The Experts below are selected from a list of 4125 Experts worldwide ranked by ideXlab platform
Michael A. Cotta - One of the best experts on this subject based on the ideXlab platform.
-
Identification of a broad-specificity xylosidase/arabinosidase important for Xylooligosaccharide fermentation by the ruminal anaerobe Selenomonas ruminantium GA192.
Current microbiology, 2001Co-Authors: Terence R. Whitehead, Michael A. CottaAbstract:Strains of Selenomonas ruminantium vary considerably in their capacity to ferment Xylooligosaccharides. This ability ranges from strain GA192, which completely utilized xylose through xylotetraose and was able to ferment considerable quantities of larger oligosaccharides, to strain HD4, which used only the simple sugars present in the hydrolysate. The ability of S. ruminantium GA192 to utilize Xylooligosaccharides was correlated with the presence of xylosidase and arabinosidase activities. The production of these activities appears to be regulated in response to carbon source used for growth. Both arabinosidase and xylosidase were induced by growth on xylose or Xylooligosaccharides, but no activity was detected in glucose-or arabinose-grown cultures. A genetic locus from S. ruminantium GA192 was cloned into Escherichia coli JM83 that produced both xylosidase and arabinosidase activities. Analyses of crude extracts from the E. coli clone and S. ruminantium GA192 by using native polyacrylamide gel electrophoresis and methylumbelliferyl substrates indicated that a single protein was responsible for both activities. The enzyme expressed in E. coli was capable of degrading Xylooligosaccharides derived from xylan. DNA sequencing of the locus demonstrated the presence of an open reading frame that encodes for a protein of 61,174 molecular weight.
-
identification of a broad specificity xylosidase arabinosidase important for Xylooligosaccharide fermentation by the ruminal anaerobe selenomonas ruminantium ga192
Current Microbiology, 2001Co-Authors: Terence R. Whitehead, Michael A. CottaAbstract:Strains of Selenomonas ruminantium vary considerably in their capacity to ferment Xylooligosaccharides. This ability ranges from strain GA192, which completely utilized xylose through xylotetraose and was able to ferment considerable quantities of larger oligosaccharides, to strain HD4, which used only the simple sugars present in the hydrolysate. The ability of S. ruminantium GA192 to utilize Xylooligosaccharides was correlated with the presence of xylosidase and arabinosidase activities. The production of these activities appears to be regulated in response to carbon source used for growth. Both arabinosidase and xylosidase were induced by growth on xylose or Xylooligosaccharides, but no activity was detected in glucose-or arabinose-grown cultures. A genetic locus from S. ruminantium GA192 was cloned into Escherichia coli JM83 that produced both xylosidase and arabinosidase activities. Analyses of crude extracts from the E. coli clone and S. ruminantium GA192 by using native polyacrylamide gel electrophoresis and methylumbelliferyl substrates indicated that a single protein was responsible for both activities. The enzyme expressed in E. coli was capable of degrading Xylooligosaccharides derived from xylan. DNA sequencing of the locus demonstrated the presence of an open reading frame that encodes for a protein of 61,174 molecular weight.
-
Xylooligosaccharide utilization by the ruminal anaerobic bacterium Selenomonas ruminantium.
Current microbiology, 1998Co-Authors: Michael A. Cotta, Terence R. WhiteheadAbstract:Fermentation of Xylooligosaccharides by 11 strains of Selenomonas ruminantium was examined. Xylooligosaccharides were prepared by the partial hydrolysis of oat spelt xylan in dilute phosphoric acid (50 mM, 121°C, 15 min) and were added to a complex, yeast extract-Trypticase-containing medium. Strains of S. ruminantium varied considerably in their capacity to ferment Xylooligosaccharides. Strains GA192, GA31, H18, and D used arabinose, xylose, and the oligosaccharides xylobiose through xylopentaose, as well as considerable quantities of larger, unidentified oligosaccharides. Other strains of S. ruminantium (HD4, HD1, 20-21a, H6a, W-21, S23, 5-1) were able to use only the simple sugars present in the substrate mixture. The ability of S. ruminantium strains to utilize Xylooligosaccharides was correlated with the presence of xylosidase and arabinosidase activities. Both enzyme activities were induced by growth on Xylooligosaccharides, but no activity was detected in glucose- or arabinose-grown cultures. Xylooligosaccharide-fermenting strains of S. ruminantium exhibited considerable variation in substrate utilization patterns, and the assimilation of individual carbohydrate species also appeared to be regulated. Lactic, acetic, and propionic acids were the major fermentation end products detected.
