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首页> 外文期刊>Applied Microbiology and Biotechnology >Mode of depolymerisation of hemicellulose by various mannanases and xylanases in relation to their ability to bleach softwood pulp
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Mode of depolymerisation of hemicellulose by various mannanases and xylanases in relation to their ability to bleach softwood pulp

机译：各种甘露聚糖酶和木聚糖酶使半纤维素解聚的方式与漂白软木纸浆的能力有关

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摘要

Endo-mannanases and endo-xylanases cleave different heteromannans and xylans yielding mainly dimers and trimers of the corresponding sugars as end-products. However, in the early stages of hydrolysis, four purified mannanases and four xylanases from fungal and bacterial origin, examined in this study, showed a different pattern of released oligomers (determined up to the pentamers). Furthermore, some of these enzymes showed a preference for cleaving the polysaccharides in the middle of the chain while others acted more at the end. When the increase in the specific fluidity of mannan and xylan solutions per reducing sugar released (K-v) was measured against the bleaching effect of the enzymes on softwood kraft pulp, a correlation was found. A xylanase from Penicillium simplicissimum (K-v = O.15 1 mPa(-1)s(-1)g(-1)) and a mannanase from Sclerotium rolfsii (K-v = 0.12 1 mPa(-1)s(-1)g(-1)) applied in a O(QX)P bleaching sequence (O = oxygen delignification, X = treatment with hemicellulolytic enzymes, Q = chelation of metals, P = treatment with hydrogen peroxide in alkaline solution) gave a high brightness increase of 3.0% and 1.9% ISO respectively. A less significant brightness increase was obtained with enzymes showing lower K-v values, such as a xylanase from Schizophyllum commune (K-v = 0.051 1 mPa(-1)s(-1)g(-1),0.2% ISO) and a bacterial mannanase (K-v = 0.061 1 mPa(-1)s(-1)g(-1),0.5% ISO).
机译：内甘露聚糖酶和内木聚糖酶裂解不同的杂甘露聚糖和木聚糖，主要产生相应糖的二聚体和三聚体作为终产物。但是，在水解的早期阶段，在这项研究中检查了来自真菌和细菌的四种纯化的甘露聚糖酶和四种木聚糖酶，显示出不同的释放低聚物模式（取决于五聚体）。此外，这些酶中的某些显示出优先裂解链中部的多糖，而其他酶则在末端发挥更多作用。当测定每释放的还原糖（K-v）中甘露聚糖和木聚糖溶液的比流动性的增加与酶对软木牛皮纸浆的漂白作用的关系时，发现了相关性。来自简单青霉的木聚糖酶（Kv = O.15 1 mPa（-1）s（-1）g（-1））和来自Sclerotium rolfsii的甘露聚糖酶（Kv = 0.12 1 mPa（-1）s（-1）g （-1））以O（QX）P漂白顺序应用（O =氧脱木素，X =半纤维素分解酶处理，Q =金属螯合，P =在碱性溶液中用过氧化氢处理）产生高亮度ISO分别为3.0％和1.9％。用显示较低Kv值的酶获得较低的亮度增加，例如来自裂殖酵母的木聚糖酶（Kv = 0.051 1 mPa（-1）s（-1）g（-1），0.2％ISO）和细菌甘露聚糖酶（Kv = 0.061 1 mPa（-1）s（-1）g（-1），0.5％ISO）。

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