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One of the greatest joys of being a scientist is continuously having the opportunity to see the world in new ways. At a national laboratory or research university, you’re exposed to many different fields of research, from which you can always glean something useful. My current fascination is learning about microbial communities and how they thrive by achieving just the right balance between cooperation and competition.
My training is in biochemistry and cell biology, but I was exposed to medical microbiology during a stint as a faculty member in a medical school. There my view of microbes was tainted by the perspective of my colleagues, who saw them either as pathogens or as opportunistic organisms that contaminated tissue-culture plates. My view of cell communities, conversely, came from my research in cancer biology, where I saw the cooperative cell assemblies of normal tissues as driven by genetic programming. Without this enforced cooperation, cells would become selfish, dooming the organism to death by cancer.
This was a simplistic view, based on the idea that natural selection only operates at the level of the individual. A more nuanced appreciation of evolutionary theory reveals that a behavior such as altruism can benefit genetic lineages even when it does so at the expense of the individual. Still, my bias remained that cooperation was something genetically encoded. Then I learned about microbial communities and what they can teach us about thriving within constraints.
Numerically and by biomass, bacteria are the most successful organisms on Earth. Much of this success is due to their small size and relative simplicity, which allows for fast reproduction and correspondingly rapid evolution. But the price of small size and rapid growth is having a small genome, which constrains the diversity of metabolic functions that a single microbe can have. Thus, bacteria tend to be specialized for using just a few substrates. So how can simple bacteria thrive in a complex environment? By cooperating—a cooperation driven by need.
Bacteria rarely live in a given ecological niche by themselves. Instead, they exist in communities in which one bacterial species generates as waste the substrates another species needs to survive. Their waste products are used, in turn, by other bacterial species in a complex food chain. Survival requires balancing the needs of the individual with the well-being of the group, both within and across species. How this balancing act is orchestrated can be fascinating to explore as the relative roles of cooperation, opportunism, parasitism and competition change with alterations in available resources.
The dynamics of microbial behavior are not just a great demonstration of how the laws of natural selection work and how they depend on the nature of both selective pressures and environmental constraints. Microbial communities also demonstrate important nongenetic principles of cooperation. And herein lie lessons that scientists can emulate.
To be successful, scientists must be able to compete not only for funding, but for important research topics that will give them visibility and attract good students. In the earlier days of biology, questions were more general, making it easier to keep up with broad fields and to exploit novel research findings as they arose. As the nature of our work has become more complex and the amount of biological information has exploded, we have necessarily become more specialized. There is only so much information each of us can handle.
With specialization has come an increasing dependence on other specialized biologists to provide us with needed data and to support our submitted papers and grants. At the same time, resources have become scarcer, and we find ourselves competing with the same scientists on whom we are becoming dependent. Thus, it is necessary to find a balance between cooperation and competition in order to survive, and perhaps even to thrive.
The composition of microbial communities is driven by both the interaction of different species and external environmental factors that determine resource availability. Scientists want to learn the rules governing these complex relationships so they can reengineer bacterial communities for the production of useful substances, or for bioremediation. Perhaps as we learn the optimal strategies that microbial communities use to work together effectively, we will gain insights into how we can better work together as a community of scientists.
H. Steven Wiley is lead biologist for the Environmental Molecular Sciences Laboratory at Pacific Northwest National Laboratory.