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Xylanase
Terms modified by Xylanase Selected AbstractsOptimization of extraction of bulk enzymes from spent mushroom compostJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2003Avneesh D Singh Abstract The profiling of ligninase, hemicellulase and cellulase of Pleurotus sajor-caju after inoculation of spawn in bags containing sawdust was done at monthly intervals for a period of 6 months. Xylanase (EC 3.2.1.8) was produced throughout the 6 months studied with the productivity range from 5.60 to 7.51 U g,1. Cellulase (EC 3.2.1.4) and ,-glucosidase (EC 3.2.1.21) productivities were highest at 4 months, producing 3.31 U g,1 and 121.13 U g,1 respectively. Laccase (EC 1.10.3.2) productivity was highest at 2 months with a value of 7.59 U g,1. Lignin peroxidase (EC 1.11.1.14) productivity was highest at 5 months with a value of 206.20 U g,1. Total soluble proteins were highest at 4 months with a value of 0.139 mg cm,3. The profiling of lignin peroxidase in 5-month-old spent mushroom compost was monitored over a period of 10 months. It was observed that lignin peroxidase was produced throughout the period but productivity was variable. The average lignin peroxidase productivity ranged from 30 to 110 U g,1. The activities of the enzymes extracted in tap water at pH 8.4 were comparable to that extracted in 50 mmol sodium citrate buffer at pH 4.8 and distilled water at pH 5.2 at 4 °C using an incubator shaker at 200 rpm for 18 h. The optimum extraction time was 1 h using an incubator shaker at 4 °C. When an incubator shaker was used, there was no significant difference in the recovery of xylanase, cellulase and laccase at different pH values at 4 °C and 28 °C. No significant difference was observed in the recovery of ,-glucosidase using an incubator shaker at different pH values at 4 °C although the enzyme recovery was slightly higher at pH 8.12, with a value of 29.27 U g,1. The optimum extraction of ,-glucosidase was at pH 4 at room temperature using an incubator shaker. For the lignin peroxidase enzyme, the optimum pH for extraction was 6 at 4 °C and pH 7 at room temperature using an incubator shaker at 200 rpm for 1 h. Homogenization for 8 min at 8000 rpm using tap water at pH 4 had an advantage over the use of the incubator shaker for the extraction as high titers of enzymes were recovered. Copyright © 2003 Society of Chemical Industry [source] Correlative analysis of Mycosphaerella graminicola pathogenicity and cell wall-degrading enzymes produced in vitro: the importance of xylanase and polygalacturonasePLANT PATHOLOGY, Issue 1 2007M.-N. Douaiher Eight Mycosphaerella graminicola isolates were investigated for correlations between pathogenicity and the in vitro production of cell wall-degrading enzymes. Isolate pathogenicity was evaluated in terms of lesion and production of pycnidia in wheat leaves. Additionally, the isolates were compared over time for their ability to produce in vitro significant levels of xylanase (EC 3·2·1·8), ,-xylosidase (EC 3·2·1·37), ,-1,3-glucanase (EC 3·2·1·6), cellulose (EC 3·2·1·4) and polygalacturonase (EC 3·2·1·15) activities when grown in a liquid medium. Correlation tests and principal component analysis revealed a significant correlation between the in vitro production of xylanase and pectinase and pathogenicity components. Xylanase was correlated to necrosis frequency (r = 0·795), ,-xylosidase was correlated to the mean of the lesion length (r = ,0·787), whereas polygalacturonase was correlated to the time when 50% of the leaves contained a lesion (r = 0·776), the lesion frequency (r = 0·646) and the time when 50% of the leaves showed pycnidia (r = ,0·711). The results suggest that these two groups of cell wall-degrading enzymes are therefore likely to be key determinants of pathogenicity in M. graminicola. [source] Process Development in Biotechnology , A Re-EvaluationENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 1 2005K. Schügerl Abstract This review considers some process development problems in biotechnology and presents examples of solutions, which were developed in cooperation with industrial partners. These processes include the production of restriction endonuclease EcoRI by recombinant Escherichia coli, which is toxic to the cell, penicillin V by Penicillium chrysogenum, xylanase by Aspergillus awamori, cephalosporin C by Acremonium chrysogenum, erythritol by Moniliella tomentosa var pollinis, and alkaline serine protease by Bacillus licheniformis. Special attention is given to the practical aspects of product development. [source] Functional importance of Asp37 from a family 11 xylanase in the binding to two proteinaceous xylanase inhibitors from wheatFEMS MICROBIOLOGY LETTERS, Issue 1 2004Tariq A. Tahir Abstract Aspergillus niger xylanase is a target enzyme of the two wheat proteinaceous inhibitors, XIP-I and TAXI-I. We previously suggested that the xylanase "thumb" region was XIP-I binding site. Here, we expressed the Asp37Ala mutant in Pichia pastoris and showed that the mutation abolished the enzyme capacity to interact with both inhibitors, suggesting a direct contact at the active site. The mutant pH profile was altered, confirming the key role of Asp37 in determining the pH optima of glycoside hydrolase family 11. The results are consistent with a competitive inhibition mode and underline the strategic importance of Asp37 in the inhibition mechanism. [source] Thermomyces lanuginosus: properties of strains and their hemicellulasesFEMS MICROBIOLOGY REVIEWS, Issue 1 2003Suren Singh Abstract The non-cellulolytic Thermomyces lanuginosus is a widespread and frequently isolated thermophilic fungus. Several strains of this fungus have been reported to produce high levels of cellulase-free ,-xylanase both in shake-flask and bioreactor cultivations but intraspecies variability in terms of ,-xylanase production is apparent. Furthermore all strains produce low extracellular levels of other hemicellulases involved in hemicellulose hydrolysis. Crude and purified hemicellulases from this fungus are stable at high temperatures in the range of 50,80°C and over a