Mi Le, Qin Dandan, Cheng Jie, Wang Dan, Li Sha, Wei Xuetuan
School of Chemistry and Chemical Engineering, Chongqing University, Daxuecheng South Road 55, Shapingba District, Chongqing, 401331, People's Republic of China.
State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology, Nanjing, 210009, People's Republic of China.
J Ind Microbiol Biotechnol. 2017 Mar;44(3):419-430. doi: 10.1007/s10295-016-1888-6. Epub 2017 Jan 17.
Two engineered Escherichia coli strains, DQ101 (MG1655 fadD )/pDQTES and DQ101 (MG1655 fadD )/pDQTESZ were constructed to investigate the free fatty acid production using ionic liquid-based acid- or enzyme-catalyzed bamboo hydrolysate as carbon source in this study. The plasmid, pDQTES, carrying an acyl-ACP thioesterase 'TesA of E. coli in pTrc99A was constructed firstly, and then (3R)-hydroxyacyl-ACP dehydratase was ligated after the TesA to give the plasmid pDQTESZ. These two strains exhibited efficient fatty acid production when glucose was used as the sole carbon source, with a final concentration of 2.45 and 3.32 g/L, respectively. The free fatty acid production of the two strains on xylose is not as efficient as that on glucose, which was 2.32 and 2.96 g/L, respectively. For mixed sugars, DQ101 (MG1655 fadD )-based strains utilized glucose and pentose sequentially under the carbon catabolite repression (CCR) regulation. The highest total FFAs concentration from the mixed sugar culture reached 2.81 g/L by DQ101 (MG1655 fadD )/pDQTESZ. Furthermore, when ionic liquid-based enzyme-catalyzed bamboo hydrolysate was used as the carbon source, the strain DQ101 (MG1655 fadD )/pDQTESZ could produce 1.23 g/L FFAs with a yield of 0.13 g/g, and while it just produced 0.65 g/L free fatty acid with the ionic liquid-based acid-catalyzed bamboo hydrolysate as the feedstock. The results suggested that enzymatic catalyzed bamboo hydrolysate with ionic liquid pretreatment could serve as an efficient feedstock for free fatty acid production.
本研究构建了两株工程化大肠杆菌菌株DQ101 (MG1655 fadD )/pDQTES和DQ101 (MG1655 fadD )/pDQTESZ，以研究使用离子液体基酸催化或酶催化的竹水解物作为碳源生产游离脂肪酸。首先构建了携带大肠杆菌酰基-ACP硫酯酶“TesA”的质粒pDQTES，其位于pTrc99A中，然后在TesA之后连接(3R)-羟基酰基-ACP脱水酶，得到质粒pDQTESZ。当葡萄糖作为唯一碳源时，这两株菌株均表现出高效的脂肪酸生产能力，最终浓度分别为2.45 g/L和3.32 g/L。两株菌株在木糖上的游离脂肪酸产量不如在葡萄糖上高效，分别为2.32 g/L和2.96 g/L。对于混合糖，基于DQ101 (MG1655 fadD )的菌株在碳分解代谢物阻遏(CCR)调节下依次利用葡萄糖和戊糖。通过DQ101 (MG1655 fadD )/pDQTESZ从混合糖培养物中获得的最高总游离脂肪酸浓度达到2.81 g/L。此外，当使用离子液体基酶催化的竹水解物作为碳源时，菌株DQ101 (MG1655 fadD )/pDQTESZ能够产生1.23 g/L的游离脂肪酸，产率为每克0.13 g，而以离子液体基酸催化的竹水解物作为原料时，仅产生0.65 g/L的游离脂肪酸。结果表明，经过离子液体预处理的酶催化竹水解物可以作为游离脂肪酸生产的高效原料。
