Biosorption of nonylphenol on dead biomass of Rhizopus arrhizus encapsulated in chitosan beads

The nonylphenol (NP) biosorption and desorption potential for fungal biomass used under batch conditions was investigated using kinetics and isotherm models. Fungal biomass of Rhizopus arrhizus TISTR 3610 exhibited preferential uptake of NP, an endocrine disrupting chemicals. Sporangiospores, asexual spores, were immobilisation in chitosan beads. The biosorption data of NP on the moist heat inactivated R. arrhizus-chitosan beads were analyzed using four popular adsorption isotherms and, by using non-linear least-regression with the solver add-in in Microsoft Excel, correlated in order with the Fritz-Schlüender > Redlich-Peterson > Freundlich > Langmuir isotherms. The pseudo first-order kinetics was found to have the best fit with the experimental data. The diffusivity of NP in the R. arrhizus-chitosan beads was calculated using the shrinking core model, and the diffusivity values were in the ranges of 2.3736 x 10^[-4] to 1.8950 x 10^[-4] cm^[2]s^[-1]. Desorption to recover the adsorbed NP from the beads was performed in methanol and was best described using a pseudo second-order kinetic model

Partial depolymerization of tamarind seed xyloglucan and its functionality toward enhancing the solubility of curcumin

Polysaccharides of tamarind seed, a byproduct of the tamarind pulp industry, displayed a potential solubility improvement of lipophilic bioactive molecules but their textural characteristics hinder the dietary formulation. In contrast, the commonly available xyloglucan oligosaccharides (XOSs) with degrees of polymerization (DPs) of 7, 8, and 9 were too short to maintain their ability. The binding capacity of the between sizes is unknown due to a lack of appropriate preparation. We prepared xyloglucan megalosaccharides (XMSs) by partial depolymerization, where term megalosaccharide (MS) defines the middle chain-length saccharide between DPs 10 and 100. Digestion with fungal cellulase enabled reproducible active XMSs. Further identification of pure XMS segments indicated that XMS-B has an average DP of 17.2 (Gal3Glc8Xyl6) with a branched dimer of XOS 8 and 9 and was free of side-chain arabinose, the residue influencing high viscosity. Curcumin, a bioactive pigment, has poor bioavailability because of its water insolubility. XMSs with average DPs of 15.4-24.3 have similarly sufficient capacities to solubilize curcumin. The solubility of curcumin was improved 180-fold by the addition of 50 %, w/ v, XMSs, which yielded a clear yellow liquid. Our findings indicated that XMSs were a promising added-value agent in foods and pharmaceuticals for the oral intake of curcumin

Nonreducing terminal chimeric isomaltomegalosaccharide and its integration with azoreductase for the remediation of soil-contaminated lipophilic azo dyes

Lipophilic azo dyes are practically water-insoluble, and their dissolution by organic solvents and surfactants is harmful to biological treatment with living cells and enzymes. This study aimed to evaluate the feasibility of a newly synthesized nonreducing terminal chimeric isomaltomegalosaccharide (N-IMS) as a nontoxic solubilizer of four simulated lipophilic azo dye wastes for enzymatic degradation. N-IMS bearing a helical α-(1 → 4)-glucosidic segment derived from a donor substrate α-cyclodextrin was produced by a coupling reaction of cyclodextrin glucanotransferase. Inclusion complexing by N-IMS overcame the solubility issue with equilibrium constants of 1786-242 M-1 (methyl yellow > ethyl red > methyl red > azo violet). Circular dichroism spectra revealed the axial alignment of the aromatic rings in the N-IMS cavity, while UV-visible absorption quenching revealed that the azo bond of methyl yellow was particularly induced. Desorption of the dyes from acidic and neutral soils was specific to aqueous organic over alkali extraction. The dissolution kinetics of the incorporated dyes followed a sigmoid pattern facilitating the subsequent decolorization process with azoreductase. It was demonstrated that after soil extraction, the solid dyes dissolved with N-IMS assistance and spontaneously digested by coupled azoreductase/glucose dehydrogenase (for a cofactor regeneration system) with the liberation of the corresponding aromatic amine

Formulation and evaluation of a novel megalomeric microemulsion from tamarind seed xyloglucan-megalosaccharides for improved high-dose quercetin delivery