-
Xylooligosaccharide utilization by the ruminal anaerobic bacterium Selenomonas ruminantium.
Current microbiology, 1998Co-Authors: Michael A. Cotta, Terence R. WhiteheadAbstract:Fermentation of Xylooligosaccharides by 11 strains of Selenomonas ruminantium was examined. Xylooligosaccharides were prepared by the partial hydrolysis of oat spelt xylan in dilute phosphoric acid (50 mM, 121 degrees C, 15 min) and were added to a complex, yeast extract-Trypticase-containing medium. Strains of S. ruminantium varied considerably in their capacity to ferment Xylooligosaccharides. Strains GA192, GA31, H18, and D used arabinose, xylose, and the oligosaccharides xylobiose through xylopentaose, as well as considerable quantities of larger, unidentified oligosaccharides. Other strains of S. ruminantium (HD4, HD1, 20-21a, H6a, W-21, S23, 5-1) were able to use only the simple sugars present in the substrate mixture. The ability of S. ruminantium strains to utilize Xylooligosaccharides was correlated with the presence of xylosidase and arabinosidase activities. Both enzyme activities were induced by growth on Xylooligosaccharides, but no activity was detected in glucose- or arabinose-grown cultures. Xylooligosaccharide-fermenting strains of S. ruminantium exhibited considerable variation in substrate utilization patterns, and the assimilation of individual carbohydrate species also appeared to be regulated. Lactic, acetic, and propionic acids were the major fermentation end products detected.
-
Degradation and utilization of xylan by the ruminal bacteria Butyrivibrio fibrisolvens and Selenomonas ruminantium.
Applied and environmental microbiology, 1995Co-Authors: Michael A. Cotta, R L ZeltwangerAbstract:The cross-feeding of xyland hydrolysis products between the xylanolytic bacterium Butyrivibrio fibrisolvens H17c and the Xylooligosaccharide-fermenting bacterium Selenomonas ruminantium GA192 was investigated. Cultures were grown anaerobically in complex medium containing oat spelt xylan, and the digestion of xylan and the generation and subsequent utilization of Xylooligosaccharide intermediates were monitored over time. Monocultures of B. fibrisolvens rapidly degraded oat spelt xylan, and a pool of extracellular degradation intermediates composed of low-molecular-weight Xylooligosaccharides (xylobiose through xylopentaose and larger, unidentified oligomers) accumulated in these cultures. The ability of S. ruminantium to utilize the products of xylanolysis by B. fibrisolvens was demonstrated by its ability to grow on xylan that had first been digested by the extracellular xylanolytic enzymes of B. fibrisolvens. Although enzymatic hydrolysis converted the xylan to soluble products, this alone was not sufficient to assure complete utilization by S. ruminantium, and considerable quantities of oligosaccharides remained following growth. Stable xylan-utilizing cocultures of S. ruminantium and B. fibrisolvens were established, and the utilization of xylan was monitored. Despite the presence of an oligosaccharide-fermenting organism, accumulations of acid-alcohol soluble products were still noted; however, the composition of carbohydrates present in these cultures differed from that seen when B. fibrisolvens was cultivated alone. Residual carbohydrates present at various times during growth were of higher average degree of polymerization in cocultures than in cultures of B. fibrisolvens alone. Structural characterization of these residual products may help define the limitations on the assimilation of Xylooligosaccharides by ruminal bacteria.
Xin Zhou - One of the best experts on this subject based on the ideXlab platform.
-
A novel recyclable furoic acid-assisted pretreatment for sugarcane bagasse biorefinery in co-production of Xylooligosaccharides and glucose.
Biotechnology for biofuels, 2021Co-Authors: Lin Dai, Huang Tian, Kankan Jiang, Xin ZhouAbstract:BACKGROUND Pretreatment is the key step for utilizing lignocellulosic biomass, which can extract cellulose from lignin and disrupt its recalcitrant crystalline structure to allow much more effective enzymatic hydrolysis; and organic acids pretreatment with dual benefic for generating Xylooligosaccharides and boosting enzymatic hydrolysis has been widely used in adding values to lignocellulose materials. In this work, furoic acid, a novel recyclable organic acid as catalyst, was employed to pretreat sugarcane bagasse to recover the Xylooligosaccharides fraction from hemicellulose and boost the subsequent cellulose saccharification. RESULTS The FA-assisted hydrolysis of sugarcane bagasse using 3% furoic acid at 170 °C for 15 min resulted in the highest Xylooligosaccharides yield of 45.6%; subsequently, 83.1 g/L of glucose was harvested by a fed-batch operation with a solid loading of 15%. Overall, a total of 120 g of Xylooligosaccharides and 335 g glucose could be collected from 1000 g sugarcane bagasse starting from the furoic acid pretreatment. Furthermore, furoic acid can be easily recovered by cooling crystallization. CONCLUSION This work put forward a novel furoic acid pretreatment method to convert sugarcane bagasse into Xylooligosaccharides and glucose, which provides a strategy that the sugar and nutraceutical industries can be used to reduce the production cost. The developed process showed that the yields of Xylooligosaccharides and byproducts were controllable by shortening the reaction time; meanwhile, the recyclability of furoic acid also can potentially reduce the pretreatment cost and potentially replace the traditional mineral acids pretreatment.
