Laboratory of Cyanobacterial Biotechnology, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
Microbial Chemistry, Department of Chemistry-Ångström, Uppsala University, Box 523, SE-75120 Uppsala, Sweden.
Int J Mol Sci. 2021 Oct 25;22(21):11468. doi: 10.3390/ijms222111468.
Although engineered cyanobacteria for the production of lipids and fatty acids (FAs) are intelligently used as sustainable biofuel resources, intracellularly overproduced FAs disturb cellular homeostasis and eventually generate lethal toxicity. In order to improve their production by enhancing FFAs secretion into a medium, we constructed three engineered 6803 strains including KA (a mutant lacking the gene), KAOL (KA overexpressing , encoding lipase A in membrane lipid hydrolysis), and KAOGR (KA overexpressing quadruple /, related to the CBB cycle). Certain contents of intracellular lipids and secreted FFAs of all engineered strains were higher than those of the wild type. Remarkably, the KAOL strain attained the highest level of secreted FFAs by about 21.9%w/DCW at day 5 of normal BG cultivation, with a higher growth rate and shorter doubling time. TEM images provided crucial evidence on the morphological changes of the KAOL strain, which accumulated abundant droplets on regions of thylakoid membranes throughout the cell when compared with wild type. On the other hand, BG-N condition significantly induced contents of both intracellular lipids and secreted FFAs of the KAOL strain up to 37.2 and 24.5%w/DCW, respectively, within 5 days. Then, for the first time, we shone a spotlight onto the overexpression of in the mutant of as another potential strategy to achieve higher FFAs secretion with sustainable growth.
尽管工程化蓝藻被智能地用于生产脂质和脂肪酸 (FAs) 以作为可持续的生物燃料资源，但细胞内过量产生的 FAs 会干扰细胞内稳态，最终产生致命毒性。为了通过增强 FA 向培养基中的分泌来提高它们的产量，我们构建了三种工程化的 6803 菌株，包括 KA（缺失 基因的突变体）、KAOL（过量表达 ，编码膜脂水解中的脂肪酶 A）和 KAOGR（过量表达四重 ，与 CBB 循环有关）。所有工程菌株的细胞内脂质和分泌的游离脂肪酸的某些含量都高于野生型。值得注意的是，KAOL 菌株在正常 BG 培养的第 5 天达到了约 21.9%w/DCW 的最高分泌游离脂肪酸水平，具有更高的生长速度和更短的倍增时间。TEM 图像为 KAOL 菌株的形态变化提供了关键证据，与野生型相比，该菌株在类囊体膜的区域积累了丰富的液滴。另一方面，BG-N 条件在 5 天内分别将 KAOL 菌株的细胞内脂质和分泌的游离脂肪酸含量显著提高到 37.2%w/DCW 和 24.5%w/DCW。然后，我们首次关注到 在 突变体中的过表达可以作为实现更高游离脂肪酸分泌和可持续生长的另一种潜在策略。
