by Scott Chimileski
In late 2015, I wrote an STC post about plans for a microbial exhibition at the Harvard Museum of Natural History. That article, Bringing the Microbial World into Our Natural History Museums, and another written at ASM.org in 2016, Age of the Microzoo, describe the background and motivation behind the exhibition. Now, I am pleased to share with the STC audience that the exhibition is open to the public. It is called Microbial Life: A Universe at the Edge of Sight, and it opened this past February. I am one of the guest curators (along with Roberto) and I'm back to take you on an abbreviated virtual tour. I won't attempt to cover the entire exhibition here. Instead, I will share the overall layout and some of my personal favorite exhibits. Above all, I encourage you to visit if you are anywhere near Boston in the near future. The exhibition is open through at least September 2019!
The Microbial Life exhibition begins with a title wall devoted to the concept of biodiversity. We aimed to communicate one major point at this wall: most of the biodiversity on this planet is microbial. We made some calculations based on recent estimates of the total number of microbial species on Earth and the total number of plant and animal species in order to set the size of two circles that visually represent the relative scales of diversity. The large blue circle represents microbial species, and a tiny backlit dot in the center of that circle represents plant and animal species.
The wall to the left of the title wall answers the question "what is a microbe?" and surveys different kinds of microbes. Here we expand from the big concept of the vastness of microbial biodiversity to look at the relative size ranges of different kinds of organisms on Earth. There is a large chart showing the size ranges of some examples of animals, archaea, bacteria, protists, and viruses. We chose to define microbe within the exhibition based on size and the visual acuity of the human eye. We decided that the simplest and historically best supported definition is to treat all microscopic organisms as "microbes" or "microbial" organisms, rather than limiting the exhibits to bacteria and archaea. After all, when Charles Sedillot coined the word "microbe" in 1879, he included all organisms that must be viewed with a microscope. This first wall is also where we further categorize "microbes" into the domains Bacteria, Archaea, and Eukarya, shown with photographs of diverse microbial species.
In the corner of the space at the end of "what is a microbe" wall, there is an interactive, volunteer staffed microscopy station. This is the most important part of the exhibition in my opinion, because here visitors interact with microbial scientists and directly view living microbes. To staff this station, we assembled a team of graduate students and postdocs who work in local microbiology laboratories. These scientists generously volunteer their time for two hour shifts and carry out a few different demos using a microscope connected to a large screen. For example, in the kombucha biofilm demo, volunteers describe the process of making the fermented tea product kombucha. The volunteers remove a piece of the thick floating biofilm that develops as the tea ferments, prepare fresh slides and examine the biofilm under the microscope. In this way we show visitors the yeasts and bacteria that add flavor while building and living in the biofilm. This is a great sample to work with and talk about, since it is a diverse symbiotic community of bacteria and yeast (SCOBY for short). In another demo, we show a few different species of common soil bacteria growing as colonies on a Petri dish. We encourage visitors to gently smell the plates of Streptomyces and Myxococcus. We almost always hear the reaction we are looking for: "Wow, those bacteria smell like soil!" From there we talk about how the very smell of soil that we all know (and many enjoy) comes from soil bacteria, and is the molecule geosmin.
From the volunteer station, a full-scale kitchen is visible at the center of the exhibition space. The kitchen is an interactive display that acts as an example of a built environment, a man-made space. Like everywhere else on the planet, such a space is full of invisible microbial ecosystems. There are five touch screen panels, each focusing on a different topic related to microbes in kitchens and other built environments. One panel is called "My Home is My Microbial Castle." This panel shows a video of the "microbial cloud" that surrounds all of us, sending microbes out from our bodies to colonize surfaces in home and workplace. Another panel looks at microbial foods, with time-lapse videos of fermenting food and drinks. We also explore topics such as the "five-second rule" and the microbial breakdown of garbage.
