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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
Yun-Jin Park1, Su-Yeon Kang1, Jinwon Lee, Sung-Yong Hong1, Seung Wook Kim1 
TL;DR: Under the optimized conditions, the activity and productivity of xylanase obtained after 5 days of fermentation were 5,071 IU/g of rice straw and 14,790 IU l–1 h–1, respectively.
Abstract: The initial moisture content, cultivation time, inoculum size and concentration of basal medium were optimized in solid state fermentation (SSF) for the production of xylanase by an Aspergillus niger mutant using statistical experimental designs. The cultivation time and concentration of basal medium were the most important factors affecting xylanase activity. An inoculum size of 5 x 10(5) spores/g, initial moisture content of 65%, cultivation time of 5 days and 10 times concentration of basal medium containing 50 times concentration of corn steep liquor were optimum for xylanase production in SSF. Under the optimized conditions, the activity and productivity of xylanase obtained after 5 days of fermentation were 5,071 IU/g of rice straw and 14,790 IU l(-1) h(-1), respectively. The xylanase activity predicted by a polynomial model was 5,484 IU/g of rice straw.

222 citations

Journal ArticleDOI
TL;DR: The ability of a cellulase preparation to hydrolyze pretreated softwood showed little correlation with its activity on filter paper, carboxymethylcellulose and Avicel; however, there was a significant correlation with the level of endogenous β-glucosidase and xylanase activity.

221 citations

Journal ArticleDOI
TL;DR: The characterization of these enzymes will be described along with comparisons to some newly described TS enzymes, which have advantages in new areas such as cyclodextrin production.
Abstract: The variety of thermostable (TS) enzymes has been steadily increasing for use in industrial applications, mainly as replacements for thermolabile (TL) enzymes. For example, TS amylases fromBacillus licheniformis andBacillus stearothermophilus have replaced TL amylases fromBacillus subtilis. TS enzymes also have advantages in new areas such as cyclodextrin production. The TS cyclodextrin glycosyl transferase (CGTase) fromThermoanaerobacter sp. (95°C optimum) gives a higher productivity than the CGTase fromBacillus macerans (55°C optimum). In the area of enzymatic bleach boosting of wood pulps, a TS xylanase (Myceliophera thermophila) would be advantageous over a TL xylanase (Trichoderma reesei), due to the high temperature of the incoming pulp. Not all TS enzymes are from thermophiles; the mesophileCandida antarctica produces a TS lipase which has a temperature optimum of 90°C when immobilized. The characterization of these enzymes will be described along with comparisons to some newly described TS enzymes.

220 citations

Journal ArticleDOI
TL;DR: This key finding elucidates a possible mechanism for cellulase inhibition by xylan and xylo-oligomers and emphasizes the need to optimize the enzyme formulation for each pretreated substrate.
Abstract: Background Hemicellulose is often credited with being one of the important physical barriers to enzymatic hydrolysis of cellulose, and acts by blocking enzyme access to the cellulose surface. In addition, our recent research has suggested that hemicelluloses, particularly in the form of xylan and its oligomers, can more strongly inhibit cellulase activity than do glucose and cellobiose. Removal of hemicelluloses or elimination of their negative effects can therefore become especially pivotal to achieving higher cellulose conversion with lower enzyme doses.

217 citations

Journal ArticleDOI
TL;DR: In this paper, dilute alkaline (NaOH) pretreatment followed by enzyme saccharification of wheat straw to produce fermentable sugars was used to evaluate the impacts of varying pretreatment parameters on enzymatic digestion of residual solid materials.
Abstract: Physico-chemical pretreatment of lignocellulosic biomass is critical in removing substrate-specific barriers to cellulolytic enzyme attack. Alkaline pretreatment successfully delignifies biomass by disrupting the ester bonds cross-linking lignin and xylan, resulting in cellulose and hemicellulose enriched fractions. Here we report the use of dilute alkaline (NaOH) pretreatment followed by enzyme saccharifications of wheat straw to produce fermentable sugars. Specifically, we have assessed the impacts of varying pretreatment parameters (temperature, time and alkalinity) on enzymatic digestion of residual solid materials. Following pretreatment, recoverable solids and lignin contents were found to be inversely proportional to the severity of the pretreatment process. Elevating temperature and alkaline strengths maximised hemicellulose and lignin solubilisation and enhanced enzymatic saccharifications. Pretreating wheat straw with 2% NaOH for 30 min at 121 °C improved enzyme saccharification 6.3-fold when compared to control samples. Similarly, a 4.9-fold increase in total sugar yields from samples treated with 2% NaOH at 60 °C for 90min, confirmed the importance of alkali inclusion. A combination of three commercial enzyme preparations (cellulase, β-glucosidase and xylanase) was found to maximise monomeric sugar release, particularly for substrates with higher xylan contents. In essence, the combined enzyme activities increased total sugar release 1.65-fold and effectively reduced cellulase enzyme loadings 3-fold. Prehydrolysate liquors contained 4-fold more total phenolics compared to enzyme saccharification mixtures. Harsher pretreatment conditions provide saccharified hydrolysates with reduced phenolic content and greater fermentation potential.

216 citations


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