broad pH range (3,12). Various strains are reported to produce a single xylanase with molecular masses varying between 23 and 29 kDa and pI values between 3.7 and 4.1. The gene encoding the T. lanuginosus xylanase has been cloned and sequenced and is shown to be a member of family 11 glycosyl hydrolases. The crystal structure of the xylanase indicates that the enzyme consists of two ,-sheets and one ,-helix and forms a rigid complex with the three central sugars of xyloheptaose whereas the peripheral sugars might assume different configurations thereby allowing branched xylan chains to be accepted. The presence of an extra disulfide bridge between the ,-strand and the ,-helix, as well as to an increase in the density of charged residues throughout the xylanase might contribute to the thermostability. The ability of T. lanuginosus to produce high levels of cellulase-free thermostable xylanase has made the fungus an attractive source of thermostable xylanase with potential as a bleach-boosting agent in the pulp and paper industry and as an additive in the baking industry. [source] Heterologous expression of a Clostridium minicellulosome in Saccharomyces cerevisiaeFEMS YEAST RESEARCH, Issue 8 2009Mariska Lilly Abstract The yeast Saccharomyces cerevisiae was genetically modified to assemble a minicellulosome on its cell surface by heterologous expression of a chimeric scaffoldin protein from Clostridium cellulolyticum under the regulation of the phosphoglycerate kinase 1 (PGK1) promoter and terminator regulatory elements, together with the ,-xylanase 2 secretion signal of Trichoderma reesei and cell wall protein 2 (Cwp2) of S. cerevisiae. Fluorescent microscopy and Far Western blot analysis confirmed that the Scaf3p is targeted to the yeast cell surface and that the Clostridium thermocellum cohesin domain is functional in yeast. Similarly, functionality of the C. thermocellum dockerin domain in yeast is shown by binding to the Scaf3 protein in Far Western blot analysis. Phenotypic evidence for cohesin,dockerin interaction was also established with the detection of a twofold increase in tethered endoglucanase enzyme activity in S. cerevisiae cells expressing the Scaf3 protein compared with the parent strain. This study highlights the feasibility to future design of enhanced cellulolytic strains of S. cerevisiae through emulation of the cellulosome concept. Potentially, Scaf3p-armed yeast could also be developed into an alternative cell surface display strategy with various tailor-made applications. [source] Use of enzyme to improve the technological quality of a panettone like baked productINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 12 2009Walter Benejam Summary The aim of this work was to study the influence of amylase, xylanase and lypase on quality parameters of panettone. Two concentrations of each enzyme were utilised. Besides, enzymes were added to dough or to sponge in order to analyse the effect of the time at which the enzymes were added on bread quality. Results showed that enzymes improved the quality of the product. Depending on the enzyme, the effect was more remarkable on bread height, cell distribution or crumb texture. Particularly, lipase and amylase increased bread height and decreased bread hardness. Although xylanase did not modify bread height, it produced better grain crumb structure and changed the amount of water needed for dough development. Results were different when the additive was incorporated in sponge or in dough. Variability of effects and changes in the results depend both on the doses and on the time of incorporation, all of which provide opportunities to optimise the quality of panettone using a combination of enzymes. [source] Effects of ,-glucanase and xylanase supplementation on gastrointestinal digestive enzyme activities of weaned piglets fed a barley-based dietJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 2 2009C. L. Fan Summary The effects of supplementing a barley-based diet for weaned piglets with exogenous ,-glucanase and xylanase on gastrointestinal digestive enzyme activities were investigated. Thirty-six cross-bred weaned piglets were randomly assigned to two groups with three pens based on sex and mass. Each group was fed on the diet based on barley with or without added ,-glucanase and xylanase (0.15%) for a 4-week period. The results showed that enzyme supplementation improved growth performance of piglets significantly (p < 0.05), but had no effect (p = 0.091) on average daily feed intake. The results also showed that supplementation of ,-glucanase and xylanase had no effect on pepsin activity in gastric contents but slightly decreased (p = 0.092) the pepsin activity in gastric mucosa. Meanwhile, no effect of enzyme supplementation on trypsin activity in duodenal contents was observed. However, the activities of amylase and lipase in duodenal contents were significantly (p < 0.05) decreased, whereas the activities of maltase, sucrase and ,-glutamyl transpeptidase (,-GT) in jejunal and ileal mucosa were enhanced significantly (p < 0.05). The improvement of disaccharidase and ,-GT activity may be attributed to the positive impacts of exogenous enzymes on digestion and absorption of the nutrients. In conclusion, the current results indicated that supplementation with enzymes in barley-based diets could improve the growth performance of piglets, decrease the activities of amylase and lipase in duodenal contents and increase the activities of disaccharidase and ,-GT in jejunal and ileal mucosa. [source] Supplementation of xylanase and phospholipase to wheat-based diets for weaner pigsJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 9-10 2005G. Diebold Summary The effects of supplementing a wheat-based diet for weaner pigs with exogenous xylanase and phospholipase on ileal and faecal nutrient digestibilities and on the level of microbial metabolites in ileal digesta were examined. Fourteen piglets, weaned at 11 days, were fitted with a simple T-cannula at the distal ileum. The pigs were offered a control diet or diets supplemented with xylanase and phospholipase individually or in combination, in