Synthetic Biology


In 2015, a non-governmental organization has listed 116 products or industrial applications coming from synthetic biology that are either on the market or close to being commercialized. These products or applications come from all biotechnological sectors.

Drugs Artemisinin is an effective drug against advanced stages of malaria. It is extracted from a plant used in traditional Chinese medicine known as sweet wormwood, but with low efficiency therefore it is expensive. It can be produced by chemical synthesis, but the process is very laborious and difficult to industrialize, in part due to the asymmetric geometry of the molecule.

A yeast strain has been made by synthetic biology, which produces artemisinic acid, a precursor of this drug, which is then transformed by a chemical method into the artemisinin drug. The product purity and availability have been significantly improved.
Since 2013, between 60 and 100 tons of artemisinin are produced annually in a factory, which represents between one third and one fifth of the world needs.

Diagnosis Patients with AIDS or hepatitis or both diseases are monitored by an effective diagnostic tool that can highlight with great sensitivity the ribonucleic acid (RNA) specific to certain viruses. The tool is able to detect very low levels of RNA in a sample solution, down to eight molecules. This extreme sensitivity is necessary because the patients are generally treated to eliminate the virus, whose residual concentrations are consequently very low. A method combining synthetic chemistry and synthetic biology has permitted to reach the required sensitivity. This method allows annual monitoring of 400 000 patients.

Biofuels Blue-green algae produce small quantities of hydrocarbons. The genes involved in this process have been identified and introduced into the genome of the Escherichia coli bacterium, a normal resident of our intestinal tract. Using synthetic biology, the bacterial metabolism has been modified to produce in a factory hydrocarbons that can be used as biofuels. Other approaches make use of yeasts that naturally produce lots of lipids that may be used as such, or as precursors of biofuels.

Biomaterials Isoprene, used in rubber production, is naturally produced in small quantities by almost all living creatures (including humans, plants and bacteria). The gene encoding the enzyme of isoprene synthesis has been identified only in plants like the rubber tree, capable of synthesizing natural rubber, a scarce resource. Synthetic biology has allowed the design of a new gene encoding this enzyme that, moreover, is optimized to operate in a specific microorganism. The objective is to develop biochemical production of synthetic rubber, currently only produced from petroleum.

Isobutene, a precursor to plastics, rubbers, lubricators and fuels, can now be industrially produced by a metabolic pathway that has no known counterpart in the natural world, from renewable resources (agriculture or domestic wastes, starch, sugar cane or beetroot). Isobutene is produced as a gas, which allows its easy and continuous extraction from the bacterial culture, thus preventing any toxic effect.

Bioremediation Bacteria such as and Rhodococcus sp. or Pseudomonas putida can absorb small amounts of petroleum and degrade it into less toxic substances. However, they prefer to feed on traditional of carbon such as glucose. Using synthetic biology, some non-essential genes can be switched off to change the bacteria's metabolism. By blocking sugar absorption, the bacteria are forced to consume and degrade toxins.

Detectors Millions of people worldwide are affected by arsenic poisoning of drinking water, which has slow but cumulative effects and is lethal to many people. Conventional detection techniques, based on fluorescence, are expensive, tedious and require sending water samples to laboratories. In countries where water wells are often contaminated by arsenic (in Bangladesh, one well out of two to four are), the wells cannot be systemically tested for this poison, the more so that its concentration varies with time.

The Escherichia coli bacteria have been modified by synthetic biology and turned into an arsenic detector. The bacterium has a detoxification system activated by arsenic, as well as the ability to degrade lactose into lactic acid. The gene of the detoxification system has been isolated and coupled to the gene of lactose degradation. Thus, in the presence of arsenic, lactic acid is produced by the modified bacterium, the acidity increases in the medium and can be detected by a simple pH test carried out with litmus paper. This process has recently been improved, notably to avoid any possibility of a contact between the bacteria and the people who manipulate the test and often are not versed in microbiology.

Synthetic biology needs powerful tools to succeed in these applications.

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