AsianScientist (Jul. 8, 2021) – For the first time, researchers from South Korea have successfully engineered bacteria capable of producing all seven colors of the rainbow. Their method was described in Advanced Science.
Regardless of whether you’ve ever tried Skittles—a brand of colorful fruit gummies—or not, you’ve surely heard of their slogan: taste the rainbow. Now regarded as one of the most iconic taglines in modern history, the phrase highlights just how pervasive colorants have become in our daily lives.
From the snacks we eat to the makeup we put on, we come into close contact with colorants every day—meaning that these compounds could impact our health in innocuous ways. Currently, most colorants are made of petroleum, which not only cause unexpected side effects, but also pose risks to the environment. For instance, the textile dyeing industry has gained notoriety for polluting rivers, especially in Asia.
Given these concerns, researchers have explored using microbes to produce safer, natural colorants. However, such a production method has yet to be realized on an industrial scale due to the low yield, despite the high costs involved.
This inspired a team of metabolic engineers at the Korea Advanced Institute of Science and Technology (KAIST) to find a better way to harness microbes for the production of natural colorants.
Led by Distinguished Professor Lee Sang Yup, the researchers focused on engineering the metabolism of Escherichia coli bacteria to efficiently produce seven natural pigments. Specifically, these were three kinds of carotenoids: astaxanthin (red), carotene (orange) and zeaxanthin (yellow) as well as four violacein derivatives: proviolacein (green), prodeoxyviolacein (blue), violacein (navy), and deoxyviolacein (purple).
When bacteria produce pigments, they typically accumulate inside the cell—which has limited capacity for storage. Working around this restriction, the team engineered the cell shape and generated tiny, spherical sacs within to increase the cell’s capacity for pigments.
To further promote production, the researchers also created tiny sacs on the cell’s exterior that could secrete the pigments—producing natural green and navy colorants for the first time. According to the team, their method could be used to efficiently produce industrially important colorants across the food, pharmaceutical and cosmetic industries, replacing petroleum-based synthetic colorants once and for all.
“As maintaining good health in an aging society is becoming increasingly important, we expect that the technology and strategies developed here will play pivotal roles in producing other valuable natural products of medical or nutritional importance,” concluded Lee.
The article can be found at: Yang et al. (2021) Production of Rainbow Colorants by Metabolically Engineered Escherichia coli.
Source: Korea Advanced Institute of Science and Technology; Photo: Shutterstock.
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