Despite the small population of each rare species in a microbial community, such species may number as much as several hundred within a community, such that the so-called "rare biosphere" may account for roughly 20-30 percent of individual bacteria within an aquatic community. The sheer numbers of rare species result in the rare biosphere containing a large reservoir of genes that can degrade important organic pollutants, and that could help the entire microbial community maintain stability in the face of changing conditions, possibly including climate change.
To investigate this issue a team from Georgia Institute of Technology, Atlanta, established "mesocosms" -- indoor experimental systems -- containing 20 liters of water, each. They inoculated these with water samples from the nearby freshwater Lake Lanier.
The motivation for the study was to be able to better predict how microbial communities will respond to future perturbations such as pesticides, oil spills, and even climate change, said Konstantinidis. Questions it might help answer include that of how valuable microbial diversity is for ecosystem functioning, including for maintaining resilience to human-caused pollution. The results of this and future studies might also help enable predicting the consequences of loss of biodiversity, for example, in the wake of massive pollutant spills or climate change.
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Posted by Dr. Tim Sandle