic acid is one of the major degradation products formed during the alkali catalysed hydrolysis of hemicelluloses. In acidic solution xyloisosaccharinic acid undergoes an acid catalysed lactonisation to generate xyloisosaccharino-1,4-lactone. We report here the solution phase properties of xyloisosaccharinic including measurement of its aqueous pK(a) (3.

1,2,4-Dithiazole-5-ones and 5-thiones as efficient sulfurizing agents of phosphorus(III) compounds--a kinetic comparative study.

The sulfurization efficiency of 25 3-substituted-1,2,4-dithiazole-5-ones and 5-thiones towards triphenyl phosphite in acetonitrile, DCM, THF and toluene at 25 °C was evaluated. All the 1,2,4-dithiazoles are much better sulfurizing reagents than commercially available agents (PADS, TETD, Beaucage's reagent). The most efficient sulfurizing agents in all solvents are 3-phenoxy (4), 3-phenylthio (5) and 3-ethoxy-1,2,4-dithiazole-5-one (1) whose reactivity is at least two orders of magnitude higher than that of other 1,2,4-dithiazoles.

A robust method for the synthesis and isolation of β-gluco-isosaccharinic acid ((2R,4S)-2,4,5-trihydroxy-2-(hydroxymethyl)pentanoic acid) from cellulose and measurement of its aqueous pK(a).

In alkaline pulping wood pulp is reacted with concentrated aqueous alkali at elevated temperatures. In addition to producing cellulose for the manufacture of paper, alkaline pulping also generates large amounts of isosaccharinic acids as waste products. Isosaccharinic acids are potentially useful raw materials: they are good metal chelating agents and, in their enantiomerically pure form, they are valuable carbon skeletons with predefined stereochemistry that can be easily functionalised for use in synthesis.

Structure of the high molecular weight exopolysaccharide produced by Bifidobacterium animalis subsp. lactis IPLA-R1 and sequence analysis of its putative eps cluster.

The bile adapted strain Bifidobacterium animalis subsp. lactis IPLA-R1 secretes a high molecular weight exopolysaccharide (HMW-EPS) when grown on the surface of agar-MRSC. This EPS is composed of L-rhamnopyranosyl, D-glucopyranosyl, D-galactopyranosyl and D-galactofuranosyl residues in the ratio of 3:1:1:1.

The kinetics and mechanism of the acid-catalysed detritylation of nucleotides in non-aqueous solution.

The kinetics and mechanism of the deprotection (detritylation) of 5'-O-(4,4'-dimethoxytrityl)-2'-deoxythymidine nucleoside catalysed by dichloroacetic acid to give a 4,4'-dimethoxytrityl carbocation have been studied in toluene, dichloromethane and acetonitrile. There is little or no effect of solvent polarity on the equilibrium and rate constants. Entropies of activation are highly negative approximately -105 J K(-1) mol(-1) and similarly show little variation with solvent.

The mechanism of the phosphoramidite synthesis of polynucleotides.

The mechanism of the coupling step in polynucleotide synthesis using 5'-4,4'-dimethoxytritylthymidine-3'-beta-cyanoethyl-N,N-diisopropylphosphoramidite as the phosphitylating agent and catalysed by the salt of saccharin and N-methylimidazole in acetonitrile has been studied by (31)P NMR. Pre- and post-equilibria between the activator salt and released diisopropylamine have been examined by (1)H NMR and ITC, which show that the salt between saccharin and diisopropylamine will be present in acetonitrile. Activation of the phosphoramidite by the salt of saccharin and N-methylimidazole involves nucleophilic catalysis and the formation of a reactive saccharin adduct bonded through its carbonyl oxygen to phosphorus.

Metal-specific allosteric activation and deactivation of a diamine.

The reaction of a potentially tetradentate bis(pyridyl-thiazole) ligand with acetone is allosterically activated upon complexation with Cd(II) but deactivated by reaction with Cu(I), demonstrating metal-specific allosteric controlled reactivity.

Determination of the structure and molecular weights of the exopolysaccharide produced by Lactobacillus acidophilus 5e2 when grown on different carbon feeds.

Lactobacillus acidophilus 5e2 when grown on skimmed milk, skimmed milk supplemented with sodium formate and skimmed milk supplemented with glucose secretes a branched heteropolysaccharide having a weight average molecular weight less than 450 kDa. The exopolysaccharide has a heptasaccharide repeat unit and is composed of D-glucose, D-galactose and N-acetyl-D-glucosamine in the molar ratio 3:3:1. Using chemical techniques and 1D and 2D-NMR spectroscopy the polysaccharide has been shown to possess the following repeat unit structure:

Mechanism of the sulfurisation of phosphines and phosphites using 3-amino-1,2,4-dithiazole-5-thione (xanthane hydride).

Contrary to a previous report, the sulfurisation of phosphorus(III) derivatives by 3-amino-1,2,4-dithiazole-5-thione (xanthane hydride) does not yield carbon disulfide and cyanamide as the additional reaction products. The reaction of xanthane hydride with triphenyl phosphine or trimethyl phosphite yields triphenyl phosphine sulfide or trimethyl thiophosphate, respectively, and thiocarbamoyl isothiocyanate which has been trapped with nucleophiles. The reaction pathway involves initial nucleophilic attack of the phosphorus at sulfur next to the thiocarbonyl group of xanthane hydride followed by decomposition of the phosphonium intermediate formed to products.