In this study, Saccharomyces cerevisiae was genetically engineered to harbor the capability of utilizing celluloses for bioethanol production by displaying active cellulolytic enzymes on the cell surface. An endo‐1,4‐β‐glucanase gene egX was cloned from Bacillus pumilus C‐9 and its expression products, the EGX cellulases, were displayed on the cell surface of S. cerevisiae by fusing egX with aga2 that encodes the binding subunit of the S. cerevisiae cell wall protein α‐agglutinin. To achieve high gene copies and stability, multicopy integration was obtained by integrating the fusion aga2‐egX gene into the rDNA region of the S. cerevisiae chromosome. To achieve high expression and surface display efficiency, the aga2‐egX gene was expressed under the control of a strong promoter. The presence of the enzymatically active cellulase fusion proteins on the S. cerevisiae cell surface was verified by carboxymethyl cellulase activity assay and immunofluorescence microscopy. This work presented a promising strategy to genetically engineer yeasts to perform efficient fermentation of cellulosic materials for bioethanol production.

中文翻译：

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改进纤维素酶在酵母细胞表面的基因固定，用于使用纤维素生产生物乙醇

在这项研究中，酿酒酵母经过基因工程改造，通过在细胞表面展示活性纤维素分解酶，具有利用纤维素生产生物乙醇的能力。从短小芽孢杆菌 C-9 中克隆了一个内切 1,4-β-葡聚糖酶基因 egX，通过将 egX 与编码结合亚基的 aga2 融合，将其表达产物 EGX 纤维素酶展示在酿酒酵母的细胞表面。酿酒酵母细胞壁蛋白α-凝集素。为了实现高基因拷贝和稳定性，通过将融合 aga2-egX 基因整合到酿酒酵母染色体的 rDNA 区域中获得多拷贝整合。为了实现高表达和表面展示效率，aga2-egX 基因在强启动子的控制下表达。通过羧甲基纤维素酶活性测定和免疫荧光显微术验证了具有酶活性的纤维素酶融合蛋白在酿酒酵母细胞表面上的存在。这项工作提出了一种很有前景的策略，可以对酵母进行基因工程改造，以进行纤维素材料的高效发酵，以生产生物乙醇。