One of the longer walls behind the kitchen goes on to feature a handful of other environments where microbes live. By then, we hope that visitors appreciate the idea that "microbes are everywhere." Knowing that we could not begin to cover every microbial ecosystem, we selected a few well-studied and relevant microbial hotspots. These include microbes in the atmosphere, in the soil, in freshwater, and in the ocean. My favorite exhibit on that wall is a display of living fungi and bacteria from soil. This is a case containing four large Petri plates that I change out every 6 weeks. I really enjoy that visitors can not only see the colonies up close, but also that repeat visitors can appreciate their development over time. One week a Streptomyces colony starts out white and by the following week it has doubled in diameter, become wrinkled, and has a bright blue halo due to the pigment actinorhodin which has been secreted into the surrounding medium. Likewise, Bacillus and Myxococcus colonies swarm across the medium (slowly!) before visitors' eyes. We've even seen evolution occur at the edge of colonies (a spreading phenotype), right here in the museum!
There's an area on microbes that live in "extreme" environments and that may live beyond Earth. We identify and show NASA images of some other places in our solar system, like Jupiter's moon Europa, and exoplanets beyond our solar system that might be hotbeds of alien microbial life. Every section includes a crystal sculpture of a microbe. In this extreme environment section the crystal sculpture is of the ever popular tardigrade, the famous survivor of an experiment in space. In a nearby nook there is a case containing images of several types of hydrothermal vents on loan from the Woods Hole Oceanographic Institute and a "microbial theatre" showing short documentaries of microbial research underway at Harvard.
Right around this area of the exhibition there is a very large Winogradsky column. This has been a very popular exhibit that visitors can walk fully around to see more living and colorful microbes. But I will not go into detail about the Winogradsky column here because it is the subject of my next post, coming up in a few days.
Finally, there is large section that covers "microbes and the animal body" through a series of vignettes into this expansive topic. Here we have a look at various sites of the human body relevant to health, such as the skin and the mouth. My favorite exhibit in this area is a large print of the "hedgehog" community within human dental plaque as seen through CLASI-FISH microscopy (we featured the "hedgehogs" here in STC). When I am showing this exhibit to others, I like to say that these dental plaque communities are like forests within our mouths, with a remarkable organization among the many different species present. I get mixed reactions form those who did not know this before, but the reactions always include some level of astonishment! Of course, I go on to say that most bacteria there are not the ones that cause cavities, and that by studying these communities, we may some day be able to limit the acid-producing species that causes cavities.
Microbial Life is most certainly not the only exhibition of microbes to be found. Beginning with the opening of Micropia, a museum devoted to the microbial world at the Artis Royal Zoo in Amsterdam in 2014, we are seeing a movement that brings microbes into more and more museums. Personally, we are involved in the major new permanent Invisible Worlds exhibition at the Eden Project in the UK and an upcoming bacteria exhibition at the Oxford University Natural History Museum. And we are now working on a Microbial Life exhibition at Parque Explora in Medellín, Colombia. Invisible or not, microbial life is the foundation of the biosphere. Microbes make up most of Earth's biodiversity. There is truly no end to the exciting stories to be shared from the microbial world. I continue my call that these and other efforts around the world are just the beginning!
I cannot finish this tour of the Microbial Life exhibition without thanking everyone else on the team. Roberto and I are fortunate to work with an amazing group at the Harvard Museums of Science and Culture, including Executive Director Jane Pickering, Director of Exhibitions Janis Sacco, Senior Designer Sylvie Laborde, and Jennifer Berglund, among others. Professors Colleen Cavanaugh, Andrew Knoll, and Peter Girguis also joined this combined effort as guest curators and scientific advisors. And we are very grateful to the Alfred P. Sloan Foundation, the National Science Foundation and Clark and Susan Bernard for supporting the exhibition.
*All images taken by and courtesy of Scott Chimileski
Scott Chimileski is a postdoctoral fellow in Roberto Kolter's laboratory at the Harvard Medical School in Boston, MA. Along with Roberto, he authored the book: Life at the Edge of Sight. More of his microbiology photography can be found on his portfolio website, Into the Microbial World.