a two period crossover design. The combination of xylanase and phospholipase tended to increase the ileal recovery of the amino sugar galactosamine, whereas the concentration expressed in mg/kg dry matter intake of glucosamine was slightly decreased (p < 0.10). There was neither an effect of enzyme supplementation on ileal and faecal digestibility of the other nutrients and energy, nor was there an effect on pH and on the level of microbial metabolites in ileal digesta. However, an increase in ileal and faecal nutrient and energy digestibility with increasing age was observed. The ileal and faecal digestibility coefficients (except for ether extract) were significantly (p < 0.05) higher in experimental period I than in period II. These higher values may be attributed to a lower feed intake during period I. Since a lower level of feed intake is generally associated with a slower rate of passage and a longer retention time of digesta, a positive impact on digestion and absorption of nutrients can be assumed, which, on the other hand, limits the potential of additional enzyme effects. [source] Untersuchungen zum Einfluß einer Xylanaseergänzung in Legehennenrationen auf Weizenbasis 2.JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 1-2 2000Mitteilung: Auswirkungen auf die Leistungsparameter Summary The influence of a xylanase supplement on performance of laying hens fed different energy-graded, wheat-based rations was tested in a 12-week trial. Two varieties of wheat with different extraction viscosity were selected. In addition to the control ration, three test rations with reduced energy contents of ,3, ,6, and ,9% were used. Sixteen groups, each consisting of 30 hens were kept in single cages. At the beginning of the experiment hens were 24 weeks old. Single eggmass and daily eggmass production showed a statistically significant difference. This was not caused by the enzyme supplement or the energy content, but by the variety of wheat. Interaction effects between variety of wheat, enzyme supplement and energy content became obvious with regard to the yolk colour. The influence of the enzyme on the yolk colour is positive and statistically highly significant. Thus, the addition of xylanase to wheat-based rations does not affect the performance parameters of laying hens positively. Zusammenfassung In einem zwölfwöchigem Leistungsversuch wurde der Einfluß einer Xylanaseergänzung in Legehennenrationen auf Weizenbasis mit abgestuftem Energiegehalt auf die Leistungsparameter untersucht. Dazu wurden zwei Weizensorten (Alidos + Caprimus) mit unterschiedlicher Extraktviskosität ausgesucht und neben den jeweiligen Kontrollrationen drei Versuchsrationen mit abgestuftem Energiegehalt (,3%, ,6%, ,9%) eingesetzt. Den 16 Versuchsgruppen waren jeweils 30 Legehennen zugeordnet, die bei Versuchsbeginn 24 Lebenswochen alt waren. Es handelte sich um eine Einzelkäfigaufstallung. Statistisch signifikante Unterschiede ergaben sich bei der Einzeleimasse und der täglichen Eimasseproduktion, die sich jedoch weder dem Enzymzusatz noch dem Energiegehalt zuordnen ließen, sondern durch die Weizensorte bedingt waren. Es zeigten sich Wechselwirkungen zwischen Weizensorte, Enzymsupplementierung und Energiegehalt auf die Dotterfarbe. Es war ein statistisch hochsignifikanter positiver Enzymeinfluß auf die Dotterfarbe zu erkennen. Insgesamt gesehen, zeigte sich auch in diesem Legehennenversuch keine positive Wirkung der Xylanaseergänzung auf die Leistungsparamter zu Rationen auf Weizenbasis. [source] pH Control of the production of recombinant glucose oxidase in Aspergillus nidulansJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2004R. Luque Abstract Aims:, Recombinant Aspergillus nidulans sVAL040, capable of synthesizing and secreting glucose oxidase derived from Aspergillus niger was used to study the influence of pH and carbon source on enzyme production. Methods and Results:, Glucose oxidase gene (goxC) was expressed under transcriptional regulation by using the promoter of A. nidulans xlnB gene (encoding an acidic xylanase). A maximum specific glucose oxidase activity of approx. 10 U mg,1 protein and a maximum volumetric productivity of 29·9 U l,1 h,1 were obtained at pH 5·5, after 80 h of growth by using xylose as inducer. Enzyme volumetric productivity increased when xylans were used instead of xylose; however, specific glucose oxidase activity did not differ significantly. Conclusions:, Specific GOX activity obtained at pH 5·5 are two to three times more than those previously described for goxC multicopy transformants of A. nidulans. Xylans were a more powerful inducer than xylose although fungal growth was lower when the polymers were used. Significance and Impact of the Study:, The obtained results by using xlnB promoter in A. nidulans could be useful in improving heterologous enzyme production by using genetic- and process-engineering strategies. [source] Influence of ciliate protozoa on biochemical changes and hydrolytic enzyme profile in the rumen ecosystemJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2002A. Santra Aims:,To assess the effect of presence or absence of rumen protozoa on fermentation characteristics and enzyme profile in growing lambs. Methods and Results:,Weaner lambs (G1, G2, G3, G4, G5 and G6 groups) were defaunated by oral administration of sodium laurel sulphate (at 8 g 100 kg,1 body weight). The lambs of G4, G5 and G6 groups were refaunated. The roughage and concentrate ratio in the diet of G1 and G4, G2 and G5, and G3 and G6 were 50:50 (R1), 65:35 (R2) and 80:20 (R3), respectively. Daily dry matter intake was similar in defaunated and faunated lambs. However, digestibility of organic matter (OM), cellulose and gross energy were lower in defaunated lambs while crude protein (CP) digestibility was similar in both defaunated and faunated lambs. The rumen pH and NH3 -N were lower (P < 0·01) while TVFA, total-N and TCA-ppt-N were higher (P < 0·01), in defaunated lambs. Ruminal activity of carboxymethyl cellulase was lower (P < 0·01) in defaunated lambs and amylase, xylanase, protease and urease were similar in faunated and defaunated lambs. Nutrient