Suyama Akiko, Higuchi Yujiro, Urushihara Masahiro, Maeda Yuka, Takegawa Kaoru
Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581, Japan.
Research Center, Asahi Glass Co., Ltd., 1150 Hazawacho, Yokohama 221-8755, Japan.
J Biosci Bioeng. 2017 Oct;124(4):392-399. doi: 10.1016/j.jbiosc.2017.04.015. Epub 2017 May 15.
3-Hydroxypropionic acid (3-HP) can be converted into derivatives such as acrylic acid, a source for producing super absorbent polymers. Although Escherichia coli has often been used for 3-HP production, it exhibits low tolerance to 3-HP. To circumvent this problem, we selected the fission yeast Schizosaccharomyces pombe as this microorganism has higher tolerance to 3-HP than E. coli. Therefore, we constructed S. pombe transformants overexpressing two genes, one encoding the S. pombe acetyl-CoA carboxylase (Cut6p) and the other encoding the malonyl-CoA reductase derived from Chloroflexus aurantiacus (CaMCR). To prevent the degradation of these expressed proteins, we employed an S. pombe protease-deficient strain. Moreover, to increase the cytosolic concentration of acetyl-CoA, we supplemented acetate to the medium, which improved 3-HP production. To further produce 3-HP by overexpressing Cut6p and CaMCR, we exploited the highly expressing S. pombe hsp9 promoter. Finally, culturing in high-density reached 3-HP production to 7.6 g/L at 31 h.
3-羟基丙酸（3-HP）可转化为丙烯酸等衍生物，丙烯酸是生产高吸水性聚合物的原料。尽管大肠杆菌常被用于生产3-HP，但它对3-HP的耐受性较低。为解决这一问题，我们选择了裂殖酵母粟酒裂殖酵母，因为这种微生物对3-HP的耐受性比大肠杆菌更高。因此，我们构建了粟酒裂殖酵母转化体，使其过表达两个基因，一个编码粟酒裂殖酵母乙酰辅酶A羧化酶（Cut6p），另一个编码源自橙黄嗜热栖热菌的丙二酰辅酶A还原酶（CaMCR）。为防止这些表达蛋白的降解，我们使用了粟酒裂殖酵母蛋白酶缺陷型菌株。此外，为提高乙酰辅酶A的胞质浓度，我们在培养基中添加了乙酸盐，这提高了3-HP的产量。为通过过表达Cut6p和CaMCR进一步生产3-HP，我们利用了高表达的粟酒裂殖酵母hsp9启动子。最后，高密度培养在31小时时使3-HP产量达到7.6 g/L。
