New cold-tolerant bacteria produce red bio-pigment with anti-germ properties

Jul 12, 2021

A team of researchers from Shoolini University in Himachal Pradesh, India, has discovered a psychrophilic strain of bacteria, called Rhodonellum psychrophilum GL8, at high altitude Pangong Tso Lake in the Himalayas. The red pigment isolated from this bacteria has antimicrobial, antifungal and growth stimulating properties of skin cells. This new bio-pigment promises to be useful for the development of smart antimicrobial fabrics, medicated dressings, and natural food dyes and preservatives.

Image Credit: Shoolini University

The dyes and their vivid colors have fascinated mankind even beyond recorded history. Archeology offers evidence of the dyeing of clothing during the Bronze Age and the height of Indus Valley civilization. Before the Industrial Revolution, the world relied on natural dyes from plants such as indigo, turmeric, saffron, beans, and paprika. The industrial revolution brought with it much cheaper and easily available synthetic dyes for use in the cosmetic, textile, pharmaceutical and food industries. But a side effect of this free application of synthetic dyes has been the constant contamination of our soil and water with the toxic chemicals released by these man-made products.

Over the past decades, people have become aware of the negative effects of synthetic dyes, and the demand for natural, non-toxic dyes has increased by 10-15% per year. In their search for environmentally friendly biocolourants, the researchers identified microbes as potential sources of pigments that promise to be environmentally friendly and economical, in addition to being non-toxic, inexpensive and readily available. Another advantage of using pigments of microbial origin is that, unlike some plant or fruit dyes, their production does not depend on seasonal fluctuations, and, given the good conditions for the growth of microbes, they can be produced in series like synthetic dyes!

So where to look for these color-creating creatures? According to a team of researchers from Shoolini University, India, in some of the most unimaginable and inhospitable environments it seems! Led by Professor Kamal Dev of the Department of Biotechnology and Microbiology at Shoolini University, the team discovered a new strain of an extremely cold-tolerant Gram-negative bacteria species from the icy waters of Pangong Tso Lake in the Himalayas, which produces a brilliant red pigment.

Synthetic molecules are gradually being replaced by biological molecules with various functions. The Himalayas hold within it a unique heritage of biological diversity. The overall objective of this study was to characterize the production of pigments by microbes from the high altitude lakes of the northwestern Himalayas to solve emerging health, food and environmental issues.. In our quest, we isolated and characterized a red pigment-producing strain of Rhodonellum psychrophilum.

Kamal Dev, Professor, Department of Biotechnology and Microbiology, Shoolini University

The researchers confirmed the new status of this strain of Rhodonellum psychrophilum, which they named “GL8”, by phylogenetic analysis, and subjected the isolated pigment to chromatographic and spectrometric techniques to identify the constituents. They found that the red pigment extracts contained a mixture of 2-methyl-3-butyl-prodigine, prodigiosine, 2-methyl-3hexyl-prodigine, 3,4-didehydrorhodopsin, anhydrorhodovibrin, alloxanthin and of tetradecanoyl-hexadecanoyl compounds. They further characterized the pigment by testing for bioactive properties. The results revealed that indeed, GL8 is special!

What is the particularity of this “GL8”? In their study published in Process biochemistry, the team reports that not only is the pigment produced by GL8 a wonderful dye, it also has a host of useful biological properties. For example, its broad spectrum antimicrobial activity makes it ideally suited for application in the manufacture of smart fabrics with an antimicrobial finish. Additionally, this pigment has antioxidant properties and acts as a bio-enhancer, increasing the effects of established antibiotics and antifungal agents, making it an ideal candidate for use as a food preservative. Interestingly, the pigment has also shown growth-stimulating properties of murine skin cells but no toxicity to human cells, which may open up avenues for its application to accelerate wound healing. In fact, the researchers have filed for patents based on their impressive findings, which they believe will provide unique local solutions to global problems of nutrition, medicine and the environment.

Puzzled as to why a tiny microbe possesses such a diversely potent pigment, Professor Dev speculates, “The melanin pigment in our skin protects us from harmful UV rays, which can cause skin cancer. Likewise, many living organisms produce unique pigments as survival strategies in response to harmful radiation, pollutants or freezing conditions.. “

Whatever the reason for its evolution, we cannot deny the usefulness of this pigment for humans. As researchers explore this wonderful microbe to further disentangle its superpowers, the world remains hopeful of applications of its currently identified antimicrobial properties to fight the growing incidences of pathogenic infections, such as the current COVID-19 pandemic. We cross fingers !