Organic alcohols, especially glycols , are an extremely important class of chemicals that can be widely used in the synthesis of high-performance materials such as polyester, polyurethane , polyether polyol , etc. In recent years, biological methods have been used to produce 1,3-propanediol (1,3-PDO), 1,4-butanediol (1,4-BDO), 1,3-butanediol (1,3-BDO), etc. Important progress has been achieved and industrialized production has been achieved.
,3 - Propylene glycol (1,3-PDO) is an important C3 platform compound. Its most important use is to condense with terephthalic acid to form propylene glycol terephthalate (PTT). PTT is a new type of Compared with PET, polyester fiber is anti-wrinkle, anti-pollution, easy to shape and easy to dye at room temperature, and has attracted much attention from the industry.
At present, more than 90% of the industrial production of 1,3-propanediol uses biological methods. In the early 21st century, DuPont Company of the United States successfully used engineering bacteria to convert corn hydrolyzed glucose into 1,3-propanediol. Since then, DuPont has formed a high degree of monopoly on the technology of producing 1,3-propanediol through biological fermentation.
"Enterprises and universities in many countries are studying the biosynthesis of 1,3-propanediol, but large-scale commercial applications have always been problematic. On the one hand, it is due to the monopoly of DuPont's patents. On the other hand, there are also various technical barriers in the industrialization process. There is also the issue of economics,” Chen Zhen said.
Chen Zhen studied at the Department of Chemical Engineering at Tsinghua University from 2001 to 2008. During his master's degree, he was also jointly trained at Tokyo Institute of Technology and received a master's degree from the school. After graduating with a master's degree, he went to Germany to study for a doctoral degree at the Technical University of Hamburg in Germany. From 2012 to 2013, he worked as a postdoctoral researcher at the Technical University of Hamburg. From 2013, he worked in the Department of Chemical Engineering of Tsinghua University, mainly developing new methods of synthetic biology for industrial applications. , including non-natural pathway design, discovery and transformation of new functional enzymes, atom-economic product design engineering, etc. Related technologies have been successfully applied to the industrial production of important products such as amino acids and their derivatives, bio-based glycols, and fine chemicals. .
The team at the Institute of Applied Chemistry of Tsinghua University where Chen Zhen works has been researching the production of 1,3-propanediol using glycerol as raw material since around 2000. It is the earliest domestic and foreign research group to realize the industrialization of 1,3-propanediol through biological methods. First, it solves the technical problem of high-end materials stuck in the neck.
Currently there are many teams conducting research on 1,3-propanediol in China, but most of them use glycerol as raw material to produce 1,3-propanediol. "We realized a long time ago that there are certain problems with using glycerol to produce 1,3-propanediol. Although glycerol is a by-product of biodiesel, it is also used in other fields, and its price fluctuates very sharply." Therefore. Chen Zhen's research group began to study how to break through the existing process very early, and has now achieved the direct production of 1,3-propanediol using a variety of raw materials such as glucose, xylose , sucrose and fiber hydrolyzate.
Construction of a 10,000-ton glycosyl 1,3-propanediol production device
Returned to Tsinghua to teach in 2013. Chen Zhen has been building a non-natural biosynthetic pathway for 1,3-propanediol. Currently, the team can produce glutamate Corynebacterium enables the conversion of multiple feedstocks to 1,3-propanediol for chassis cells. Corynebacterium glutamicum is an important industrial chassis that has been widely used in the production of amino acids and organic acids. "Corynebacterium glutamicum is considered to be biosafety , has very strong industrial robustness, can resist various environmental stresses and phages; and can adapt to different raw materials, has important application potential."
Recently, Chen Zhen's research group published a paper titled "Systems metabolism engineering of Corynebacterium glutamicum for high-level production of 1,3-propanediol from glucose and xylose", which simulated the effects of glutamate on glutamic acid through systematic metabolic network simulation. Corynebacterium was designed based on the 1,3-propanediol synthesis process of the chassis, and it was found that by utilizing the pyruvate -oxaloacetate-phosphoenolpyruvate cycle of Corynebacterium glutamicum, the glucose transport system of the PTS can be achieved without destroying it. Efficiently synthesize 1,3-propanediol, providing a design and optimization solution different from DuPont for the biomanufacturing of 1,3-propanediol, and this route has a wider substrate utilization spectrum and can effectively utilize glucose, xylose, Sucrose, fiber hydrolyzate, etc. are used as raw materials to produce 1,3-propanediol.
Figure 丨 Metabolic engineering strategy for designing and creating engineered Corynebacterium glutamicum for 1,3-propanediol production (Source: Research paper)
" This technology can not only convert a variety of raw materials into 1,3-propanediol, but also does not require the use of expensive excipients such as yeast powder in the production process. After optimization of the pilot process, output, yield, production efficiency, Key indicators such as product purity have reached or exceeded DuPont's industrialization level. ” Chen Zhen said.
