The words bacteria and beauty are not usually associated. But some bacteria make beautiful colors that span the entire rainbow. And one type of bacteria called Streptomyces coelicolor makes an antibiotic with a lovely blue pigment. This blue-colored antibiotic, called actinorhodin, inspired microbiologist Dr. Vineetha Zacharia, a postdoctoral researcher at the University of California, Berkeley studying this soil bacterium, to use it like watercolor paint to create art.
So, read on or listen to the podcast episode to learn about her work with Streptomyces coelicolor and how she got into what she calls “Actino Art.”
Topics covered in this episode:
- Streptomyces coelicolor, a colorful bacterium
- Life cycle and cell types
- Antibiotics and other helpful chemicals Streptomyces produce
- Painting with antibiotics
- At-home microbiology activity: Actino Art
Listen to my episode with Dr. Vineetha Zacharia
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Streptomyces coelicolor, a colorful bacterium
The colorful bacterium Streptomyces coelicolor lives in the soil and provides a fascinating study subject for Vineetha. She researches what impact its development. And while she grows it in the lab for her work, this bacterium produces a blue-colored antibiotic called actinorhodin. And one day, she decided to try using this blue pigment like watercolor paint and started doing what she calls Actino Art.
But before we get into her art, here’s some background about these bacteria. First, what are they doing in the soil? “Soil bacteria are really important, just from an ecological perspective — they are producers of so many different chemical compounds that are important medically and industrially. And in nature, they’re important for decomposing organic matter, ” says Vineetha.
There are also conversations going on between microbes and other organisms. But the way they do their talking is different from how we do — they use these chemicals, some of which are these antibiotics like actinorhodin.
Life cycle and cell types
Because Vineetha studies the development of Streptomyces, she looks into its fascinating life cycle, which is multicellular. The idea of bacteria having a multicellular lifestyle is a bit counterintuitive because when you take a general microbiology course, you learn that bacteria are unicellular and fungi are the ones that can live multicellular lifestyles. However, there are always exceptions to the rule. And Streptomyces is a major one. “Streptomyces were actually originally mistaken for fungi because of its fuzzy appearance,” says Vineetha.
In this life cycle, Streptomyces start out as spores (giving it that fuzzy appearance), which have all the genetic information necessary to start the lifecycle. And when the conditions are favorable, the spores begin to grow.
When growing, they are vegetative hyphae, a kind of strand-like mycelium, which is really intriguing for bacteria since mycelium is a concept usually associated with fungi. They produce vegetative hyphae early in the lifecycle when they begin taking in nutrients and making things it needs.
They also make structures called aerial hyphae, which are coated with water-resistant proteins to break the air-water surface and grow upward. Those hyphae eventually turn into spores. And the spore chains disperse into the environment.
Streptomyces coelicolor can produce the blue pigment actinorhodin while it’s growing and also another red-pigmented antibiotic, prodigiosin.
Another type of cell they make is called explorer cells. This new growth type of Streptomyces was discovered by Marie Elliot’s lab. It’s “quite amazing how these explorer cells can traverse across media and find new sources of nutrients,” says Vineetha, because they typically don’t have a way of moving on their own.
Antibiotics and other helpful chemicals Streptomyces produce
Streptomyces is a part of a group of bacteria called actinomycetes responsible for making about 70% of the antibiotics we use in humans clinically.
Besides antibiotics, Streptomyces make compounds with antifungal properties and anticancer properties. For example, prodigiosin has immunosuppressive and anticancer properties.
But why do they make these compounds? “From an ecological perspective, these compounds are really important for maintaining communication with other organisms, including not only other bacteria but also organisms from other kingdoms like fungi and insects,” says Vineetha.
For the insects, they provide protective compounds from harmful microbes. And for themselves, these compounds serve as a means of defense when interacting with different microbes and competing for resources. “When it gets dicey, they’re able to produce these compounds that can confer this advantage to them to survive.”
It’s amazing to think that there’s so much going on. Everything is more connected than we realize. We often put organisms in these categories and only think they operate within those categories, not between them.
Painting with antibiotics
These colorful antibiotics, like the blue actinorhodin, inspired Vineetha to try using them as watercolor paint.
“I was curious one day of what it would look like on paper. I had some plates leftover from an experiment on my bench, and they have these beautiful droplets. And I also happened to have a paintbrush, which was related to another experiment. So I dipped that into the secreted droplet, put that onto paper, and it was just mind-blowing because it really felt like I was painting with the watercolor paint. And it makes sense because this compound is water-soluble.”
As Vineetha looked into it more, she discovered that others have done similar things, using actinorhodin as a sort of “biopigment” for educational purposes and dyeing different fabrics to help create more sustainable dyes.
Vineetha has enjoyed painting from a young age since her parents bought her a paint set. “I would always doodle and enjoyed paints.” And her mom’s zoology notebook that she kept in college inspired the theme of many of her paintings. “It was so detailed and beautiful. That’s what inspires a lot of my art now and why I gravitate towards doing a lot of wildlife in my Actino Art.” Overall, she loves painting because it’s “ a great way of being able to express creativity and also serves as a stress reliever. It’s really peaceful.”
To give you an idea of what it looks like for the Streptomyces colonies to grow and then produce actinorhodin, Vineetha takes a “spore stock” and streaks it out on a petri dish, then lets it grow for a couple of days. The colonies begin to form “bald” colonies, lacking the hairy aerial hyphae early in its lifecycle. Then, as it grows, more of the white fuzzy aerial mycelium starts to form, and then comes the reddish blue pigment. Eventually, the entire petri dish turns blue because of actinorhodin. And you can also see this antibiotic as droplets on the surface of colonies.
Something that makes painting with actinorhodin even more fun is that it can change color because it is pH-responsive. At basic conditions (think of the pH of soap and drain cleaner), it is blue, and at acidic conditions (think of the pH of vinegar or lemon juice), it turns red.
You can watch Vineetha demonstrate the pH-responsive properties of actinorhodin in this video and see the colors in this photo. In the video, she paints over the piece of art, originally blue, with dilute acetic acid (vinegar), and it turns red.
At-home microbiology activity
For the at-home microbiology activity, Vineetha shares on the podcast a way to explore Actino Art at home. In the paper, In Living Color: Bacterial Pigments as an Untapped Resource in the Classroom and Beyond, Louise K. Charkoudian outlines how to work with Streptomyces and create art with it directly on media and with its pigments. You can find many materials for this activity at the grocery store or may even already have them at home.
Links & Resources
- Activity: In Living Color: Bacterial Pigments as an Untapped Resource in the Classroom and Beyond
- A scent that Streptomyces make: Geosmin: the smell of soil and rain (blog post and podcast episode)
- Colorful Microbes: Red, White, and Blue Microbes (blog post)
- More on soil microbes: What’s in the Soil? A Primer to Soil Bacteria (blog post)
Connect with Dr. Vineetha Zacharia
Dr. Vineetha Zacharia is a Postdoctoral researcher at the University of California, Berkeley, in Matthew Traxler’s lab. She studies the factors that influence the development of the soil bacterium, Streptomyces coelicolor, which produces a diverse array of medically and industrially relevant natural products. She also paints using secreted pigmented antibiotics from this awesome actinomycete!
Connect with Dr. Vineetha Zacharia: Twitter
The superpowers of bacteria: Dr. Sarah Wettstadt (BacterialWorld)