-
An integrated biorefinery process for adding values to corncob in co-production of Xylooligosaccharides and glucose starting from pretreatment with gluconic acid.
Bioresource technology, 2020Co-Authors: Jian Han, Rou Cao, Xin ZhouAbstract:Increasing attention has been paid to the production of high value-added products from lignocellulosic biomass. This study aims to valorize corncob, utilizing it as feedstock for a multi-biorefinery framework, using gluconic acid in the pretreatment. In attempts to maximize yield of Xylooligosaccharides, corncob was first subjected to hydrolysis by gluconic acid using response surface methodology, from which the maximum Xylooligosaccharides yield of 56.2% was achieved using 0.6 mol/L gluconic acid at 154 °C for 47 min. Results indicated that gluconic acid was an effective solvent for Xylooligosaccharides production: a total of 180 g of Xylooligosaccharides was obtained from 1 kg corncob as a result of hydrolysis. Moreover, 86.3% conversion of cellulose was achieved from enzymatic hydrolysis of gluconic acid-treated corncob at 10% solids loading. This study presents a strategy for valorizing corncob using it to produce Xylooligosaccharides and glucose, which should pave the way for valorizing other agriculture wastes.
-
An eco-friendly biorefinery strategy for Xylooligosaccharides production from sugarcane bagasse using cellulosic derived gluconic acid as efficient catalyst.
Bioresource technology, 2019Co-Authors: Xin Zhou, Jianglin Zhao, Xiaotong ZhangAbstract:Abstract A novel approach was proposed for the production of Xylooligosaccharides by direct pre-hydrolysis using gluconic acid as catalyst. Maximum Xylooligosaccharides (degree of polymerization 2–6) yield of 53.2% could be obtained in 60 min through 5% gluconic acid hydrolysis of sugarcane bagasse at 150 °C. Furthermore, the yield of glucose from solids following gluconic acid hydrolysis treatment was 86.2% after fed-batch enzymatic hydrolysis with 10% solids loading. Results indicated that gluconic acid pretreatment combined with enzymatic hydrolysis could be successfully applied to sugarcane bagasse substrate. Subsequently, glucose could be efficiently bio-oxidized to gluconic acid by Gluconobacter oxydans ATCC 621H with 93.1% yield, and sugarcane bagasse derived gluconic acid has been proved to be an effective catalyst for Xylooligosaccharides production. In this study, Xylooligosaccharides production from sugarcane bagasse by gluconic acid hydrolysis demonstrated a great potential with respect to the production of these probiotics around the world.
Juan Carlos Parajó - One of the best experts on this subject based on the ideXlab platform.
-
Membrane-assisted processing of Xylooligosaccharide-containing liquors.
Journal of agricultural and food chemistry, 2006Co-Authors: Rodolfo Vegas, Herminia Domínguez, José Luis Alonso, Susana Luque, José R. Álvarez, Juan Carlos ParajóAbstract:Liquors from rice husk autohydrolyis, containing Xylooligosaccharides, other saccharides, and nonsaccharide compounds, were subjected to two selected processing schemes to increase the proportion of substituted Xylooligosaccharides in refined liquors. Nanofiltration through a ceramic membrane with a molecular mass cutoff of 1000 Da allowed simultaneous concentration and purification; this latter derived from the preferential removal of monosaccharides and nonsaccharide compounds. When liquors were nanofiltered to achieve a volume reduction factor of 5 operating at a transmembrane pressure of 14 bar, 58.6% of the nonsaccharide components and 20.9-46.9% of monosaccharides were kept in retentate, in comparison with 92% of Xylooligosaccharides and glucooligosaccharides. When nanofiltered liquors were subjected to double ion-exchange processing, a final product with a nonsaccharide content near 9 kg/100 kg of nonvolatile components was obtained at a yield of 10.90 kg/100 kg oven dry rice husks. Alternatively, when nanofiltered liquors were subjected to ethyl acetate extraction and further double ion-exchange processing, a purified product with a nonsaccharide content of 5.66 kg/100 kg of nonvolatile components was obtained at a yield of 9.94 kg/100 kg oven dry rice husks. The nonsaccharide components remaining in the final concentrate were mainly made up of phenolic and nitrogen-containing compounds.