utilization, rumen metabolites and ciliate protozoal count were higher, whereas digestibility of fibre fractions was lower in high rather than low concentrate fed lambs. The rumen protozoa present before defaunation were B-type and the protozoa which re-established on refaunation were also B-type. Conclusions:,Absence of ciliate protozoa decreased nutrient digestibility and increased ruminal TVFA and total-N with lower NH3 -N concentration, indicating better energy and protein utilization in defaunated lambs. Significance and Impact of the Study: Defaunation improved energy and protein utilization in lambs. [source] Isolation and chemical structure characterization of enzymatic lignin from Populus deltoides woodJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2010Ali Abdulkhani Abstract Cellulytic enzymes were used for the isolation and structural characterization of Populus deltoides wood lignin as a fast growing and important species in wood processing technology. The isolation was based on the hydrolysis and partial solubilization of wood xylan and cellulose using combination of Thricoderma lanuginosus xylanase, Aspergillus sp. plus, A. niger cellulase, and almond glycosidase, followed by lignin purification using Bacillus licheniformis alkaline protease (for hydrolysis of cellulase contamination). The structure of enzymatic lignin (EL) was elucidated using chemical analysis, Py-GC/MS, FTIR, and quantitative 13C-NMR techniques. Different lignin structures of acetylated and nonacetylated lignin preparation were calculated. P. deltoides EL has been determined to have an h : g : s ratio of 5 : 60 : 35. Also, P. deltoides EL contained 0.59/Ar of ,-O-4 moieties with small amounts of other structural units such as pino/syringyresinol (0.05/Ar), phenylcoumaran (0.05/Ar), and spirodienone (0.01/Ar). The degree of condensation was estimated at 20%. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Xylanolytic complex from Aspergillus giganteus: production and characterizationJOURNAL OF BASIC MICROBIOLOGY, Issue 4 2003Glauciane Danusa Coelho An Aspergillus giganteus strain was isolated as an excellent producer of xylanase associated with low levels of cellulase. Optimal xylanase production was obtained in liquid Vogel medium containing xylan as carbon source, pH 6.5 to 7.0, at 25 °C and under shaking at 120 rpm during 84h. Among the several carbon sources tested, higher xylanase production was verified in xylan, xylose, sugar-cane bagasse, wheat bran and corn cob cultures, respectively. Optimal conditions for activity determination were 50 °C and pH 6.0. The xylanolytic complex of A. giganteus showed low thermal stability with T50 of 2 h, 13 min and 1 min when it was incubated at 40, 50 and 60 °C, respectively, and high stability from pH 4.5 to 10.5, with the best interval between 7.0 to 7.5. This broad range of stability in alkali pH indicates a potential applicability in some industrial processes, which require such condition. Xylanolytic activity of A. giganteus was totally inhibited by Hg+2, Cu+2 and SDS at 10 mM. The analysis of the products from the oat spelts xylan hydrolysis through thin-layer chromatography indicated endoxylanase activity, lack of debranching enzymes and ,-xylosidase activity in assay conditions. [source] Effect of xylanase on ozone bleaching kinetics and properties of Eucalyptus kraft pulpJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 10 2003M Blanca Roncero Abstract Environmental pressure has led the pulp and paper industry to develop new technologies in order to reduce or suppress the presence of various pollutants in effluents from bleaching plants. One of the choices for this purpose is enzyme-based biotechnology. This study deals with the effect of using a xylanase-based enzymatic pretreatment, in a TCF (Totally Chlorine Free) sequence, on the properties of the resulting paper pulps. The hexenuronic acid content in the pulp and the physical properties of the paper were also studied. The performance of the xylanase was analysed through kinetic studies on ozone bleaching. The enzymatic pretreatment results in easier bleaching and delignification of the pulp, causing a bleach-boosting effect. The decreased consumption of reagent is related to a decreased content of hexenuronic groups. The physical properties of the treated pulp are similar to those of untreated pulps. Cellulose degradation, delignification and chromophores' removal show first-order kinetics. Enzyme pretreatment leads to differences between the kinetic constants of cellulose degradation and chromophores' removal, due to an increased accessibility to bleaching agents. The xylanase treatment leads to a lower floor kappa number (IK,) during the ozone stage. Copyright © 2003 Society of Chemical Industry [source] Optimization of extraction of bulk enzymes from spent mushroom compostJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2003Avneesh D Singh Abstract The profiling of ligninase, hemicellulase and cellulase of Pleurotus sajor-caju after inoculation of spawn in bags containing sawdust was done at monthly intervals for a period of 6 months. Xylanase (EC 3.2.1.8) was produced throughout the 6 months studied with the productivity range from 5.60 to 7.51 U g,1. Cellulase (EC 3.2.1.4) and ,-glucosidase (EC 3.2.1.21) productivities were highest at 4 months, producing 3.31 U g,1 and 121.13 U g,1 respectively. Laccase (EC 1.10.3.2) productivity was highest at 2 months with a value of 7.59 U g,1. Lignin peroxidase (EC 1.11.1.14) productivity was highest at 5 months with a value of 206.20 U g,1. Total soluble proteins were highest at 4 months with a value of 0.139 mg cm,3. The profiling of lignin peroxidase in 5-month-old spent mushroom compost was monitored over a period of 10 months. It was observed that lignin peroxidase was produced throughout the period but productivity was variable. The average lignin peroxidase productivity ranged from 30 to 110 U g,1. The activities of the enzymes extracted in tap water at pH 8.4 were comparable to that extracted in 50 mmol sodium citrate buffer at pH 4.8 and distilled water at pH 5.2 at 4 °C using an incubator shaker