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Xylanase

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


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Journal ArticleDOI
TL;DR: An experimental design was used to determine the optimal composition of a Trichoderma reesei enzyme mixture, comprising the main cellulase and hemicellulase activities, for the hydrolysis of steam-exploded wheat straw and the developed model could reliably predict hydrolytic yields of enzyme mixtures in the studied domain.
Abstract: An efficient hydrolysis of lignocellulosic substrates to soluble sugars for biofuel production necessitates the interplay and synergistic interaction of multiple enzymes. An optimized enzyme mixture is crucial for reduced cost of the enzymatic hydrolysis step in a bioethanol production process and its composition will depend on the substrate and type of pretreatment used. In the present study, an experimental design was used to determine the optimal composition of a Trichoderma reesei enzyme mixture, comprising the main cellulase and hemicellulase activities, for the hydrolysis of steam-exploded wheat straw. Six enzymes, CBH1 (Cel7a), CBH2 (Cel6a), EG1 (Cel7b), EG2 (Cel5a), as well as the xyloglucanase Cel74a and the xylanase XYN1 (Xyl11a) were purified from a T. reesei culture under lactose/xylose-induced conditions. Sugar release was followed in milliliter-scale hydrolysis assays for 48 hours and the influence of the mixture on initial conversion rates and final yields is assessed. The developed model could show that both responses were strongly correlated. Model predictions suggest that optimal hydrolysis yields can be obtained over a wide range of CBH1 to CBH2 ratios, but necessitates a high proportion of EG1 (13% to 25%) which cannot be replaced by EG2. Whereas 5% to 10% of the latter enzyme and a xylanase content above 6% are required for highest yields, these enzymes are predicted to be less important in the initial stage of hydrolysis. The developed model could reliably predict hydrolysis yields of enzyme mixtures in the studied domain and highlighted the importance of the respective enzyme components in both the initial and the final hydrolysis phase of steam-exploded wheat straw.

78 citations

Journal ArticleDOI
TL;DR: Thermomyces lanuginosus, isolated from self-heated jute stacks in Bangladesh, was studied for production of high level of cellulase-free thermostable xylanase at 50°C using xylan and the enzyme was almost stable over a broad range of pH 3–9 at 20°C.

78 citations

Journal ArticleDOI
TL;DR: By screening for mutants which could not degrade cellulose, several cellulase-less mutants were isolated from the wood-rotting fungus Polyporus adustus and it is proposed that this group of enzymes is under the control of a single common regulator gene.
Abstract: By screening for mutants which could not degrade cellulose, several cellulase-less mutants were isolated from the wood-rotting fungus Polyporus adustus. Most of the mutants lacked mannanase and xylanase as well. In wild type, the level of cellulase, mannanase, and xylanase was higher when the fungus was grown in a medium containing cellulose than in a medium lacking cellulose. It is proposed that in P. adustus, the induction of this group of enzymes is under the control of a single common regulator gene.

78 citations

Journal ArticleDOI
TL;DR: Antisera raised against either the denatured 22- or 14-kilodalton (kDa) polypeptides comprising the native protein were ineffective in precipitating either activity.
Abstract: A protein component of Cellulysin is known to induce ethylene biosynthesis in a variety of plant tissues and harbors an endo-beta-1,4-xylanase activity. Antiserum to the native ethylene biosynthesis-inducing xylanase immunoprecipitates both the enzymatic and biological activities. However, antisera raised against either the denatured 22- or 14-kilodalton (kDa) polypeptides comprising the native protein were ineffective in precipitating either activity. All three antibodies recognized the 14- and 22-kDa antigens on immunoblots. Synthesis of a single 22-kDa extracellular polypeptide detectable on immunoblots with the three antisera against the Cellulysin polypeptides was inducible in Trichoderma viride during growth on D-xylose, xylan, or crude cell-wall preparations. Induction was not observed when the fungus was grown on L-xylose, beta-methyl-D-xylose, glucose, or several purified cell-wall polymers, including pectin, polygalacturonate, arabinogalactan, and cellulose. Production of this protein was influenced by substrate concentration and culture pH. When grown in the induction medium, several other species of Trichoderma and Gliocladium also synthesize a 22-kDa xylanase that could be detected on immunoblots and was capable of inducing ethylene biosynthesis. Isoelectric focusing demonstrated that the cross-reactive polypeptides from these fungi exist as isoforms. The primary form had a pI of 9.4, and less abundant forms focused at pI 8.4 and lower. Culture filtrates of two plant pathogens, Fusarium oxysporum f. sp. pisi and Macrophomina phaseolina, also contained ethylene biosynthesis-inducing and xylanase activities, as well as a 22-kDa cross-reactive polypeptide. M. phaseolina filtrates also contained substantial amounts of a 14-kDa polypeptide similar to that found in Cellulysin

78 citations

Journal ArticleDOI
TL;DR: Bacillus thermoalkalophilus isolated from termite-infested mound soils of the semi-arid zones of India had the ability to produce good amounts of xylanase(s) from cheap agricultural wastes, and of the two hemicellulosic substrates tested, bagasse was found to be the better inducer for xylan enzyme production.
Abstract: Bacillus thermoalkalophilus isolated from termite-infested mound soils of the semi-arid zones of India had the ability to produce good amounts of xylanase(s) from cheap agricultural wastes. Of the two hemicellulosic substrates tested, bagasse was found to be the better inducer for xylanase production. Alkali treatment of bagasse and rice husk had varied effects on enzyme production. The enzyme preparation had activity optima at 60° C and 70° C and a half-life of 60 min at 65° C. The enzyme was stable for 24 h over a pH range of 4.0–6.0, while maximum activity was observed at pH 6.0–7.0. Enzyme production and activity were inhibited by the end-product of xylan hydrolysis, xylose.

78 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023199
2022463
2021254
2020289
2019278
2018303