Department of Chemistry and Bioengineering, Tampere University of Technology, Finland.
Microb Cell Fact. 2011 May 18;10:36. doi: 10.1186/1475-2859-10-36.
Triacylglycerols are used in various purposes including food applications, cosmetics, oleochemicals and biofuels. Currently the main sources for triacylglycerol are vegetable oils, and microbial triacylglycerol has been suggested as an alternative for these. Due to the low production rates and yields of microbial processes, the role of metabolic engineering has become more significant. As a robust model organism for genetic and metabolic studies, and for the natural capability to produce triacylglycerol, Acinetobacter baylyi ADP1 serves as an excellent organism for modelling the effects of metabolic engineering for energy molecule biosynthesis.
Beneficial gene deletions regarding triacylglycerol production were screened by computational means exploiting the metabolic model of ADP1. Four deletions, acr1, poxB, dgkA, and a triacylglycerol lipase were chosen to be studied experimentally both separately and concurrently by constructing a knock-out strain (MT) with three of the deletions. Improvements in triacylglycerol production were observed: the strain MT produced 5.6 fold more triacylglycerol (mg/g cell dry weight) compared to the wild type strain, and the proportion of triacylglycerol in total lipids was increased by 8-fold.
In silico predictions of beneficial gene deletions were verified experimentally. The chosen single and multiple gene deletions affected beneficially the natural triacylglycerol metabolism of A. baylyi ADP1. This study demonstrates the importance of single gene deletions in triacylglycerol metabolism, and proposes Acinetobacter sp. ADP1 as a model system for bioenergetic studies regarding metabolic engineering.
甘油三酯在食品应用、化妆品、油脂化学和生物燃料等各种用途中都有使用。目前，甘油三酯的主要来源是植物油，微生物甘油三酯已被提议作为替代物。由于微生物过程的产率和产量较低，代谢工程的作用变得更加重要。作为遗传和代谢研究的稳健模式生物，以及自然产生甘油三酯的能力，不动杆菌属 ADP1 是模拟代谢工程对能源分子生物合成影响的优秀模型生物。
通过利用 ADP1 的代谢模型进行计算手段，筛选出了与甘油三酯生产有关的有益基因缺失。选择了四个缺失，即 acr1、poxB、dgkA 和一种甘油三酯脂肪酶，通过构建一个具有三个缺失的敲除菌株 (MT) 进行单独和同时的实验研究。观察到甘油三酯产量的提高：与野生型菌株相比，MT 菌株产生的甘油三酯（mg/g 细胞干重）增加了 5.6 倍，总脂质中的甘油三酯比例增加了 8 倍。
有益基因缺失的计算机预测得到了实验验证。所选择的单个和多个基因缺失对 A. baylyi ADP1 的天然甘油三酯代谢产生了有益影响。本研究证明了单基因缺失在甘油三酯代谢中的重要性，并提出不动杆菌属 ADP1 作为代谢工程生物能源研究的模型系统。
