Xu Lin, Wang Lian, Zhou Xue-Rong, Chen Wen-Chao, Singh Surinder, Hu Zhe, Huang Feng-Hong, Wan Xia
1Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan, 430062 People's Republic of China.
2CSIRO Agriculture & Food, Canberra, 2601 Australia.
Biotechnol Biofuels. 2018 Jun 25;11:177. doi: 10.1186/s13068-018-1177-x. eCollection 2018.
Triacylglycerols (TAGs) rich in medium-chain fatty acids (MCFAs, C10-14 fatty acids) are valuable feedstocks for biofuels and chemicals. Natural sources of TAGs rich in MCFAs are restricted to a limited number of plant species, which are unsuitable for mass agronomic production. Instead, the modification of seed or non-seed tissue oils to increase MCFA content has been investigated. In addition, microbial oils are considered as promising sustainable feedstocks for providing TAGs, although little has been done to tailor the fatty acids in microbial TAGs.
Here, we first assessed various wax synthase/acyl-coenzyme A:diacylglycerol acyltransferases, phosphatidic acid phosphatases, acyl-CoA synthetases as well as putative fatty acid metabolism regulators for producing high levels of TAGs in . Activation of endogenous free fatty acids with tailored chain length via overexpression of the castor thioesterase RcFatB and the subsequent incorporation of such fatty acids into glycerol backbones shifted the TAG profile in the desired way. Metabolic and nutrient optimization of the engineered bacterial cells resulted in greatly elevated TAG levels (399.4 mg/L) with 43.8% MCFAs, representing the highest TAG levels in under shake flask conditions. Engineered cells were observed to contain membrane-bound yet robust lipid droplets.
We introduced a complete Kennedy pathway into non-oleaginous . towards developing a bacterial platform for the sustainable production of TAGs rich in MCFAs. Strategies reported here illustrate the possibility of prokaryotic cell factories for the efficient production of TAGs rich in MCFAs.
富含中链脂肪酸（MCFAs，C10 - 14脂肪酸）的三酰甘油（TAGs）是生物燃料和化学品的宝贵原料。富含MCFAs的TAGs的天然来源仅限于少数植物物种，这些物种不适合大规模农艺生产。相反，人们已经研究了对种子或非种子组织油进行改性以增加MCFA含量。此外，微生物油被认为是提供TAGs的有前景的可持续原料，尽管在调整微生物TAGs中的脂肪酸方面做得很少。
在这里，我们首先评估了各种蜡合酶/酰基辅酶A：二酰甘油酰基转移酶、磷脂酸磷酸酶、酰基辅酶A合成酶以及假定的脂肪酸代谢调节剂，以便在[具体生物名称未给出]中产生高水平的TAGs。通过蓖麻硫酯酶RcFatB的过表达激活具有特定链长的内源性游离脂肪酸，并随后将这些脂肪酸掺入甘油骨架中，以期望的方式改变了TAG谱。对工程化细菌细胞的代谢和营养进行优化，使得TAG水平大幅提高（399.4 mg/L），其中MCFAs含量为43.8%，这代表了摇瓶条件下[具体生物名称未给出]中的最高TAG水平。观察到工程化细胞含有膜结合但稳定的脂滴。
我们将完整的肯尼迪途径引入非油质的[具体生物名称未给出]，朝着开发一个用于可持续生产富含MCFAs的TAGs的细菌平台迈进。这里报道的策略说明了原核细胞工厂高效生产富含MCFAs的TAGs的可能性。