Megalomeric microemulsion is a new term referring to lipid-based formulation using amphiphilic megalosaccharide as a coexcipient. Quercetin is a dose-dependent bioactive compound and has promising therapeutic potential, but its low water solubility and permeability restrict its treatment efficacy. We aimed to formulate high-dose quercetin loaded into colloidal micelles by the self-micro emulsifying system (SMES) in combination with Tween 80, isopropyl myristate, and xyloglucan megalosaccharide (X-MS). X-MS is a moderate-size heterologous saccharide obtained from enzymatic cleavage of tamarind seed xyloglucan. X-MSs with an average degree of polymerization of 16 and 56 were investigated to bearing their surface hydrophobic interaction with a fluorescence probe 6-(p-toluidino)-2-naphthalene-6-sulfonate yielded the binding constant values of 127 and 180 M-1, respectively and X-MS itself displayed a slight effect on quercetin binding. However, the implementation of X-MSs toward SMES was highly compatible because X-MS molecules were confined in micellular solutions. Consequently, X-MSs improved the quercetin loading from 1 to 2 to 12.5-17.7 mg/mL based on the composition ratio, X-MS chain lengths, and X-MS concentrations (0.15-3.0%, w/v) and stabilized the quercetin-loaded oil-in-water SMES. The optical appearances were transparent yellow containing uniformly fine droplets with diameters of 11-12 nm. In vitro radical scavenging activity tests with 2,2-diphenyl-1-picrylhydrazyl showed that the megalomeric microemulsions improved the half-maximal inhibitory concentration (IC50 = 22-24 μg/mL) over that of the X-MS-free microemulsion. This study provided a new approach of liquid supplementation from commercially unavailable-size xyloglucan to be a promising added-value agent for oral uptake of quercetin

Physicochemical functionality of chimeric isomaltomegalosaccharides with α-(1→4)-glucosidic segments of various lengths

Isomaltomegalosaccharide (IMS) is a long chimeric glucosaccharide composed of alpha-(1-+ 6)-and alpha-(1-+ 4)-linked segments at nonreducing and reducing ends, respectively; the hydrophilicity and hydrophobicity of these segments are expected to lead to bifunctionality. We enzymatically synthesized IMS with average degrees of polymerization (DPs) of 15.8, 19.3, and 23.5, where alpha-(1-+ 4)-segments had DPs of 3, 6, and 9, respectively. IMS exhibited considerably higher water solubility than maltodextrin because of the alpha-(1-+ 6)-segment and an identical resistance to thermal degradation as short dextran. Interaction of IMS with a fluorescent probe of 2-p- toluidinylnaphthalene-6-sulfonate demonstrated that IMS was more hydrophobic than maltodextrin, where the degree of hydrophobicity increased as DP of alpha-(1-+ 4)-segment increased (9 > 6 > 3). Fluorescent pyreneestimating polarity of IMS was found to be similar to that of methanol or 1-butanol. The bifunctional IMS enhanced the water solubility of quercetin-3-O-glucoside and quercetin: the solubilization of less-soluble bioactive substances is beneficial in carbohydrate industry

Characterization of an Unknown Region Linked to the Glycoside Hydrolase Family 17 beta-1,3-Glucanase of Vibrio vulnificus Reveals a Novel Glucan-Binding Domain

The glycoside hydrolase family 17 beta-1,3-glucanase of Vibrio vulnificus (VvGH17) has two unknown regions in the N- and C-termini. Here, we characterized these domains by preparing mutant enzymes. VvGH17 demonstrated hydrolytic activity of beta-(1 -> 3)-glucan, mainly producing laminaribiose, but not of beta-(1 -> 3)/beta-(1 -> 4)-glucan. The C-terminal-truncated mutants (Delta C466 and Delta C441) showed decreased activity, approximately one-third of that of the WT, and Delta C415 lost almost all activity. An analysis using affinity gel containing laminarin or barley beta-glucan revealed a shift in the mobility of the Delta C466, Delta C441, and Delta C415 mutants compared to the WT. Tryptophan residues showed a strong affinity for carbohydrates. Three of four point-mutations of the tryptophan in the C-terminus (W472A, W499A, and W542A) showed a reduction in binding ability to laminarin and barley beta-glucan. The C-terminus was predicted to have a beta-sandwich structure, and three tryptophan residues (Trp472, Trp499, and Trp542) constituted a putative substrate-binding cave. Linker and substrate-binding functions were assigned to the C-terminus. The N-terminal-truncated mutants also showed decreased activity. The WT formed a trimer, while the N-terminal truncations formed monomers, indicating that the N-terminus contributed to the multimeric form of VvGH17. The results of this study are useful for understanding the structure and the function of GH17 beta-1,3-glucanases

Discovery of alpha-L-ucosidase Raises the Possibility of alpha-L-Glucosides in Nature

