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首页> 外文期刊>Food microbiology >Identification and characterization of a glucan-producing enzyme from Lactobacillus hilgardii TMW 1.828 involved in granule formation of water kefir
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Identification and characterization of a glucan-producing enzyme from Lactobacillus hilgardii TMW 1.828 involved in granule formation of water kefir

机译：希尔加德乳杆菌TMW 1.828中参与水开菲尔颗粒形成的葡聚糖生产酶的鉴定和表征

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摘要

Water kefir is a home made fermented beverage based on a sucrose solution with fruit extracts. The inoculum of such fermentations consists of macroscopic granula containing lactic and acetic acid bacteria, and yeasts, which are embedded in an exopolysaccharide (EPS) matrix. In this work, a strain of Lactobacillus hilgardii producing large amounts of the granule-forming dextran could be isolated. The glycosyltransferans (Gtf) commonly called glucansucrase responsible for the production of this dextran was purified from L. hilgardii. Characteristic enzyme kinetic data were obtained. Optimum activity was observed between pH 4.3 and 4.6 and temperatures between 40℃ and 45℃. A Michaelis-Menten kinetic could be fit to the experimental data and a K_M of 0.0385 M was calculated. The corresponding gtf gene was identified and characterized. It encodes a 1448 amino acid protein with higher homologies to Gtfs of Lactobacillus parabuchneri, Lactobacillus sakei and Lactobacillus fermentum followed by lower homologies to Lactobacillus reuteri Gtfs. By knockout experiments the role of this gene in granule dextran production was demonstrated.
机译：开菲尔酒是一种基于蔗糖溶液和水果提取物的自制发酵饮料。此类发酵的接种物由包含乳酸菌和乙酸菌的宏观颗粒以及嵌入在胞外多糖（EPS）基质中的酵母组成。在这项工作中，可以分离出产生大量形成颗粒的葡聚糖的希尔氏乳杆菌菌株。负责产生这种右旋糖酐的糖基转移酶（Gtf）通常被称为葡聚糖蔗糖酶，是从希尔氏乳杆菌中纯化得到的。获得了特征酶动力学数据。在pH 4.3和4.6之间以及温度在40℃和45℃之间观察到最佳活性。 Michaelis-Menten动力学可以拟合实验数据，计算出的K_M为0.0385M。鉴定并鉴定了相应的gtf基因。它编码1448个氨基酸蛋白，与副乳杆菌，清酒乳杆菌和发酵乳杆菌的Gtf具有较高的同源性，随后与罗伊氏乳杆菌的Gtfs具有较低的同源性。通过敲除实验证明了该基因在葡聚糖颗粒生产中的作用。

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