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首页> 外文学位 >Production of galacto-oligosaccharides from lactose by Aspergillus oryzae beta-galactosidase immobilized on cotton cloth.
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Production of galacto-oligosaccharides from lactose by Aspergillus oryzae beta-galactosidase immobilized on cotton cloth.

机译：通过固定在棉布上的米曲霉β-半乳糖苷酶从乳糖生产半乳糖低聚糖。

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Knitted cotton terry cloth as a novel and inexpensive fibrous matrix was evaluated for the development of fibrous bed biocatalyst reactor. Aspergillus oryzae β-galactosidase was immobilized on cotton cloth with two different methods. The first method used p-toluenesulfonyl chloride (tosyl) to activate cotton cloth and the enzyme was then coupled to the tosylated sites. Approximately 50 mg enzyme per gram of cloth was coupled with an immobilization yield of 55%. The second method involving polyethylenimine (PEI) relied on PEI-enzyme aggregate formation and coating of the aggregates on the fibrils of cotton cloth. Immobilized enzyme activity under optimized condition reached to 90–95% of free enzyme at a loading of 250 mg/g. Thermal stability of the immobilized enzymes were greatly increased, with tosyl immobilized enzyme showing 25-fold increase as compared with the free enzyme.; The production of galacto-oligosaccharides (GOS) from lactose was studied by cotton cloth immobilized enzyme by both methods. The total amounts and types of GOS produced were mainly affected by the initial lactose concentration in the reaction media. A maximum GOS production of 27% (w/w) was achieved at 50% lactose conversion with 500 g/L of initial lactose concentration. Trisaccharides were the major types of GOS formed, accounting for more than 70% of the total GOS produced in the reaction. Monosaccharides produced during lactose hydrolysis severely delayed GOS formation and decreased 10–15% in GOS content.; A stable long-term continuous operation was demonstrated with the cotton cloth immobilized enzyme reactor. Overall, the high porosity (>95%) and low-pressure drop of cotton cloth allowed the reactor to be operated without any difficulties. Even with high enzyme loadings, cotton cloth immobilized enzymes showed no reduction in GOS formation and did not impose any significant diffusion limitation. GOS productivities in the reactor were 106 g/L/h with tosyl activated cotton cloth immobilized enzyme and 5200 g/L/h with PEI immobilized enzyme, which is 100-fold higher than those reported in the literature. The cotton-cloth enzyme reactor thus can be used for economical production of GOS from lactose. GOS product can be used as a prebiotic food ingredient because of its many health benefits.
机译：评价了针织棉毛圈布作为一种新型且廉价的纤维基质，以开发纤维床生物催化剂反应器。用两种不同的方法将米曲霉β-半乳糖苷酶固定在棉布上。第一种方法使用 p -甲苯磺酰氯（tosyl）活化棉布，然后将酶偶联至甲苯磺酸化位点。每克布大约50 mg酶，固定率为55％。第二种涉及聚乙烯亚胺（PEI）的方法依赖于PEI酶聚集体的形成以及聚集体在棉布原纤维上的包覆。在优化条件下固定化酶活性达到250 mg / g负载量时游离酶的90–95％。固定化酶的热稳定性大大提高，与甲苯磺酰基固定化酶相比，游离酶的热稳定性提高了25倍。通过固定这两种方法的棉布固定酶研究了乳糖生产半乳糖低聚糖（GOS）的方法。产生的GOS的总量和类型主要受反应介质中初始乳糖浓度的影响。在初始乳糖浓度为500 g / L的情况下，乳糖转化率为50％时，最大GOS产量为27％（w / w）。三糖是形成的GOS的主要类型，占反应中产生的GOS总量的70％以上。乳糖水解过程中产生的单糖严重延迟了GOS的形成，并降低了10-15％的GOS含量。用棉布固定的酶反应器证实了稳定的长期连续操作。总体而言，高孔隙率（> 95％）和棉布的低压降使反应器可以轻松运行。即使具有高的酶负载量，固定化棉布的酶也没有降低GOS的形成，也没有施加任何明显的扩散限制。用甲苯磺酰基活化的棉布固定的酶，反应器中的GOS生产率为106 g / L / h，用PEI固定的酶，GOS生产率为5200 g / L / h，比文献报道的生产率高100倍。因此，棉布酶反应器可用于从乳糖经济地生产GOS。 GOS产品具有许多健康益处，因此可以用作益生元食品成分。

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