Glucose, a common monosaccharide in nature, is dominated by the D-enantiomer. Meanwhile, the discovery of L-glucose-utilizing bacteria and the elucidation of their metabolic pathways 10 years ago suggests that L-glucose exists naturally. Most carbohydrates exist as glycosides rather than monosaccharides; therefore, we expected that nature also contains L-glucosides. Sequence analysis within glycoside hydrolase family 29 led us to identify two alpha-L-glucosidases, ClAg129A and ClAg1298, derived from Cecernbia lonarensis LW9. ClAg129A and ClAg129B exhibited higher K-m, k(cat), and k(cat)/K-m values for p-nitrophenyl alpha-L-glucoside than that for p-nitrophenyl alpha-L-fucoside. Structural analysis of ClAg129B in complex with L-glucose showed that these enzymes have an active-site pocket that preferentially binds alpha-L-glucoside, but exdudes alpha-L-fucoside. These results suggest that CIAg129A and ClAg129B evolved to hydrolyze alpha-L-glucoside, implying the existence of alpha-L-glucoside in nature. Furthermore, alpha-L-glucosidic linkages (alpha-L-Glc-(1 -> 3)-L-G1c, alpha-L-Glc-(1 -> 2)-L-Glc, and alpha-L-Glc-(1 -> 6)-L-G1c) were synthesized by the transglucosylation activity of ClAg129A and ClAg129B. We believe that this study will lead to new research on alpha-L-glucosides, including determining the physiological effects on humans, and the discovery of novel alpha-L-ucoside-related enzymes

A novel mechanism for the promotion of quercetin glycoside absorption by megalo α-1,6-glucosaccharide in the rat small intestine

The presence of α-1,6-glucosaccharide enhances absorption of water-soluble quercetin glycosides, a mixture of quercetin-3-O-β-D-glucoside (Q3G, 31.8%), mono (23.3%), di (20.3%) and more D-glucose adducts with α-1,4-linkage to D-glucose moiety of Q3G, in a ligated small intestinal loop of anesthetized rats. We enzymatically prepared α-1,6-glucosaccharides with different degrees of polymerization (DP) and separated them into a megaloisomaltosaccharide-containing fraction (M-IM, average DP = 11.0) and an oligoisomaltosaccharide-containing fraction (O-IM, average DP = 3.6). Luminal injection of either saccharide fractions promoted the absorption of total quercetin-derivatives from the small intestinal segment and this effect was greater for M-IM than O-IM addition. M-IM also increased Q3G, but not the quercetin aglycone, concentration in the water-phase of the luminal contents more strongly than O-IM. The enhancement of Q3G solubilization in the luminal contents may be responsible for the increases in the quercetin glucoside absorption promoted by α-1,6-glucosaccharides, especially M-IM. These results suggest that the ingestion of α-1,6-glucosaccharides promotes Q3G bioavailability

A practical approach to producing isomaltomegalosaccharide using dextran dextrinase from Gluconobacter oxydans ATCC 11894

Dextran dextrinase (DDase) catalyzes formation of the polysaccharide dextran from maltodextrin. During the synthesis of dextran, DDase also generates the beneficial material isomaltomegalosaccharide (IMS). The term megalosaccharide is used for a saccharide having DP=10-100 or 10-200 (DP, degree of polymerization). IMS is a chimeric glucosaccharide comprising alpha-(1 -> 6)- and alpha-(1 -> 4)-linked portions at the nonreducing and reducing ends, respectively, in which the alpha-(1 -> 4)-glucosyl portion originates from maltodextrin of the substrate. In this study, IMS was produced by a practical approach using extracellular DDase (DDext) or cell surface DDase (DDsur) of Gluconobacter oxydans ATCC 11894. DDsur was the original form, so we prepared DDext via secretion from intact cells by incubating with 0.5% G6/G7 (maltohexaose/maltoheptaose); this was followed by generation of IMS from various concentrations of G6/G7 substrate at different temperatures for 96 h. However, IMS synthesis by DDext was limited by insufficient formation of alpha-(1 -> 6)-glucosidic linkages, suggesting that DDase also catalyzes elongation of alpha-(1 -> 4)-glucosyl chain. For production of IMS using DDsur, intact cells bearing DDsur were directly incubated with 20% G6/G7 at 45 degrees C by optimizing conditions such as cell concentration and agitation efficiency, which resulted in generation of IMS (average DP =14.7) with 61% alpha-(1 -> 6)-glucosyl content in 51% yield. Increases in substrate concentration and agitation efficiency were found to decrease dextran formation and increase IMS production, which improved the reaction conditions for DDext. Under modified conditions (20% G6/G7, agitation speed of 100 rpm at 45 degrees C), DDext produced IMS (average DP =14.5) with 65% alpha-(1 -> 6)-glucosyl content in a good yield of 87%