Tomita Yuko, Yoshioka Kazumasa, Iijima Hiroko, Nakashima Ayaka, Iwata Osamu, Suzuki Kengo, Hasunuma Tomohisa, Kondo Akihiko, Hirai Masami Yokota, Osanai Takashi
School of Agriculture, Meiji University Kawasaki, Japan.
euglena Co., Ltd Tokyo, Japan.
Front Microbiol. 2016 Dec 21;7:2050. doi: 10.3389/fmicb.2016.02050. eCollection 2016.
is a eukaryotic, unicellular phytoflagellate that has been widely studied in basic science and applied science. Under dark, anaerobic conditions, the cells of produce a wax ester that can be converted into biofuel. Here, we demonstrate that under dark, anaerobic conditions, excretes organic acids, such as succinate and lactate, which are bulk chemicals used in the production of bioplastics. The levels of succinate were altered by changes in the medium and temperature during dark, anaerobic incubation. Succinate production was enhanced when cells were incubated in CM medium in the presence of NaHCO. Excretion of lactate was minimal in the absence of external carbon sources, but lactate was produced in the presence of glucose during dark, anaerobic incubation. predominantly produced L-lactate; however, the percentage of D-lactate increased to 28.4% in CM medium at 30°C. Finally, we used a commercial strain of for succinate production and found that nitrogen-starved cells, incubated under dark, anaerobic conditions, produced 869.6 mg/L succinate over a 3-day incubation period, which was 70-fold higher than the amount produced by nitrogen-replete cells. This is the first study to demonstrate organic acid excretion by cells and to reveal novel aspects of primary carbon metabolism in this organism.
是一种真核单细胞植物鞭毛虫，在基础科学和应用科学领域都得到了广泛研究。在黑暗、厌氧条件下，该细胞会产生一种蜡酯，这种蜡酯可转化为生物燃料。在此，我们证明在黑暗、厌氧条件下，会分泌琥珀酸和乳酸等有机酸，这些都是用于生产生物塑料的大宗化学品。在黑暗厌氧培养过程中，培养基和温度的变化会改变琥珀酸的水平。当细胞在含有NaHCO的CM培养基中培养时，琥珀酸产量会增加。在没有外部碳源的情况下，乳酸分泌极少，但在黑暗厌氧培养过程中，有葡萄糖存在时会产生乳酸。主要产生L-乳酸；然而，在30°C的CM培养基中，D-乳酸的比例增加到了28.4%。最后，我们使用一种商业菌株进行琥珀酸生产，发现在黑暗、厌氧条件下培养的缺氮细胞，在3天的培养期内产生了869.6 mg/L的琥珀酸，这比富氮细胞产生的量高70倍。这是首次证明细胞分泌有机酸并揭示该生物体初级碳代谢新方面的研究。