-
Refining of autohydrolysis liquors for manufacturing Xylooligosaccharides: evaluation of operational strategies
Bioresource technology, 2005Co-Authors: Manuel Vázquez, Gil Garrote, Herminia Domínguez, José Luis Alonso, Juan Carlos ParajóAbstract:When xylan-containing lignocellulosic materials are subjected to the action of heat in an aqueous medium (autohydrolysis reaction) under suitable operational conditions, the heterocyclic ether bonds of the polymeric chain are split to give Xylooligosaccharides (XO) and a variety of other products derived from hemicelluloses, lignin and extractives. For product applications requiring high-purity XO, subsequent purification stages have to be implemented. Various strategies have been evaluated for refining Eucalyptus wood autohydrolysis liquors, including the two-stage reaction, precipitation and solvent extraction of freeze-dried, dewaxed liquors. Data on the degree of Xylooligosaccharide recovery as well as on the composition of the isolates (measured in terms of hemicellulose-derived products and non-saccharide products) are provided for the various operational procedures assayed.
-
Production of Xylooligosaccharides by autohydrolysis of lignocellulosic materials
Trends in Food Science and Technology, 2003Co-Authors: Juan Carlos Parajó, Gil Garrote, José Manuel Cruz, Herminia DomínguezAbstract:The composition of xylan-containing raw materials (Eucalyptus globulus wood, corn cobs, rice husks and barley husks) has been determined, and substituted Xylooligosaccharides (SXO) have been produced by reacting them with water (autohydrolysis reaction) under optimal conditions deduced from reported kinetic models. The composition of autohydrolysis liquors (defined by their contents of Xylooligosaccharides, other sugar oligomers, monosaccharides, acetyl and uronic acid substituents of oligomers, free acetic acid, furfural, Folin-Denis phenols and other compounds) has been determined. The suitability of autohydrolysis reaction products for the manufacture of food ingredients is discussed.
-
Xylooligosaccharides: manufacture and applications
Trends in Food Science & Technology, 2000Co-Authors: María José Vázquez, Herminia Domínguez, José Luis Alonso, Juan Carlos ParajóAbstract:Xylooligosaccharides (sugar oligomers made up of xylose units) are useful for a variety of purposes. This article reviews the production of Xylooligosaccharides from lignocellulosic materials (by chemical or enzymatic methods) and the purification of the end products, as well as their application as food ingredients, with special attention to the beneficial effects caused on health by these types of compounds.
-
Mild autohydrolysis: an environmentally friendly technology for Xylooligosaccharide production from wood
Journal of Chemical Technology & Biotechnology, 1999Co-Authors: Gil Garrote, Herminia Domínguez, Juan Carlos ParajóAbstract:Eucalyptus globulus wood samples were subjected to hydrothermal treatments under mild operational conditions (145–190 ° C, liquor to solid ratio 6–10 g g−1, reaction times up to 7.5 h). Residual xylan, Xylooligosaccharides, other sugars, furfural, glucan and lignin contents were determined. Negligible effects were caused by hydrothermal treatments on both cellulose and lignin. Kinetic models were developed which describe the hydrolysis of hemicelluloses. Xylan degradation, Xylooligosaccharide and xylose generation, and xylose dehydration to furfural were accurately described by models based on pseudohomogeneous, first-order kinetics with Arrhenius-type temperature dependence. These models are useful for a technical evaluation of this environmentally friendly technology. © 1999 Society of Chemical Industry
Amit Arora - One of the best experts on this subject based on the ideXlab platform.