at 200 rpm for 18 h. The optimum extraction time was 1 h using an incubator shaker at 4 °C. When an incubator shaker was used, there was no significant difference in the recovery of xylanase, cellulase and laccase at different pH values at 4 °C and 28 °C. No significant difference was observed in the recovery of ,-glucosidase using an incubator shaker at different pH values at 4 °C although the enzyme recovery was slightly higher at pH 8.12, with a value of 29.27 U g,1. The optimum extraction of ,-glucosidase was at pH 4 at room temperature using an incubator shaker. For the lignin peroxidase enzyme, the optimum pH for extraction was 6 at 4 °C and pH 7 at room temperature using an incubator shaker at 200 rpm for 1 h. Homogenization for 8 min at 8000 rpm using tap water at pH 4 had an advantage over the use of the incubator shaker for the extraction as high titers of enzymes were recovered. Copyright © 2003 Society of Chemical Industry [source] Improvement of a fed-batch process for high level xylanase production by a Bacillus strainJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2001Gerhard Schneider Abstract In this paper, the improvement of a fed-batch fermentation from the point of view of an industrial xylanase production process is described. The Bacillus strain chosen for this study is able to produce high quantities of a xylanase that is suitable to be used as bleach boost agent in chlorine-free bleaching sequences of paper pulp. It was found that xylo-oligosaccharides (hydrolysis products from xylan by xylanase action) were indispensable for induction of the enzyme synthesis, but that their presence in quantities of only 0.1,g,dm,3 xylose equivalents led to catabolite repression. A substrate-limited fed-batch process, that is the most adapted, was furthermore improved with regard to nutrient requirement of the microorganism, especially the nitrogen source. A process with constant supply of a culture medium containing xylan, peptone and mineral nitrogen was able to produce 20,240,nkat,cm,3 with a productivity of 910,nkat,cm,3,h,1, which places the process among the best ever reported. © 2001 Society of Chemical Industry [source] OPTIMIZATION OF NEW FLOUR IMPROVER MIXING FORMULA BY SURFACE RESPONSE METHODOLOGYJOURNAL OF FOOD PROCESS ENGINEERING, Issue 2 2010RAOUDHA ELLOUZE GHORBEL ABSTRACT In the present study, we search to improve the viscoelastic properties of wheat flour characterized by a low bread-making quality. Six regulators were tested: broad bean flour, gluten, monodiglyceride (MDG), ascorbic acid, sodium alginate and a mixture of amylase and xylanase. A hybrid design was carried out in order to study the effect of these regulators on the alveographic properties of wheat flour dough. Two alveographic responses (W: deformation energy and P/L: elasticity-to-extensibility ratio) were studied and simultaneously optimized via the desirability functions. An optimal mixture, containing 13.17 g/kg of broad bean flour, 15.13 g/kg of gluten, 0.155 g/kg of ascorbic acid, 3.875 g/kg of MDG, 2.75 g/kg of sodium alginate and 0.3 g/kg of enzyme mixture, was obtained and tested in a Tunisian flour. It led to a dough characterized by a W = 274 × 10,4 J and P/L = 0.74 versus 191 × 10,4 J and 0.40, respectively, for the Tunisian flour without improvers. PRACTICAL APPLICATIONS In this work, we developed a new flour improver mixing formula intended to be used with wheat flour characterized by a low bread-making quality. This improver mixture is in powder form and contains 13.17 g of broad bean flour, 15.13 g of gluten, 0.155 g of ascorbic acid, 3.875 g of monodiglyceride, 2.75 g of sodium alginate and 0.3 g of enzyme mixture per kilogram of wheat flour. The incorporation of this improver mixture in low bread-making quality wheatflour leads to an increase of its deformation energy (W) of about 43% and produces large volume bread. [source] INHIBITION OF STALING IN CHAPATI (INDIAN UNLEAVENED FLAT BREAD)JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 3 2008IRSHAD M. SHAIKH ABSTRACT Chapati is an unleavened Indian flat bread made from whole wheat flour usually consumed immediately after preparation as it becomes hard on keeping because of staling. Large-scale mechanized preparation of ready-to-eat chapatis will have to address this problem. Investigations were made to study the effect of sodium stearoyl-2-lactylate (SSL), glycerol monostearate, propylene glycol, sorbitol, ,-amylase, xylanase, maltodextrin and guar gum when added to chapati dough, on the inhibition of staling in chapatis stored at 29 ± 1C and 4 ± 1C. Chapatis were prepared from whole wheat flour dough containing (salt, 5% oil, appropriate preservatives and the aforementioned additives. Chapatis were packed in self-sealing low-density polyethylene bags and were stored for 10 days at 29 ± 1C and 4 ± 1C. Stored chapatis were analyzed for various staling parameters such as moisture content, texture, water-soluble starch, in vitro enzyme digestibility, enthalpy change (,H) and sensory quality. Staling of chapatis at 29 ± 1C and at 4 ± 1C of storage was inhibited by all additives to different extents; the extent of staling was less at 4 ± 1C. Maltodextrin at 0.3% (w/w) was found to be the most effective. Several combinations of additives were also studied, and the best combination was (100 ppm) + SSL (0.375%) levels. PRACTICAL APPLICATIONS Chapati, a traditional staple food of Indians, is unleavened flat bread made from whole wheat flour. With rapidly changing lifestyles, changing socio-economic trends and increasing urbanization and consumerism there is a rising demand for convenience foods which require minimum or no preparation time particularly the ready-to-eat (RTE) type of foods. Chapatis are generally baked fresh twice a day for lunch and dinner, and unless eaten immediately after baking, these stale rapidly and become difficult to chew. The most important parameter of chapati quality is its texture. The texture is generally evaluated in terms of tenderness, flexibility and its suitability to be folded into a spoon shape for eating with curried preparation. RTE chapatis are the latest