College of Marine Life Sciences, Ocean university of China, Yushan Road, No. 5, Qingdao, China.
College of Marine Life Sciences, Ocean university of China, Yushan Road, No. 5, Qingdao, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, 266003 Qingdao, China.
Int J Biol Macromol. 2019 Dec 1;141:268-277. doi: 10.1016/j.ijbiomac.2019.08.264. Epub 2019 Sep 2.
Aureobasidium melanogenum TN3-1 isolated from a natural honey was a highly genome-duplicated yeast-like fungal strain and a very high pullulan producer. In this study, simultaneous removal of both duplicated AMY1 genes encoding α-amylase and duplicated PKS1 genes responsible for melanin biosynthesis in A. melanogenum TN3-1 rendered a mutant AMY-PKS-11 to transform 140.0 g/L of glucose to produce 103.50 g/L of pigment-free pullulan with molecular weight (Mw) of 3.2 × 10 g/mol. α-Amylase activity produced by the mutant AMY-PKS-11 and expression of the AMY1 genes and PKS genes in it was reduced, but expression of various genes responsible for pullulan biosynthesis in the mutant AMY-PKS-11 was up-regulated. The produced pullulan was used to make the capsule shells successfully and the prepared pullulan capsule shells had various advantages such as high strength, good oxygen barrier properties, raw materials availability, tightness, lightness and high water resistance and may be suitable for all the consumers. Therefore, the prepared capsule shells had highly potential applications in food and pharmaceutical industries.
从天然蜂蜜中分离出的嗜热丝孢酵母 TN3-1 是一株高度基因组重复的酵母样真菌菌株，也是一种非常高产普鲁兰的菌株。在本研究中，同时敲除嗜热丝孢酵母 TN3-1 中编码α-淀粉酶的两个重复 AMY1 基因和负责黑色素生物合成的两个重复 PKS1 基因，得到一个突变株 AMY-PKS-11，该突变株可将 140.0 g/L 的葡萄糖转化为 103.50 g/L 的无色素普鲁兰，其分子量（Mw）为 3.2×10 g/mol。突变株 AMY-PKS-11 产生的α-淀粉酶活性和 AMY1 基因及 PKS 基因的表达降低，但突变株中各种负责普鲁兰生物合成的基因表达上调。所产生的普鲁兰成功地用于制造胶囊壳，制备的普鲁兰胶囊壳具有高强度、良好的氧气阻隔性能、原料可用性、密封性、轻便性和高耐水性等优点，可能适合所有消费者。因此，所制备的胶囊壳在食品和制药工业中有很高的应用潜力。
