Small Matters: Microbes and Their Role in Conservation

Small Matters: Microbes and Their Role in Conservation
The Center for Biodiversity and Conservation's Twelfth Annual Symposium
Thursday and Friday, April 26 and 27, 2007
American Museum of Natural History

Responses

Microbes are minute, mostly single-celled organisms, including bacteria, fungi and protozoa that are usually invisible to the naked eye. Maybe because of their tiny size and because they are difficult to study, microbes have gone largely ignored, leading renowned biologist and author Edward O. Wilson to refer to microbes as the ‘black hole of biological systematics.” Yet recent scientific and technological advancements tell us that microbes are the ancestors of all organisms, they are the support for all ecosystems, and that without them, life on Earth would cease to exist. The American Museum of Natural History paid tribute to these essential, but much over looked creatures, with its twelfth spring symposium entitled “Small Matters: Microbes and their Role in Conservation.” On April 26th and 27th, microbiologists, conservation biologists, disease ecologists and others, gathered in the state-of-the-art Kaufmann Auditorium to discuss the wealth of roles that microbes play on the planet and the various ways in which microbial communities are impacted by the loss of biodiversity. The two-day event, including an evening panel discussion held in the LeFrak Theater geared specifically towards a lay audience, left no doubt in the minds of those less informed on this technical and often daunting subject as to the critical role microbes play in the universe, and why it’s so important to think about them.

Thinking about microbes, because of their tiny size, can present its own set of challenges, and may require, on the part of the uninitiated, a certain stretch of the imagination. How big are they exactly? Columbia University professor, Shahid Naeem, told the audience that there are one hundred million to a billion microbes in just one gram of soil. Oregon State Microbiology professor Stephen Giovannoni explained that if, lying beneath the Museum’s whale replica, one imagined one self as a microbe and the whale as an earthworm then one might get an idea of a microbe’s proportions. In other words, it’s easy for those of us less “microbial” in orientation to overlook, on our paths to school, to work, to the grocery store--or even to the Hall of Ocean Life --these minute organisms.

The lay community is not alone in giving microbes short shrift. Scientists have typically paid far more attention to charismatic mega fauna (the larger animals, weighing ten kilograms or more such as bears, deer, and crocodiles) than they have paid to the microbial universe—that “other cosmos” as Dr. Naeem called it. However, in the late 1990’s, the emerging technology of molecular biology and the advent of genetic analysis provided scientists with new tools for studying the structure and function of genes, and for understanding the genetic relationship between organisms, advancements that revolutionized the field of microbiology. To quote Eleanor Sterling, Director of the Center for Biodiversity and Conservation at the AMNH, “We have a better sense now of all we’ve been missing in food webs, in oceans, in mud, in soil, and even in our mouths.” Dr. Laura Katz, Associate Professor of Biology at Smith College, drew attention to the pioneering discoveries of microbiologist Carl Woese of the University of Illinois, who in 1977, discovered a new domain in life called “Archaea,” a type of microbe differing both genetically and metabolically from all other forms of life. Recognizing the enormous diversity of microbial lineages, Woese claimed that Archaea were more closely related to Eukaryotes (plants, animals and fungi) than to bacteria. The so-called “Woesian Revolution” teaches among other things, that all of life is based on the same biochemistry, and no single organism outranks others in importance, or as Dr. Katz exclaimed, “You cannot be a lower E. coli!”.

As the two-day symposium made clear, even with the aid of these new techniques and discoveries, microbial life to a large extent remains shrouded in mystery. It was estimated that while roughly thirty million microbial species exist, most of them have yet to be identified and studied. A complicating factor, as Dr. James Tiedje, Director of the Center for Microbial Ecology at Michigan State University explained, is that, within the microbial world, there is no set definition of a species. Microbial lineages evolve not just vertically but also laterally through a process known as “horizontal gene transfer,” or the transfer of genetic material across species boundaries. As Dr. Tiedje further explained, two lineages are said to belong to the same species when purified DNA molecules show at least 70% re-association through hybridization, but that percentage, he explained, is an arbitrary cut-off. All this is to say that the current system for defining species, while functional, remains inadequate, so that the vast majority of microbial species remain unidentified. Dr. Rita Colwell, Distinguished Professor at the University of Maryland College Park, and Johns Hopkins Bloomberg School of Public Health, compared the degree of uncertainty and complexity in the field of microbiology with that of astronomy: “We have very similar problems. We see many objects with very faint signals. We have to view them from a distance. Most of what we’re looking at is unknown to science.” We know that the unexplored microbial world is huge.