addition to the species of "convenience foods." Keeping this in mind the research was undertaken to improve quality of chapati with the addition of various additives and improvements for the inhibition of staling in chapati. [source] Development of a Sensitive Serological Method for Specific Detection of Latent Infection of Macrophomina phaseolina in CowpeaJOURNAL OF PHYTOPATHOLOGY, Issue 1 2009Leonard Afouda Abstract A double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) was developed for the specific detection and quantification of Macrophomina phaseolina in plant tissue. Both polyclonal antisera produced against immunogens from mycelium and culture filtrate of M. phaseolina detected the fungus in mycelial and plant extracts, although the antibodies raised against mycelium were more sensitive. No cross-reaction occurred with Rhizopus stolonifer, Pythium ultimum, Mucor hiemalis, Fusarium oxysporum, Septoria nodorum, Rhizoctonia solani, Sclerotinia sclerotiorum, Phytophthora infestans and Aspergillus niger. In enzyme assays, activity of the endo-acting hydrolytic enzymes 1,3-,-glucanase and, less, cellulase, but not xylanase was detected in infected plants. DAS-ELISA was more sensitive than the 1,3-,-glucanase assay. In polyacrylamide gel electrophoresis (PAGE) up to 18 protein bands were observed, with four bands occurring in the 12 tested isolates deriving from various geographical origin in Niger and Nigeria. The enzyme assays and protein patterns were considered not suitable for specific M. phaseolina detection. Macrophomina phaseolina was essentially located in the roots and hypocotyls, and less in epicotyls and leaves of infected plants. The antibodies were also useful to detect latent infection and the infection of cowpea seeds. [source] Effect of fibrolytic enzymes and an inoculant on in vitro degradability and gas production of low-dry matter alfalfa silageJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2008Lazar K Kozelov Abstract BACKGROUND: The objective of this study was to investigate the effect of polysaccharide-degrading enzymes (a cellulase and a xylanase) alone or in a combination with a bacterial inoculant on fermentation parameters and in vitro degradability and gas production of low-dry matter (DM) alfalfa silage. First cut alfalfa (Medicago sativa L.), harvested at about 5% bloom stage [260 g kg,1 dry matter (DM)] was ensiled in laboratory-scale silos without preservatives or preserved with formic acid, a cellulase (Cell), a xylanase, a cellulose/xylanase enzyme combination (Cell/Xyl), a lactic acid bacteria-based inoculant (Inoc), and a mix of Inoc and Cell (Inoc/Cell). Triplicate silos were opened on days 1, 3, 7, 15 and 60. RESULTS: Silage pH and ammonia N and total free amino acids concentrations were the lowest (P < 0.05) for the formic acid silage. Inoc and Inoc/Cell produced the highest (P < 0.05) lactate concentration in the 60-day silage. In vitro degradability of silage DM was not affected (P = 0.998) by treatment, but amylase-treated neutral detergent fiber degradability was increased (P < 0.05) by formic acid. Compared with the control (51.3 mL 100 mg,1 silage DM), all treatments except Cell/Xyl increased (P < 0.001) the 24 h cumulative gas production. CONCLUSIONS: Overall, enzyme and lactic acid bacteria-based preparations had minor effects on silage fermentation in this experiment. The increased cumulative gas production indicates some preservation or liberation of fermentable organic matter with most treatments tested. It is not clear, however, to what extent this effect would impact silage ruminal degradability in vivo. Copyright © 2008 Society of Chemical Industry [source] Evaluation of baking procedures for incorporation of barley roller milling fractions containing high levels of dietary fibre into breadJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 4 2008Morrison S Jacobs Abstract BACKGROUND: Roller milling of hull-less barley generates fibre-rich fractions (FRF) enriched in non-starch polysaccharides from the endosperm cell walls (,-glucans and arabinoxylans). This investigation was initiated to compare the suitability of different baking processes and to determine the optimal conditions for incorporation of barley FRF into pan bread. RESULTS: Addition of FRF from waxy and high-amylose starch hull-less barley genotypes was evaluated in pan bread prepared from Canada Western Red Spring (CWRS) and Canada Western Extra Strong (CWES) wheat flour. Three bread processes were used: Canadian short process (CSP), remix-to-peak, and sponge-and-dough. Addition of 20% FRF (equivalent to enrichment with 4.0 g of arabinoxylans and ,-glucans per 100 g of flour) disrupted dough properties and depressed loaf volume. CSP was not suitable for making FRF-enriched bread because dough could not be properly developed. FRF-enriched remix-to-peak bread was better, especially for the stronger CWES flour. The better bread quality compared to CSP was probably due to redistribution of water from non-starch polysaccharides to gluten during fermentation prior to remixing and final proof. The sponge-and-dough process produced the best FRF-enriched bread because of the positive effect of sponge fermentation on gluten development and hydration. FRF was added at the dough stage to fully developed dough. CONCLUSION: The method of bread production strongly influences bread quality. Pre-hydration of FRF improved bread quality. CWRS and CWES flour produced comparable FRF-enriched sponge-and-dough bread. Addition of xylanase to the sponge-and-dough formula improved the loaf volume, appearance, crumb structure and firmness of FRF-enriched bread. Copyright © 2007 Society of Chemical Industry [source] Effect of adding an anaerobic fungal culture isolated from a wild blue bull (Boselophus tragocamelus) to rumen fluid from buffaloes on in vitro fibrolytic enzyme activity, fermentation and degradation of tannins and tannin-containing Kachnar tree (Bauhinia variegata) leaves and wheat strawJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 2 2006Shyam S Paul Abstract The study investigated the effects of adding an anaerobic fungus (Piromyces