Tools in Oligosaccharide Synthesis. Elsevier; 2010. pp. 101-38. [DOI: 10.1016/s0065-2318(10)63004-1]

Stimulus-cleavable chemistry in the field of controlled drug delivery

This review comprehensively summarises stimulus-cleavable linkers from various research areas and their cleavage mechanisms, thus provides an insightful guideline to extend their potential applications to controlled drug release from nanomaterials.

Investigating the Product Profiles and Structural Relationships of New Levansucrases with Conventional and Non-Conventional Substrates

The synthesis of complex oligosaccharides is desired for their potential as prebiotics, and their role in the pharmaceutical and food industry. Levansucrase (LS, EC 2.4.1.10), a fructosyl-transferase, can catalyze the synthesis of these compounds. LS acquires a fructosyl residue from a donor molecule and performs a non-Lenoir transfer to an acceptor molecule, via β-(2→6)-glycosidic linkages. Genome mining was used to uncover new LS enzymes with increased transfructosylating activity and wider acceptor promiscuity, with an initial screening revealing five LS enzymes. The product profiles and activities of these enzymes were examined after their incubation with sucrose. Alternate acceptor molecules were also incubated with the enzymes to study their consumption. LSs from Gluconobacter oxydans and Novosphingobium aromaticivorans synthesized fructooligosaccharides (FOSs) with up to 13 units in length. Alignment of their amino acid sequences and substrate docking with homology models identified structural elements causing differences in their product spectra. Raffinose, over sucrose, was the preferred donor molecule for the LS from Vibrio natriegens, N. aromaticivorans, and Paraburkolderia graminis. The LSs examined were found to have wide acceptor promiscuity, utilizing monosaccharides, disaccharides, and two alcohols to a high degree.

Mechanisms of Action of Prebiotics and Their Effects on Gastro-Intestinal Disorders in Adults

In recent years, research has focused on the use of dietary fibers and prebiotics, since many of these polysaccharides can be metabolized by intestinal microbiota, leading to the production of short-chain fatty acids. The metabolites of prebiotic fermentation also show anti-inflammatory and immunomodulatory capabilities, suggesting an interesting role in the treatment of several pathological conditions. Galacto-oligosaccharide and short- and long-chain fructans (Fructo-oligosaccharides and inulin) are the most studied prebiotics, even if other dietary compounds seem to show the same features. There is an increasing interest in dietary strategies to modulate microbiota. The aim of this review is to explore the mechanisms of action of prebiotics and their effects on the principal gastro-intestinal disorders in adults, with a special focus on Galacto-oligosaccharides, Fructo-oligosaccharides, lactulose and new emerging substances which currently have evidence of prebiotics effects, such as xilooligosaccharides, soybean oligosaccharides, isomaltooligosaccharides, lactobionic acid, resistant starch and polyphenols.

Mechanisms of Action of Prebiotics and Their Effects on Gastro-Intestinal Disorders in Adults

In recent years, research has focused on the use of dietary fibers and prebiotics, since many of these polysaccharides can be metabolized by intestinal microbiota, leading to the production of short-chain fatty acids. The metabolites of prebiotic fermentation also show anti-inflammatory and immunomodulatory capabilities, suggesting an interesting role in the treatment of several pathological conditions. Galacto-oligosaccharide and short- and long-chain fructans (Fructo-oligosaccharides and inulin) are the most studied prebiotics, even if other dietary compounds seem to show the same features. There is an increasing interest in dietary strategies to modulate microbiota. The aim of this review is to explore the mechanisms of action of prebiotics and their effects on the principal gastro-intestinal disorders in adults, with a special focus on Galacto-oligosaccharides, Fructo-oligosaccharides, lactulose and new emerging substances which currently have evidence of prebiotics effects, such as xilooligosaccharides, soybean oligosaccharides, isomaltooligosaccharides, lactobionic acid, resistant starch and polyphenols.

Sensory analysis of juice blend containing isomalto-oligosaccharides produced by fermentation with Weissella cibaria

This study aimed at producing isomaltooligosaccharides in juice blends using orange juice and malt extract and assessing their acceptability. Different blend formulations were prepared and fermented, varying the concentration of orange juice, sucrose and malt extract. Dextransucrase from Weissella cibaria 10 M was used to enzymatically synthesize α(1-6) linked glucan-oligosaccharides by transglycosylation reactions, with maltose as acceptor carbohydrate and sucrose as donor. The optimal yield of oligosaccharides was after 24 h, producing 19.4 g/L of oligosaccharides (degree of polymerization 3) from 36 g/L maltose and 19 g/L sucrose. All the blend proved to be good alternatives for synthesizing isomalto-oligosaccharides with different degrees of polymerization. Sensory analysis showed good average acceptability compared to natural orange juice, achieving scores of around 6 on a 9-point hedonic scale. In a comprehensive analysis, juice blends containing orange juice and malt extract with Weissella cibaria to produce oligosaccharides exhibited good sensory indicators as an innovative prebiotic beverage. A prebiotic oligosaccharide beverage can be produced by enzymatic synthesis of oligosaccharides with different degrees of polymerization.