In addition to the technical route using glycerol as an intermediate metabolite described in this article, Chen Zhen’s team has developed multiple non-natural 1,3-propanediol biosynthetic pathways, which can be used without adding vitamin B12 Directly convert a variety of raw materials to synthesize 1,3-propanediol under certain conditions, including artificial pathways using homoserine or trihydroxypropionic acid as intermediate metabolites, which can further reduce the production cost of 1,3-propanediol.
" In the past few years. In 2017, we have built two industrial units with an annual output of 10,000 tons of 1,3-propanediol using glycerin as raw material. We are currently building a new industrial unit with an annual output of 10,000 tons of 1,3-propanediol using sugar as raw material. We The goal is to combine synthetic biology with engineering technology, promote the sustainable development of technology, and become an international leader in 1,3-propanediol synthesis technology and industry.".
He also revealed that in addition to Corynebacterium glutamicum, its subject Another synthetic biology platform developed by the group is Vibrio natriureticus (the fastest growing microorganism discovered so far). In addition to producing 1,3-propanediol, the current laboratory is also developing ethylene glycol and 1,3- Monomers of other bio-based materials such as butanediol, 1,4-butanediol and 1,5-pentanediol, as well as synthesis technologies for high value-added products such as bird's nest acid and icodoine
Atoms that improve the biotransformation process. Economy is of great significance to improving the economic competitiveness of the biomanufacturing industry.
How to improve the economic competitiveness of the biosynthetic process is one of the difficulties for synthetic biology technology to move towards industrialization.
"When using synthetic biology for biosynthetic design. The usual goal is to minimize the generation of by-products and convert raw materials into a single product as much as possible. However, for many products, the raw material utilization efficiency of this process is very low. For example, most of the oxygen in glucose will become into , carbon dioxide, , etc., making the mass conversion rate of raw materials to products less than 50%. Traditional chemical processes such as petroleum refining will also produce a variety of by-products, but they will separate all products into useful products and realize full utilization of raw materials. This refining concept is very important for improving the efficiency of biological processes. Economic competitiveness has important reference significance. "
Chen Zhen's team relied on their chemical engineering background to propose and apply the concept of "atom-economic product design engineering" earlier to overcome the problem of low atom utilization in the biological conversion process and improve the economy of the biological manufacturing process.
Figure 丨 Factory producing 1,3-propylene glycol (Source: Respondent)
Atomic economy:
was first proposed by Professor B.M. Trost of Stanford University in the United States. He pointed out that traditionally, only economics is used to measure chemical processes Whether it is a feasible approach, it is clearly pointed out that a new standard should be used to evaluate the chemical process, namely selectivity and atom economy. Atom economy considers how many atoms of the raw materials enter the product during the chemical reaction. This standard requires both saving non-renewable resources as much as possible and minimizing waste emissions. B.M. Trost won the 1998 US Presidential Green Chemistry Challenge Award.
Chen Zhen told Shenghui SynBio, “Synthetic biology has given great potential to pathway design. The concept of product design engineering of atom economy is actually to conduct a comprehensive analysis of the raw material system and product system when using synthetic biology tools to design biosynthetic systems. Consider and design, comprehensively consider the degree of reduction of raw materials and products, the physical and chemical properties of products, the value of raw materials and products, etc., and design a biological transformation system coupling atoms and degree of reduction to achieve high atomic utilization throughout the entire biomanufacturing process. The product can also be easily separated. For example, when designing a pathway, a single raw material may not necessarily be considered. Raw materials with different reduction degrees can be coupled together and can complement each other during the biological transformation process, thereby achieving higher transformation efficiency. When designing the product system of the cell factory, taking into account the cost of raw materials, separation costs, and product value, products with different physical properties can be coupled together to transform the raw materials into atomically complementary and easy-to-separate products, improving the efficiency of the entire biological transfer process. Economic competitiveness. "
written at the end
At the end of the interview, Chen Zhenhe Shenghui SynBio shared some of his experiences in training students. He believes that universities need to cultivate comprehensive talents, cultivate students' systematic and innovative thinking, and be able to view and think about problems from different perspectives.
Secondly, we must have independent judgment and think about the future of synthetic biology from a higher perspective. We must not only understand the academic frontier but also consider the actual industrial problems and needs, and combine the perspectives of science, engineering and economics. new technologies to develop more targeted technical solutions.
Finally, we must pay attention to interdisciplinary subjects. Nowadays, the biological field is constantly changing, so we need multi-faceted capabilities to systematically integrate chemical engineering, automation, computers and biology.
