Engineered yeast whole-cell biocatalyst for direct degradation of alginate from macroalgae and production of non-commercialized useful monosaccharide from alginate
Engineered yeast whole-cell biocatalyst for direct degradation of alginate from macroalgae and production of non-commercialized useful monosaccharide from alginate
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DOI：
10.1007/s00253-015-7035-x
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发表时间：
2016-02-01
影响因子：
5
通讯作者：
Ueda, Mitsuyoshi
中科院分区：
文献类型：
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作者：
Takagi, Toshiyuki;Yokoi, Takahiro;Ueda, Mitsuyoshi
藻酸盐是褐藻的主要成分。在大型藻类中，内切海藻酸裂解酶首先将海藻酸降解为低聚糖。这些低聚糖被海藻酸裂解酶进一步分解成单糖。本研究分离了海藻酸同化海洋细菌Saccharphagus degradans的各种藻酸裂解酶基因，并利用酵母细胞表面展示系统展示了它们的酶。显示海藻酸内切酶活力的酵母菌有海藻酸裂解酶活性。另一方面，显示海藻酸7K的酵母具有海藻酸裂解酶的活性。在酵母细胞表面展示的ALG7A、ALG7D、ALG7K和ALG18J具有聚古龙酸裂解酶和聚甘露酸裂解酶活性。此外，与聚甘露糖酸相比，聚古龙酸更容易被ALG7A、ALG7K和ALG7D降解。相反，聚甘露糖酸比聚古龙酸更容易被阿尔法18J降解。我们进一步构建了共显示内切和外切海藻酸裂解酶的酵母。共展示酵母的降解率显著高于单一展示海藻酸裂解酶的酵母。ALG7A/ALG7K共展示酵母对藻酸盐的降解活性最高，反应60min，还原糖产量为1.98g/L。该系统和我们的研究结果一起，将有助于酿酒酵母从海藻酸盐中有效地利用和生产有用的和非商业化的单糖。
Alginate is a major component of brown macroalgae. In macroalgae, an endolytic alginate lyase first degrades alginate into oligosaccharides. These oligosaccharides are further broken down into monosaccharides by an exolytic alginate lyase. In this study, genes encoding various alginate lyases derived from alginate-assimilating marine bacterium Saccharophagus degradans were isolated, and their enzymes were displayed using the yeast cell surface display system. Alg7A-, Alg7D-, and Alg18J-displaying yeasts showed endolytic alginate lyase activity. On the other hand, Alg7K-displaying yeast showed exolytic alginate lyase activity. Alg7A, Alg7D, Alg7K, and Alg18J, when displayed on yeast cell surface, demonstrated both polyguluronate lyase and polymannuronate lyase activities. Additionally, polyguluronic acid could be much easily degraded by Alg7A, Alg7K, and Alg7D than polymannuronic acid. In contrast, polymannuronic acid could be much easily degraded by Alg18J than polyguluronic acid. We further constructed yeasts co-displaying endolytic and exolytic alginate lyases. Degradation efficiency by the co-displaying yeasts were significantly higher than single alginate lyase-displaying yeasts. Alg7A/Alg7K co-displaying yeast had maximum alginate-degrading activity, with production of 1.98 g/L of reducing sugars in a 60-min reaction. This system developed, along with our findings, will contribute to the efficient utilization and production of useful and non-commercialized monosaccharides from alginate by Saccharomyces cerevisiae.