Carboxysome Museum Exhibit

The cyanobacterium Prochlorococcus marinus Source: Image by Luke Thompson from Chisholm Lab and Nikki Watson from Whitehead, MIT

The story

Cyanobacteria are a common marine bacteria that are often called blue-green algae, most of us are familiar with them for their tendency to cause toxic algal blooms. Dr. Anthony Vecchiarelli, @CellfOrganized, studies them for their carboxysomes. Carboxysomes are icosahedron-shaped organelles packed with the carbon-fixing enzyme rubisco.

Icosahedron [Source](
Icosahedron Source.

Carboxysomes condense rubisco within a shell that allows carbon dixoide in, while blocking oxygen, which reduces rubisco’s rate of carbon fixation. Both actions increase the rate of carbon fixation to such an extent that only 2.5 mL of cyanobacteria can fix the same amount of carbon as a full-grown tree.

Electron micrograph of isolated carboxysomes. Scale bar = 100 nm. [Source]( doi:10.1371/journal.pbio.0050144
Electron micrograph of isolated carboxysomes. Scale bar = 100 nm. Source: doi:10.1371/journal.pbio.0050144

Together with Dr. Vecchiarelli, Melissa Westlake, the Assistant Director for Exhibits, and her staff, I turned the fascinating world of cyanobacteria and carboxysomes into the text for an all-ages museum exhibit at the Museum of Natural History at the University of Michigan.

“I have been working with the University of Michigan Museum of Natural History in the design of an NSF-funded “People and the Planet” exhibit. The exhibit highlights the roles carbon-fixing cyanobacteria have in climate change. Dr. Ada Hagan joined our project at a point where the team was having difficulty conveying complex and disjointed scientific information that was accessible to the general public. Dr. Hagan’s impact on the exhibit design and direction was immediate. She took these scientific findings and turned them into a concise, fun, and compelling story. With this story as a template, the project team has a very clear idea of how to build the exhibit. I would definitely work with Dr. Hagan again!” - Dr. Vecchiarelli

Sample text

Algae and the climate crisis

Humans have put too much carbon dioxide into the air and caused climate change. Now we have scary weather events and algal blooms! Algal blooms are caused by cyanobacteria (aka blue-green algae) using the extra carbon dioxide for photosynthesis. Scientists think that cyanobacteria created the first oxygen on Earth, causing the Great Oxygenation Event (GOE) almost 2 billion years ago. The GOE both cooled the planet and allowed our oxygen-breathing ancestors to evolve. Could cyanobacteria help us again?

The Key to Carboxysomes (Interactive)


  • Oxygen (key)
  • Carbon dioxide (key)
  • Carboxysome pore (keyhole)
  • Mechanism (i.e., what happens when they use the correct key)

Instructions: Can you use these keys to solve the carboxysome riddle?

Oxygen and carbon dioxide are chemicals, and keys, too.
What is it that they do?
Open the carboxysome pore,
Which is kind of like a door.
But only one will fit, because nature is smart,
And cyanobacteria keep rubisco apart
From the chemical that slows carbon fixation.
Which key fits the pore for sugar formation?

Renders of the exhibit upon completion. Credit: [Alison Campbell](, Exhibits Graphic Designer.
Renders of the exhibit upon completion. Credit: Alison Campbell, Exhibits Graphic Designer.
Ada K. Hagan, Ph.D.
Ada K. Hagan, Ph.D.
Owner, Lead Consultant

I am a microbiologist with a passion for making science accessible. I hope to use my background in communications and higher education to help make scientific concepts more easily understood and make the academy more inclusive to future scientists from all backgrounds.