Every day, chemical factories produce a wide range of products that will be extremely difficult to do without in a modern society; everything from drugs like insulin and antibiotics to fertilizers.
The basis of these products is often bacteria, which can produce chemicals and drugs efficiently while generating no toxic side products, thus appealing to the environment and sustainability.
A major challenge for these worker bacteria is that they may need to be exposed to different stressors in order to produce the desired product: some bacteria need to be exposed to high heat, others to high pH values and still others to organic solvents. Even if industrial bacteria are resistant, this often leads to their death and ultimately low efficiency.
Changzhu Wu, head of research at the Department of Chemistry, Physics and Pharmacy at the University of Southern Denmark, and his research team are working to develop more sustainable chemical processes, and they are now presenting a new technique that makes bacterial cells more robust and efficient for various chemical synthesis under harsh application conditions.
The team describes their new method based on the model bacterium E.coli in the scientific journal Communication Nature.
Most people probably think of E.coli as a bacteria that can contaminate drinking water and cause illness, but most bacteria of this species are found naturally in our intestines and are harmless.
Make E. coli stronger
E.coli is widely used to produce many important kinds of drugs and chemicals in industry because it grows rapidly and is both easy and safe to work with.
“But like other bacteria in industry, you lose a lot of them along the way. They just die from the harsh conditions given to them in the process, and that reduces efficiency,” says Changzhu Wu.
His idea is therefore to put the E.coli bacteria in a kind of protective suit so that they become more resistant.
The new protective suit is made of dopamine nanoparticles (which in chemist circles are known to protect against external stressors like light), and the recipe is simple: E.coli the bacteria, dopamine and liquid are mixed, and immediately afterwards the dopamine attaches to the surface of the cells of the bacteria in the form of nanoparticles.
“With the protective suit, the bacteria is protected against UV rays, heat and several organic solvents”, write the researchers in their scientific article.
Good for durability
A E.coli a bacterium without a protective suit will rarely survive more than two hours if exposed to UV rays. With the protective suit, more than 85% are still alive after two hours.
The researchers also tested the bacteria’s response to drastic phase changes (eg, being in a gaseous phase that turns into liquid, from liquid to solid, etc.). Here, 90% of unprotected bacterial cells died, while 80% of protected cells survived.
“With such high survival rates, we can increase the production of chemicals in E.coli bacteria, which is good for the environment and sustainability,” concludes Changzhu Wu.
Industrial use of bacteria, examples:
- Corynebacterium glutamicum for the production of lysine, nutritional supplement in feed, food and beverage industries.
- Penicillium chrysogenum for the production of penicillin
- Streptomyces griseus for the production of streptomycin (antibiotics)
- Halomonas bluephagnesis for the production of PHB (plastics)
- Kloeckera apiculata for the production of alcohol.
- E.coli for the production of insulin and growth hormones.