Streptococcus infantarius 25124 isolated from pozol produces a high molecular weight amylopullulanase, a key enzyme for niche colonization
Streptococcus infantarius 25124 isolated from pozol produces a high molecular weight amylopullulanase, a key enzyme for niche colonization
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DOI：
10.1515/amylase-2021-0001
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发表时间：
2021-01
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影响因子：
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通讯作者：
Carolina Rodríguez-Saavedra;R. Rodríguez-Sanoja;D. Guillén;C. Wacher;G. Díaz-Ruiz
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文献类型：
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作者：
Carolina Rodríguez-Saavedra;R. Rodríguez-Sanoja;D. Guillén;C. Wacher;G. Díaz-Ruiz
摘要 Pozol 是一种用玉米面团制成的饮料，将玉米粒在石灰水中煮沸后制成，导致可溶性糖减少，淀粉是面团中主要的可发酵碳水化合物。此前，婴儿链球菌亚种。 fantarius 25124 (Sii-25124) 被鉴定为本产品中分离出的淀粉分解能力最强的细菌。对 Sii-25124 淀粉分解酶的分析揭示了两种淀粉酶，即 55.7 kDa 的细胞质 α-淀粉酶和 246.3 kDa 的细胞外淀粉支链淀粉酶，具有两个催化结构域，一个是典型的 α-淀粉酶，另一个是典型的支链淀粉酶/糖原脱支酶。使用 Sii-25124 细胞裂解物上清液对两种酶的联合活性进行表征，结果表明在 30°C 至 45°C 之间具有稳定性，pH 在 6.8 至 8.0 范围内具有稳定性。 Sii-25124 淀粉酶的联合活性显示，当使用淀粉作为底物时，还原糖的快速产生。相比之下，支链淀粉的还原糖产量较低，但在整个反应时间内稳步增加。 Sii-25124 产生的淀粉支链淀粉酶水解面团中的淀粉，产生低分子量寡糖，这些寡糖可能被转运到 Sii-25124 细胞中，以便细胞内的 α-淀粉酶将其水解为单糖和双糖。 Sii-25124 生产的淀粉支链淀粉酶可能是成功控制淀粉类食品发酵的专用酶的一个例子。
Abstract Pozol is a beverage made with maize dough that is prepared after boiling the kernels in limewater, causing a decrease in soluble sugars, with starch being the main fermentable carbohydrate in the dough. Previously, Streptococcus infantarius ssp. infantarius 25124 (Sii-25124) was identified as the most amylolytic bacteria isolated in this product. Analysis of Sii-25124 amylolytic enzymes revealed two amylases, a cytoplasmic α-amylase of 55.7 kDa and an extracellular amylopullulanase of 246.3 kDa, with two catalytic domains, one typical of an α-amylase and another typical of a pullulanase/glycogen debranching enzyme. Characterization of the joint activity of both enzymes using Sii-25124 cell lysate supernatant demonstrated stability between 30 °C and 45°C, and pH stability in a range between 6.8 and 8.0. The joint activity of Sii-25124 amylases showed a fast production of reducing sugars when starch was used as the substrate. In contrast, reducing sugar production from amylopectin was lower, but it steadily increased throughout the reaction time. The amylopullulanase produced by Sii-25124 hydrolyzes the starch in the dough to produce low molecular weight oligosaccharides, which may be transported into Sii-25124 cells, so that intracellular α-amylase hydrolyzes them to mono- and disaccharides. Amylopullulanase production by Sii-25124 could be an example of a specialized enzyme that successfully dominates starchy food fermentation.