National Key Laboratory of Wheat and Maize Crop Science, Henan Agricultural University, Zhengzhou 450002, China.
College of Life Sciences, Henan Agricultural University, Zhengzhou 450002, China.
Int J Mol Sci. 2023 Feb 15;24(4):3927. doi: 10.3390/ijms24043927.
Maize accumulates large amounts of starch in seeds which have been used as food for human and animals. Maize starch is an importantly industrial raw material for bioethanol production. One critical step in bioethanol production is degrading starch to oligosaccharides and glucose by α-amylase and glucoamylase. This step usually requires high temperature and additional equipment, leading to an increased production cost. Currently, there remains a lack of specially designed maize cultivars with optimized starch (amylose and amylopectin) compositions for bioethanol production. We discussed the features of starch granules suitable for efficient enzymatic digestion. Thus far, great advances have been made in molecular characterization of the key proteins involved in starch metabolism in maize seeds. The review explores how these proteins affect starch metabolism pathway, especially in controlling the composition, size and features of starch. We highlight the roles of key enzymes in controlling amylose/amylopectin ratio and granules architecture. Based on current technological process of bioethanol production using maize starch, we propose that several key enzymes can be modified in abundance or activities via genetic engineering to synthesize easily degraded starch granules in maize seeds. The review provides a clue for developing special maize cultivars as raw material in the bioethanol industry.
玉米在种子中积累大量淀粉，这些淀粉曾被用作人类和动物的食物。玉米淀粉是生产生物乙醇的重要工业原料。生物乙醇生产的一个关键步骤是通过α-淀粉酶和糖化酶将淀粉降解为寡糖和葡萄糖。这一步骤通常需要高温和额外的设备，导致生产成本增加。目前，仍然缺乏专门设计的玉米品种，其淀粉（直链淀粉和支链淀粉）组成适合生物乙醇生产。我们讨论了适合高效酶解的淀粉颗粒的特征。迄今为止，在玉米种子淀粉代谢关键蛋白的分子特征方面已经取得了很大进展。综述探讨了这些蛋白如何影响淀粉代谢途径，特别是在控制淀粉的组成、大小和特征方面。我们强调了关键酶在控制直链淀粉/支链淀粉比例和颗粒结构中的作用。基于目前使用玉米淀粉生产生物乙醇的工艺，我们提出可以通过遗传工程大量或改变关键酶的活性，在玉米种子中合成易于降解的淀粉颗粒。该综述为开发特殊的玉米品种作为生物乙醇工业的原料提供了线索。
