Xylanase

About: Xylanase is a research topic. Over the lifetime, 7099 publications have been published within this topic receiving 163793 citations.

Interactions between dietary fat type and xylanase supplementation when rye-based diets are fed to broiler chickens. 1. Physico-chemical chyme features.

Abstract: 1. The interactions between fat type and xylanase supplementation of rye-based diets were investigated using a 2 x 2 factorial design in which a rye-based diet (610 g rye/kg) was combined with 100 g/kg of soya oil or beef tallow, with and without xylanase supplementation at 3000 IU/kg, and fed to 1-d-old male broilers. Food passage time, viscosity of digesta supernatant, xylanase activity and pH in different segments of the digestive tract were examined. 2. Food passage throughout the digestive tract was accelerated by enzyme addition regardless of fat type. The time taken for 50% of the marker to be excreted was reduced from 8.4 to 6.7 h in animals receiving the rye-soya oil diets and from 8.0 to 6.9 h with the rye-tallow diets. 3. Viscosity in the supernatant of the jejunal and ileal digesta was markedly decreased after enzyme addition. Viscosities were generally higher in the ileal than in the jejunal supernatant, and fell as the birds aged from 14 to 28 d. The effect of enzyme was also reduced in older chicks. There was not a clear effect of the fat source on viscosity. 4. Xylanase activity was still found at the end of the ileum in digesta of birds fed on the enzyme-supplemented diets but not in control animals. Xylanase activity was also detected in the caeca of all groups. 5. Significantly lower pH values were found in tallow-fed birds in some segments of the digestive tract. A significant increase in pH after enzyme addition was detected in the proximal ileum; this was independent of fat source.

Amino acid supplementation improves heterologous protein production by Saccharomyces cerevisiae in defined medium

Abstract: Supplementation of a chemically defined medium with amino acids or succinate to improve heterologous xylanase production by a prototrophic Saccharomyces cerevisiae transformant was investigated. The corresponding xylanase production during growth on ethanol in batch culture and in glucose-limited chemostat culture were quantified, as the native ADH2 promoter regulating xylanase expression was derepressed under these conditions. The addition of a balanced mixture of the preferred amino acids, Ala, Arg, Asn, Glu, Gln and Gly, improved both biomass and xylanase production, whereas several other individual amino acids inhibited biomass and/or xylanase production. Heterologous protein production by the recombinant yeast was also improved by supplementing the medium with succinate. The production of heterologous xylanase during growth on ethanol or glucose could thus be improved by supplementing metabolic precursors in the carbon- or nitrogen-metabolism.

Lignocellulose-Adapted Endo-Cellulase Producing Streptomyces Strains for Bioconversion of Cellulose-Based Materials.

Abstract: Twenty-four Actinobacteria strains, isolated from Arundo donax, Eucalyptus camaldulensis and Populus nigra biomasses during natural biodegradation and with potential enzymatic activities specific for the degradation of lignocellulosic materials, were identified by a polyphasic approach. All strains belonged to Streptomyces (S.) genus and in particular, the most representative species was S. argenteolus including the 50% of strains; while 8 strains were identified as members of species S. flavogriseus (synonym S. flavovirens) and S. fimicarius (synonyms S. acrimycini, S. baarnensis, S. caviscabies and S. flavofuscus), and the other 4 strains belonged to the species S. drozdowiczii, S. rubrogriseus, S. albolongus and S. ambofaciens. Moreover, all Streptomyces strains, tested for endo and exo-cellulase, cellobiase, xylanase, pectinase, ligninase, peroxidase and laccase activities using qualitative and semi-quantitative methods on solid growth medium, exhibited multi-enzymatic activities (from three to six). The twenty-four strains were further screened for endo-cellulase activity in liquid growth medium and the four best endo-cellulase producers (S. argenteolus AE58P, S. argenteolus AE710A, S. argenteolus AE82P and S. argenteolus AP51A) were subjected to partial characterization and their enzymatic crude extracts adopted to perform saccharification experiments of Arundo donax pretreated biomass. The different degrees of cellulose and xylan hydrolysis was evaluated by determining the kinetics of glucose and xylose release during 72 h incubation at 50°C of the pretreated biomass in the presence of cellulose degrading enzymes (cellulase and β-glucosidase) and xylan related activities (xylanase and β-xylosidase). Cellulose and xylan conversion, when conducted using commercial (hemi)cellulolytic, gave glucose and xylose yields of 30.17% and 68.9%, respectively. The replacement of the cellulolytic preparation from Genencor (Accellerase 1500), with the endo-cellulase from S. argenteolus AE58P allowed to reach almost the 76% of the glucose yield obtained in the presence of the commercial counterpart. Due to the promising results obtained by using the enzymatic crude extracts from S. argenteolus AE58P in the pretreated A. donax saccharification experiments, the proteins putatively responsible for endo-cellulase activity in this strain were identified by proteomics. Overall results highlighted the biotechnological potential of S. argenteolus AE58P being an interesting candidate biocatalysts-producing bacterium for the lignocellulose conversion and biochemicals and bioenergy production.

Production, purification and characterization of Bacillus sp. GRE7 xylanase and its application in eucalyptus Kraft pulp biobleaching

Abstract: Production of extracellular xylanase from Bacillus sp GRE7 using a bench-top bioreactor and solid-state fermentation (SSF) was attempted SSF using wheat bran as substrate and submerged cultivation using oat-spelt xylan as substrate resulted in an enzyme productivity of 3,950 IU g−1 bran and 180 IU ml−1, respectively The purified enzyme had an apparent molecular weight of 42 kDa and showed optimum activity at 70°C and pH 7 The enzyme was stable at 60–80°C at pH 7 and pH 5–11 at 37°C Metal ions Mn2+ and Co2+ increased activity by twofold, while Cu2+ and Fe2+ reduced activity by fivefold as compared to the control At 60°C and pH 6, the K m for oat-spelt xylan was 223 mg ml−1 and V max was 2968 IU mg−1 protein In the enzymatic prebleaching of eucalyptus Kraft pulp, the release of chromophores, formation of reducing sugars and brightness was higher while the Kappa number was lower than the control with increased enzyme dosage at 30% reduction of the original chlorine dioxide usage The thermostability, alkali-tolerance, negligible presence of cellulolytic activity, ability to improve brightness and capacity to reduce chlorine dioxide usage demonstrates the high potential of the enzyme for application in the biobleaching of Kraft pulp