On October 20, when the reporter interviewed Professor Li Aitao of the College of Life Sciences of Hubei University and the State Key Laboratory of Biocatalatation and Enzyme Engineering, Li Aitao's research team has made a major breakthrough in the field of nylon monomer preparation, breaking the existing industrial synthesis of nylon monomer caused by high pollution and energy consumption of environmental pollution constraints, to find a new method for the preparation of nylon monomer.

Researchers have designed a new artificial biosynthesis pathway for nylon monomer by designing a microbial community catalytic system. According to Li, the artificial biosynthesis system adopts the catalytic strategy of modularization and microbial flora, and divides the eight enzymes in the entire biosynthesis pathway into three modules, which are respectively expressed in three types of E. coli, so as to obtain three modular cell catalysts. Then, using the "plug and play" assembly strategy, the three cells were combined to build the E. coli microbiome catalytic system, and finally realized the efficient bioconversion of cyclohexane or cyclohexanol to adipic acid. This research result provides a new idea for the synthesis of nylon monomer by virtue of its remarkable advantage of high efficiency and green.

"Nylon 66 is prepared from the condensation of adipic acid and hexanediamine, and adipic acid is the main monomer. In the traditional industry, its synthesis mainly depends on the multi-step chemical oxidation process with high pollution and high energy consumption." Li Aitao introduced that the process requires the use of a large amount of corrosive nitric acid, while producing a large amount of NO, N2O and other harmful greenhouse gases, causing many environmental problems, such as global warming, ozone hole, etc., so seriously restricting the development of nylon 66 industry.

In order to deal with the above challenges, Li Aitao team based on the previous accumulation in biocatalysis, designed an artificial biosynthesis system, which can catalyze the synthesis of cyclohexane to nylon 66 monomer adipic acid. Li further introduced: "The process can be catalyzed under mild conditions (room temperature, atmospheric pressure and water phase), using self-contained coenzyme self-cycling, does not need any exogenous expensive coenzyme, low cost. At the same time, there is no accumulation of intermediate products during the reaction process, and the selectivity is high, the product is single, and the subsequent separation and purification is simple."

"In addition, using the rational design of the E. coli microbiome as a catalyst, can achieve a variety of cycloalkanes or cycloanols (C5~C8) to obtain different α ,ω The synthesis of -dicarboxylic acid fully proves the universality of the method. Finally, the whole bioconversion reaction was amplified in the fermenter, and the product of adipic acid was successfully amplified and prepared. This artificial biosynthesis system is the first method to achieve large-scale biosynthesis α ,ω -dicarboxylic acids form an important foundation." Li Aitao said.

Nylon as a very widely used synthetic fiber, is used in many important fields related to the national economy and people's livelihood. In the next step, Li Aitao's research team will further improve the catalytic efficiency of the enzyme, make the catalytic performance of the 8 enzymes consistent, break the bottleneck of the rate-limiting enzyme, and mutate the enzyme by designing and reforming the enzyme molecule to give it higher catalytic performance, so as to improve the efficiency of the entire artificial biosynthesis of nylon monomer.