-
Green and clean process to obtain low degree of polymerisation Xylooligosaccharides from almond shell
Journal of Cleaner Production, 2019Co-Authors: Ramkrishna D. Singh, Cresha Gracy Nadar, Jane G. Muir, Amit AroraAbstract:Abstract This work presents a green and chemical free sequential process consisting of autohydrolysis, enzymatic treatment, and membrane assisted refining for the valorization of almond shell into the low degree of polymerisation Xylooligosaccharides. For autohydrolysis, the temperatures (180, 200, and 220 °C) with different reaction times were evaluated. Further, enzymatic treatment of the autohydrolysate was performed to increase the concentration of low degree of polymerisation Xylooligosaccharides. For enzymatic treatment, three different doses (5, 10, and 15 U) was used, and the optimum dose estimated using statistical analysis. Finally, the XOS rich enzyme liquor was subjected to membrane assisted refining using 1 kDa and 250 Da membranes to obtain XOS concentrate. Under the optimal condition (200 °C, 5 min) of autohydrolysis, about 54.5% of xylan could be obtained as oligosaccharides. However, the autohydrolysate was composed of 3.5% (w/w of biomass) of low degree of polymerisation Xylooligosaccharides (xylobiose and xylotriose). The enzymatic treatment using 10 U of the enzyme could increase the concentration of low degree of polymerisation Xylooligosaccharides to 8.2% (w/w of biomass). Finally, the membrane-assisted refining could recover 69.1 ± 0.1% (w/w) of produced Xylooligosaccharides.
-
Prebiotic potential of oligosaccharides: A focus on xylan derived oligosaccharides
Bioactive Carbohydrates and Dietary Fibre, 2015Co-Authors: Ramkrishna Singh, Jhumur Banerjee, Amit AroraAbstract:Abstract Xylan is available abundantly in nature as a major constituent of hemicellulose, a component of lignocellulosic biomass. Agricultural wastes such as straw, stalk, cob, hull, husk, bagasse and pulp of hardwood represent a major source of xylan. Xylooligosaccharides (XOS), the hydrolysis product of xylan is substrate for colonic commensal bacterial population, acting as potential prebiotic. Its fermentation produces short chain fatty acids, improves gut epithelial health and regulates metabolic process. These oligosaccharides possess bound phenolics including ferulic acid, coumaric acid, thus imparting additional antioxidant effect and immunomodulatory activity. This paper deals with xylan based oligosaccharides with an emphasis placed on the need of oligosaccharides and discusses in detail the health benefits of Xylooligosaccharides.
Isao Kusakabe - One of the best experts on this subject based on the ideXlab platform.
-
Preparation of (1→4)-β-d-Xylooligosaccharides from an acid hydrolysate of cotton-seed xylan: suitability of cotton-seed xylan as a starting material for the preparation of (1→4)-β-d-Xylooligosaccharides
Carbohydrate research, 2002Co-Authors: Hyeon Jin Sun, Shigeki Yoshida, Nyun Ho Park, Isao KusakabeAbstract:Cotton-seed residual cake, which is a byproduct of the process of oil extraction from the seed, was delignified with sodium hypochlorite (1% available chlorine). Xylan was then prepared from the delignified wet material by alkali extraction with 15% sodium hydroxide. The cotton-seed xylan contained 64.7% xylose and 9.4% uronic acid. The xylan was hydrolyzed with 0.125 M sulfuric acid at 90 °C for 15 min. The resultant hydrolysis products were separated by gel-permeation chromatography on BioGel P-4 and Toyopearl HW-40F columns connected in series, with water as an eluate. Xylose and Xylooligosaccharides with a degree of polymerization ranging from DP 2 to 15 were separated under such conditions, and each Xylooligosaccharide-containing peak fraction afforded a single band on fluorophore-assisted carbohydrate electrophoresis. These results suggest that cotton-seed xylan is suitable for the preparation of xylose and Xylooligosaccharides.
-
Preparation of (1→4)-β-d-Xylooligosaccharides from an acid hydrolysate of cotton-seed xylan: suitability of cotton-seed xylan as a starting material for the preparation of (1→4)-β-d-Xylooligosaccharides
Carbohydrate research, 2002Co-Authors: Hyeon Jin Sun, Shigeki Yoshida, Nyun Ho Park, Isao KusakabeAbstract:Cotton-seed residual cake, which is a byproduct of the process of oil extraction from the seed, was delignified with sodium hypochlorite (1% available chlorine). Xylan was then prepared from the delignified wet material by alkali extraction with 15% sodium hydroxide. The cotton-seed xylan contained 64.7% xylose and 9.4% uronic acid. The xylan was hydrolyzed with 0.125 M sulfuric acid at 90 degrees C for 15 min. The resultant hydrolysis products were separated by gel-permeation chromatography on BioGel P-4 and Toyopearl HW-40F columns connected in series, with water as an eluate. Xylose and Xylooligosaccharides with a degree of polymerization ranging from DP 2 to 15 were separated under such conditions, and each Xylooligosaccharide-containing peak fraction afforded a single band on fluorophore-assisted carbohydrate electrophoresis. These results suggest that cotton-seed xylan is suitable for the preparation of xylose and Xylooligosaccharides.
