Synthetic biology is a science that uses genome sequencing technology, computer simulation technology, bioengineering technology and chemical synthesis technology, etc., under the guidance of engineering thinking, to synthesize biological functional elements, devices and systems. It is an emerging cross-integration discipline that carries out genetic design and transformation of organisms so that they have biological functions that meet human needs, and even creates new biological systems. disruptive technology.
The influence of synthetic biology has risen rapidly since the 21st century. It has been hailed as the key to understanding life and a disruptive technology that changes the future. The use of synthetic biology technology to produce target products has a series of advantages such as high efficiency, economy, and environmental friendliness. Therefore, the research and development and application of various chemicals, new unnatural medicines, natural products, etc. using this method are in full swing.
Synthetic biology of natural products
Synthetic biology of natural products is mainly divided into three areas
- First, research is performed on a known drug whose chemical composition and its biosynthetic pathway are known, with the main goal of improving the production process and in a host that is more easily controlled than natural drugs.
- Second, to investigate the existence of unknown compounds that are present in bacterial genomes but have not yet been discovered, the main goal of synthetic biology is to awaken the biosynthesis of cryptic metabolites, facilitate their chemical and functional characterization, and ultimately utilize Known methods to achieve production.
- Third, screen the “unknown unknowns”. Based on current genome discoveries, such molecules belonging to new chemical classes cannot be discovered for the time being.
Microbial natural products
Microbial natural products are a major source of innovation in novel biopharmaceuticals
Microbial natural products have always been the main source of new biological drug innovation, and are currently an important resource for the development of clinical antibacterial, antitumor, immunosuppressive and other drugs. With the increasing number of clinical drug-resistant bacteria, the continuous emergence of new pathogenic bacteria and viruses, and the gradual increase in the difficulty of mining natural products with new skeletons, the development of new microbial drugs is facing great challenges.
Traditional microbial drug development is accomplished through large-scale fermentation, cultivation and isolation and extraction of microorganisms. However, many natural strains that can produce valuable active compounds have disadvantages such as difficulty in cultivation, slow growth rate and low yield, which limit the related industrialization. Production.
As a frontier discipline in the fields of life sciences and medicine in the 21st century, which promotes innovative breakthroughs and interdisciplinary integration, the rise of synthetic biology provides new ideas and methods for solving the dilemma of drug research and development. On the premise of fully understanding the synthesis pathway of microbial drugs, based on the principles of synthetic biology, we can design and transform dominant microbial strains into heterologous and high-yielding chassis cells for the production of more active natural products to break through the bottleneck of natural drug production. .
High-density fermentation of engineered bacteria
Increasing the culture density of engineered bacteria and increasing the specific productivity of the product
Through the research on the biosynthesis of natural products, the enzymes required for the synthesis of natural products were found, and the full-length fragments of the target DNA were obtained by designing specific primers to amplify, and then digested with the corresponding restriction enzymes, Then, DNA ligase is used to insert it into the carrier to obtain recombinant DNA molecules, and finally the recombinant DNA molecules are introduced into recipient cells, and the recipient cells are amplified. Commonly used receptor cells include Escherichia coli, Bacillus subtilis, Agrobacterium, yeast, animal and plant cells, etc.
This kind of bacteria and cell lines that use genetic engineering to express foreign genes efficiently are generally called “engineered bacteria” (as shown in the figure below). The growth and reproduction of engineering bacteria need to ensure the concentration of various nutrients required for their growth and metabolism, limit the concentration of harmful substances that hinder growth and metabolism, and maintain the appropriate range of parameters such as fermentation temperature, pH value, and dissolved oxygen.
This kind of bacteria and cell lines that use genetic engineering to express foreign genes efficiently are generally called “engineered bacteria” (as shown in the figure below). The growth and reproduction of engineering bacteria need to ensure the concentration of various nutrients required for their growth and metabolism, limit the concentration of harmful substances that hinder growth and metabolism, and maintain the appropriate range of parameters such as fermentation temperature, pH value, and dissolved oxygen.
In order to increase the culture density of engineered bacteria and increase the specific productivity of the product (the yield of the product per unit volume and unit time), high-density fermentation technology is usually used, that is, the growth of microorganisms in liquid culture when the cell population density exceeds that of conventional culture by more than 10 times. state-of-the-art cultivation techniques.
This technology can not only reduce the culture volume and strengthen the downstream separation and extraction, but also shorten the production cycle and reduce equipment investment, thereby reducing production costs and improving market competitiveness.
The methods of high-density culture mainly include dialysis culture, cell cycle culture, and fed-batch culture. The organic combination of this high-density culture technology and recombinant DNA technology enables large-scale production of natural proteins that could not be obtained in large quantities.