What we also know, and this was a recurrent theme throughout the two-day symposium, is that microbes exist everywhere and in enormous numbers. The various presenters guided their audience, through the microbial worlds found in oceans and coral reefs, in caves and prairie marshes, in Antarctica, in Bangladesh, and within the human body. Indeed, in our co-evolutionary association with microbes there are perhaps four hundred different microbial species living in every human being. One might have been surprised to learn that we are only one part human and ten parts microbe! Dr. David Relman, Associate Professor of Medicine of Microbiology and Immunology, and Assistant Professor of Medicine at Stanford University, uses the human body as a “microbial observatory”, focusing his research on the roles that microbial communities play in oral and intestinal disease. But while some microbes make us sick, others are responsible for breaking down our food. Still others, Dr. Colwell explained, may produce compounds that influence behavior, and there is some speculation, said Dr. Susan Perkins, Assistant Curator at the Museum’s Sackler Institute for Comparative Genomics and Division of Invertebrate Zoology, that an individual’s weight may be tied to the particular microbes present in their gut. Also, we have microbes to thank for turning grapes into wine, milk into cheese, malt into beer, and making dough rise. “If you love to eat,” Dr. Perkins reminded us, “you love microbes.”

Off-white, cotton t-shirts sold at the symposium reading “Save the Microbes, Save the World!” served as simple reminders of the symposium’s underlying theme-- that microbes are part of the huge interconnected fabric of the Earth. With this as the underlying premise, what then is the relationship between the microbial world and general habitat loss? Oceanographer Dr. Patricia Glibert talked about the global proliferation of Harmful Algal Blooms (HAB’s) caused by such factors as population increase, the industrialization of world meat production, nitrogen and phosphorous fertilizers and climate change. Dr. Kurt Reinhart, Professor of Biology at the University of Indiana, discussed plant-microbe interactions in native versus non-native ranges. Dr. Forest Rohwer, Assistant Professor of Biology at San Diego State University, focused on viruses, microbes, and the decline of coral reefs.

Most types of habitat loss directly and dangerously affect humans. For a couple of more obvious examples, Richard Ostfeld, Senior Scientist at the Institute of Ecosystem Studies, discussed his work on pathogen transmission, and his discovery of a strong negative correlation between bird species diversity, and human West Nile Virus incidents and Dr. Rita Colwell discussed her work building predictive models of cholera outbreaks, and the relationship of these outbreaks to climate driven factors such as sea surface temperature, sea surface height, and salinity. The good news, as explained by Dr. Peter Groffman, Senior Scientist at the Institute of Ecosystem Studies in Millbrook, New York, is that microbes carry out many positive geochemical processes in the environment, including the production of food and fiber, the degradation of organic matter, and the consumption of pollutants like DDT and PCB’s, all of which help keep our planet safe.

At the end of the two-day symposium, scientists agreed on two critical points. First, if Earth is a living, breathing system, with all organisms connected in complex ways, then we must expand our thinking about biodiversity to include not just charismatic megafauna but the trillions of microbes that make up 90% of the Earth’s biomass. In the words of Dr. Rita Colwell, “The sustainability of this wonderful blue planet rests unmistakably and irrevocably on the vast microbial diversity that we are appreciating and hopefully better understanding through this meeting.” Second, scientists agreed that along with protecting biodiversity comes the need for better communication about the multiplicity of roles played by microbes in the universe, not just amongst themselves---with their many and diverse areas of expertise—but between the scientific community and the public at large. As Dr. Perkins remarked, “the relationship between our knowledge of microbes and our ability to engage in effective conservation efforts is likely to be the most important emerging area in conservation biology.”
Leaving the symposium through the imposing Hall of Northwest Coast Indians, past the haunting Nootka ceremonial dance masks and intricate Kwakiutl basketry, one might well have been absorbed in the over powering and inescapable truth that microbes are responsible for all life as we know it.

Submitted by, Susan C. Scheuer