"Green" blue paint

It is known that many food and textile dyes are not harmless to humans, and in the production process they harm the environment. For this reason, today scientists are actively looking for ways to obtain natural pigments and seek help in the search for nature itself.

For example, the colonies of many fungi and bacteria are distinguished by a bright color, which is caused either by the release into the environment of colored substances, or by the special pigmentation of the cells themselves. The variety of pigment forms among microorganisms is explained by the fact that pigments act as a tool of protection against negative environmental effects, and therefore are resistant to them and are of potential interest for food and textile production.

There is a demand for renewable dyes in the textile market, photo WEB

Scientific research in this direction has been conducted for a long time, but their results usually do not immediately find practical application. There are, however, pleasant exceptions, one of which was the opening of a team from the United Institute of Bioenergy. In the course of research, they managed to obtain a natural blue dye, indigoidin, the artificial analogue of which is now actively used in the textile industry.

“Previously, this pigment was obtained from plants, and later its synthetic substitute was created, which is used to dye fabrics to this day. The process of its production is simple, effective and inexpensive, but is based on the use of toxic substances and leaves waste hazardous to the environment. Our method allows us to produce blue pigment using cheap, nature-friendly sources of carbon, rather than hard precursors,” says A. Mukhopadhyay, the lead researcher of the group.

Aindrila Mukhopadhyay, Leading Researcher at the Joint Institute of Bioenergy, photo ©jbei.org

Scientists got indigoidin from mushrooms, and, perhaps, started this new era of dyes. They believe that the developed method can be used for the production of different coloring matter from other types of fungi and bacteria, which greatly increases the significance of the discovery. The “mushroom” indigoidin is not inferior to the brightness and saturation of artificial indigo, with which the whole world paints jeans, and therefore is capable of becoming a healthier and more eco-friendly alternative.

However, this experience of obtaining natural paints using microorganisms is not the only one. Three years ago, scientists at the University of Utah discovered that indigoidin is capable of producing E. coli. True, the bacteria had to undergo a series of genetic changes - they have “by nature” only one gene responsible for producing pigment, and in order to activate the process, scientists made several copies of it. Today the team has already received a patent for its invention and is trying to bring it to market. It is noteworthy that indigoidin colibacilli are thoroughly cleaned, because it is suitable for use in the production of food and beverages, and cosmetics.

Indigoidin from E. coli, photo © techcult.ru

On a commercial scale, pigment of the bacteria genus Micrococcus secrete is also used today. It became the basis for food colors of red shades. The technology of its production is simple - bacterias are grown on glycerin, then dried and poured with an organic solvent, into which the coloring matter passes. Interestingly, by changing the conditions, you can get the dyes in the spectrum from purple to orange.

Pigment of bacteria of the genus Micrococcus has become the basis of food colors of red shades, photo WEB

It is worth noting that in nature, indigoidin protects cells from UV radiation, and the carotenoid pigments of Micrococcus possess high antioxidant activity and prevent attacks of carcinogens. This means that such dyes-metabolites are resistant to the negative effects of the environment and safe for humans. Another bonus is that their industrial production does not harm the environment.

Victoria Romanova, Russia, Moscow

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