Extending the Scope of GTFR Glucosylation Reactions with Tosylated Substrates for Rare Sugars Synthesis

Functionalized rare sugars were synthesized with 2-, 3-, and 6-tosylated glucose derivatives as acceptor substrates by transglucosylation with sucrose and the glucansucrase GTFR from Streptococcus oralis. The 2- and 3-tosylated glucose derivatives yielded the corresponding 1,6-linked disaccharides (isomaltose analogues), whereas the 6-tosylated glucose derivatives resulted in 1,3-linked disaccharides (nigerose analogue) with high regioselectivity in up to 95 % yield. Docking studies provided insight into the binding mode of the acceptors and suggested two different orientations that were responsible for the change in regioselectivity.

Production, properties, and industrial food application of lactic acid bacteria-derived exopolysaccharides

Exopolysaccharides (EPS)-producing lactic acid bacteria (LAB) are industrially important microorganisms in the development of functional food products and are used as starter cultures or coadjutants to develop fermented foods. There is large variability in EPS production by LAB in terms of chemical composition, quantity, molecular size, charge, presence of side chains, and rigidity of the molecules. The main body of the review will cover practical aspects concerning the structural diversity structure of EPS, and their concrete application in food industries is reported in details. To strengthen the food application and process feasibility of LAB EPS at industrial level, a future academic research should be combined with industrial input to understand the technical shortfalls that EPS can address.

Metabolism of isomalto-oligosaccharides by Lactobacillus reuteri and bifidobacteria

Commercial isomalto-oligosaccharides (IMO) are functional food ingredients. They are composed of α(1→6)- and α(1→4)-linked oligosaccharides. IMO are partially indigestible, and dietary IMO stimulate beneficial members of intestinal microbiota, including lactobacilli and bifidobacteria. However, data on IMO metabolism by lactobacilli are not available. It was the aim of this study to identify metabolic pathways of IMO metabolism in lactobacilli. This study focused on the host-adapted species Lactobacillus reuteri. Metabolism of bifidobacteria was analysed for comparison. Commercial IMO contained IMO with a degree of polymerization (DP) of up to four and panose-series oligosaccharides (POS) with a DP of up to 5. Lactobacilli metabolized isomaltose preferentially over oligosaccharides with higher DP. Bifidobacteria preferentially metabolized oligosaccharides with higher DP and accumulated glucose. Metabolism of IMO and POS by L. reuteri was attributed to α(1→6)-specific glucanase DexB and maltose phosphorylase. Contribution of maltose phosphorylase was verified by quantification of IMO and POS phosphorolysis in crude cellular extracts of L. reuteri 100-23. In conclusion, metabolism of IMO by lactobacilli is limited to short-chain oligosaccharides, while bifidobacteria preferentially metabolize oligosaccharides with higher DP. The functionality of commercial IMO can thus be modified by degree of polymerization.

SIGNIFICANCE AND IMPACT OF THE STUDY

Isomalto-oligosaccharides (IMO) are applied as functional food ingredients, but the composition and biological functionality of current commercial products are poorly documented. This study is the first to analyse IMO metabolism by Lactobacillus reuteri. Bifidobacteria were used for comparison. Commercial IMO contained IMO with degree of polymerization (DP) of up to four and panose-series oligosaccharides with DP of up to 5. L. reuteri preferentially metabolized short-chain oligosaccharides, whereas bifidobacteria preferentially metabolized higher oligosaccharides. Results of this study allow the modification of the biological and technological functionality of commercial IMO by adjustment of the degree of polymerization and will thus facilitate the application development for IMO.

Metabolism of oligosaccharides and starch in lactobacilli: a review

Oligosaccharides, compounds that are composed of 2-10 monosaccharide residues, are major carbohydrate sources in habitats populated by lactobacilli. Moreover, oligosaccharide metabolism is essential for ecological fitness of lactobacilli. Disaccharide metabolism by lactobacilli is well understood; however, few data on the metabolism of higher oligosaccharides are available. Research on the ecology of intestinal microbiota as well as the commercial application of prebiotics has shifted the interest from (digestible) disaccharides to (indigestible) higher oligosaccharides. This review provides an overview on oligosaccharide metabolism in lactobacilli. Emphasis is placed on maltodextrins, isomalto-oligosaccharides, fructo-oligosaccharides, galacto-oligosaccharides, and raffinose-family oligosaccharides. Starch is also considered. Metabolism is discussed on the basis of metabolic studies related to oligosaccharide metabolism, information on the cellular location and substrate specificity of carbohydrate transport systems, glycosyl hydrolases and phosphorylases, and the presence of metabolic genes in genomes of 38 strains of lactobacilli. Metabolic pathways for disaccharide metabolism often also enable the metabolism of tri- and tetrasaccharides. However, with the exception of amylase and levansucrase, metabolic enzymes for oligosaccharide conversion are intracellular and oligosaccharide metabolism is limited by transport. This general restriction to intracellular glycosyl hydrolases differentiates lactobacilli from other bacteria that adapted to intestinal habitats, particularly Bifidobacterium spp.

A new method to screen polysaccharide cleavage enzymes

The activity of polysaccharide cleavage enzymes has usually been evaluated by qualitative plate screening methods and quantitative colorimetric or chromatographic assays. The recent development of protein engineering has shown the limits of these techniques when applied to high throughput screening. Here we propose a microplate method to measure the activity of polysaccharide cleavage enzymes through small variations in viscosity. Polysaccharide solutions are co-incubated with magnetic particles in enzyme buffers. The cleavage action of polymer-degrading enzymes increases the mobility of the particles in a magnetic field, even at low levels of enzyme activities. This reproducible, sensitive technique was used to evaluate enzymatic specificity towards substrates. BioFilm indices (BFI) determined by associated software were used to follow enzyme kinetics and measure the usual variables.