sp FNG5; isolated from the faeces of a wild blue bull) to the rumen fluid of buffaloes consuming a basal diet of wheat straw and concentrates on in vitro enzyme activities, fermentation and degradation of tannins and tannin-rich tree leaves and wheat straw. In experiment 1, strained rumen fluid was incubated for 24 and 48 h, in quadruplicate, with or without fungal culture using condensed tannin-rich Bauhinia variegata leaves as substrates. In experiment 2, in vitro incubation medium containing wheat straw and different concentrations of added tannic acid (0,1.2 mg mL,1) were incubated for 48 h, in quadruplicate, with strained buffalo rumen fluid with or without fungal culture. In experiment 3, tolerance of the fungal isolate to tannic acid was tested by estimating fungal growth in pure culture medium containing different concentrations (0,50 g L,1) of tannic acid. In in vitro studies with Bauhinia variegata tree leaves, addition of the fungal isolate to buffalo strained rumen liquor resulted in significant (P < 0.01) increase in neutral detergent fibre (NDF) digestibility and activities of carboxymethyl cellulase (P < 0.05) and xylanase (P < 0.05) at 24 h fermentation. There was 12.35% increase (P < 0.01) in condensed tannin (CT) degradation on addition of the fungal isolate at 48 h fermentation. In in vitro studies with wheat straw, addition of the fungus caused an increase in apparent digestibility (P < 0.01), true digestibility (P < 0.05), NDF digestibility (P < 0.05), activities of carboxymethyl cellulase (P < 0.001), ,-glucosidase (P < 0.001), xylanase (P < 0.001), acetyl esterase (P < 0.001) and degradation of tannic acid (P < 0.05). Rumen liquor from buffaloes which had never been exposed to tannin-containing diet had been found to have substantial inherent tannic acid-degrading ability (degraded 55.3% of added tannic acid within 24 h of fermentation). The fungus could tolerate tannic acid concentration up to 20 g L,1 in growth medium. The results of this study suggest that introduction of an anaerobic fungal isolate with superior lignocellulolytic activity isolated from the faeces of a wild herbivore may improve fibre digestion from tannin-containing feeds and degradation of tannins in the rumen of buffaloes. Copyright © 2005 Society of Chemical Industry [source] Production and partial characterization of cellulase free xylanase by Bacillus subtilis C 01 using agriresidues and its application in biobleaching of nonwoody plant pulpsLETTERS IN APPLIED MICROBIOLOGY, Issue 5 2007M. Ayyachamy Abstract Aims:, To optimize the solid-state cultivation conditions for xylanase production using agriresidues and testing the biobleaching efficiency of xylanase on nonwoody plant fibre materials. Methods and Results:, An extracellular cellulase free xylanase was produced from Bacillus subtilis C 01 using various inexpensive substrates under solid-state cultivation. High level of xylanase production (135 IU gds,1) was observed when grown on wheat bran followed by maize powder (50 IU gds,1). The maximum xylanase (136 IU gds,1) production was occurred in wheat bran-to-moisture ratio of 1 : 1 at 72 h. The xylanase pretreated pulp samples of banana, silk cotton and cotton showed an increased brightness of 19·6, 11·6 and 7·9%, respectively. Conclusions:, The enzyme-aided biobleaching results indicate that the xylanase has potential application in enhancing the brightness of nonwoody plant fibre pulp. Significance and Impact of the Study:, This is the first report on biobleaching of banana fibres, silk cotton and cotton pulps using xylanase. The biobleaching results of secondary fibres are promising and can be transferred to paper mills, which utilize nonwoody plant fibres as a raw material for paper production. [source] Correlative analysis of Mycosphaerella graminicola pathogenicity and cell wall-degrading enzymes produced in vitro: the importance of xylanase and polygalacturonasePLANT PATHOLOGY, Issue 1 2007M.-N. Douaiher Eight Mycosphaerella graminicola isolates were investigated for correlations between pathogenicity and the in vitro production of cell wall-degrading enzymes. Isolate pathogenicity was evaluated in terms of lesion and production of pycnidia in wheat leaves. Additionally, the isolates were compared over time for their ability to produce in vitro significant levels of xylanase (EC 3·2·1·8), ,-xylosidase (EC 3·2·1·37), ,-1,3-glucanase (EC 3·2·1·6), cellulose (EC 3·2·1·4) and polygalacturonase (EC 3·2·1·15) activities when grown in a liquid medium. Correlation tests and principal component analysis revealed a significant correlation between the in vitro production of xylanase and pectinase and pathogenicity components. Xylanase was correlated to necrosis frequency (r = 0·795), ,-xylosidase was correlated to the mean of the lesion length (r = ,0·787), whereas polygalacturonase was correlated to the time when 50% of the leaves contained a lesion (r = 0·776), the lesion frequency (r = 0·646) and the time when 50% of the leaves showed pycnidia (r = ,0·711). The results suggest that these two groups of cell wall-degrading enzymes are therefore likely to be key determinants of pathogenicity in M. graminicola. [source] Production, purification and characterisation of a novel halostable xylanase from Bacillus sp.ANNALS OF APPLIED BIOLOGY, Issue 2 2010NTU-0 Bacillus sp. NTU-06 was used to produce xylanase, which is an important industrial enzyme used in the pulp and paper industry. The enzyme was purified by fast protein liquid chromatography (FPLC) and had a molecular mass of 24 kDa. The enzyme was active over a concentration range of 0,20% sodium chloride in culture broth, although its activity was optimal in 5% sodium chloride. A salinity stability test showed that 43% of the enzyme activity was retained after 4 h in 20% sodium chloride. Xylanase activity was maximal at pH 8.0 and 40°C. The enzyme was somewhat thermostable, retaining 20% of the original activity after incubation at 70°C for 4 h. The xylanase had Km and Vmax values of 3.45 mg mL,1 and 387.3 µmol min,1mg,1, respectively. The deduced internal amino acid sequence of Bacillus sp. NTU-06 xylanase resembled the sequence of beta-1,4-endoxylanase, which is a member of glycoside hydrolase family 11. Some of the novel characteristics that make this enzyme potentially effective in xylan biodegradation are discussed. [source] A dipicolinate lanthanide complex for solving protein structures using anomalous diffractionACTA CRYSTALLOGRAPHICA SECTION D, Issue 7 2010Guillaume Pompidor Tris-dipicolinate lanthanide complexes were used to prepare derivative crystals of six proteins: hen egg-white lysozyme, turkey egg-white lysozyme, thaumatin from Thaumatococcus daniellii, urate oxidase from Aspergillus flavus, porcine pancreatic elastase and xylanase from Trichoderma reesei. Diffraction data were collected using either synchrotron radiation or X-rays from a laboratory source. In all cases, the complex turned out to be bound to the protein and the phases determined using the anomalous scattering of the lanthanide led to high-quality electron-density maps. The binding mode of the complex was characterized from the refined structures. The lanthanide tris-dipicolinate was found to bind through interactions between carboxylate groups of the dipicolinate ligands and hydrogen-bond donor groups of the protein. In each binding site, one enantiomeric form of the complex is selected from the racemic solution according to the specific site topology. For hen egg-white lysozyme and xylanase, derivative crystals obtained by cocrystallization belonged to a new monoclinic C2 crystal form that diffracted to high resolution. [source] Structure,specificity relationships of an intracellular xylanase from Geobacillus stearothermophilusACTA CRYSTALLOGRAPHICA SECTION D, Issue 8 2007V. Solomon Geobacillus stearothermophilus T-6 is a thermophilic Gram-positive bacterium that produces two selective family 10 xylanases which both take part in the complete degradation and utilization of the xylan polymer. The two xylanases exhibit significantly different substrate specificities. While the extracellular xylanase (XT6; MW 43.8,kDa) hydrolyzes the long and branched native xylan polymer, the intracellular xylanase (IXT6; MW 38.6,kDa) preferentially hydrolyzes only short xylo-oligosaccharides. In this study, the detailed three-dimensional structure of IXT6 is reported, as determined by X-ray crystallography. It was initially solved by molecular replacement and then refined at 1.45,Å resolution to a final R factor of 15.0% and an Rfree of 19.0%. As expected, the structure forms the classical (,/,)8 fold, in which the two catalytic residues (Glu134 and Glu241) are located on the inner surface of the central cavity. The structure of IXT6 was compared with the highly homologous extracellular xylanase XT6, revealing a number of structural differences between the active sites of the two enzymes. In particular, structural differences derived from the unique subdomain in the carboxy-terminal region of XT6, which is completely absent in IXT6. These structural modifications may account for the significant differences in the substrate specificities of these otherwise very similar enzymes. [source] Crystallization and preliminary X-ray analysis of a novel Trichoderma reesei xylanase IV belonging to glycoside hydrolase family 5ACTA CRYSTALLOGRAPHICA SECTION D, Issue 3 2004Tarja Parkkinen Xylanase IV (XYN IV) is a new recently characterized xylanase from Trichoderma reesei. It is able to degrade several different xylans, mainly producing xylose. XYN IV has been crystallized by the hanging-drop vapour-diffusion method, using PEG 6000 as a precipitant. The crystals belong to the orthorhombic space group P212121, with unit-cell parameters a = 86.3, b = 137.5, c = 196.1,Å, , = , = , = 90°. Assuming a molecular weight of 50.3,kDa, the VM values indicate there to be four XYN IV monomers in an asymmetric unit and the solvent content of the crystals to be 57%. Based on dynamic light-scattering measurements, XYN IV is a dimer in solution. A native data set to 2.8,Å resolution has been collected at a home laboratory and a data set to 2.2,Å resolution has been collected using synchrotron radiation. [source] A new crystal form of XT6 enables a significant improvement of its diffraction quality and resolutionACTA CRYSTALLOGRAPHICA SECTION D, Issue 3 2004Maya Bar Xylanases (1,4-,- d -xylan xylanhydrolases; EC 3.2.1.8) hydrolyze the 1,4-,- d -xylopyranosyl linkage of xylans. The detailed structural characterization of these enzymes is of interest for the elucidation of their catalytic mechanism and for their rational modification toward improved stability and specificity. An extracellular xylanase from Geobacillus stearothermophilus T-6 (XT6) has recently been cloned, overexpressed, purified and biochemically characterized. Previous crystallographic efforts resulted in a hexagonal crystal form, which subsequently proved to be of limited use for structural analysis, mainly because of its relatively poor diffraction quality and resolution. A systematic search for more suitable crystals of XT6 recently resulted in a new crystal form of this enzyme with significantly improved diffraction characteristics. The new crystals belong to a C -centred monoclinic crystal system (space group C2), with unit-cell parameters a = 121.5, b = 61.7, c = 89.1,Å, , = 119.7°. These crystals diffract X-rays to better than 1.5,Å resolution, showing a very clear diffraction pattern of relatively high quality. The crystals are mechanically strong and exhibit excellent radiation-stability when frozen under cold nitrogen gas. A full diffraction data set to 1.45,Å resolution (94.1% completeness, Rmerge = 7.0%) has been collected from flash-frozen crystals of the native enzyme at 95,K using synchrotron radiation. Crystals of the E159A/E265A catalytic double mutant of XT6 were found to be isomorphous to those of native XT6. They were used for a full measurement of 1.8,Å resolution diffraction data at 100,K (90.9% completeness; Rmerge = 5.0%). These data are currently being used for the high-resolution structure determination of XT6 and its mutant for mechanistic interpretations and rational introduction of thermostability. [source] | |||||||||||||||||||||||||||||||