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Bacteria and their viruses (phages) undergo rapid coevolution in test tubes, but the relevance to natural environments is unclear. By using a "mark-recapture" approach, we showed rapid coevolution of bacteria and phages in a soil community. Unlike coevolution in vitro, which is characterized by increases in infectivity and resistance through time (arms race dynamics), coevolution in soil resulted in hosts more resistant to their contemporary than past and future parasites (fluctuating selection dynamics). Fluctuating selection dynamics, which can potentially continue indefinitely, can be explained by fitness costs constraining the evolution of high levels of resistance in soil. These results suggest that rapid coevolution between bacteria and phage is likely to play a key role in structuring natural microbial communities. [ABSTRACT FROM AUTHOR]

The article examines roles that biomedicines play in microbial populations. While it was once assumed that natural antibiotics were microbe-killers produced by soil-dwelling fungi and bacteria, it is now believed that these molecules may serve as tools for communication or aid in microbial metabolism. Knowledge of this subject is largely due to research conducted by Roberto Kolter of the Harvard Medical School and Julian Davies of the University of British Columbia. Kolter’s studies of the drug nystatin, a molecule with potent antifungal properties isolated from a soil bacterium, are examined. Also discussed is the history of antibiotics, beginning with the research of Nobel Prize-winning organic chemist Selman Waksman.

Microorganisms have critical roles in the functioning of soil in nutrient cycling, structural formation, and plant interactions, both positive and negative. These roles are important in reestablishing function and biodiversity in ecosystem restoration. Measurement of the community indicates the status of the system in relation to restoration targets and the effectiveness of management interventions, and manipulation of the community shows promise in the enhancement of the rate of recovery of degraded systems. [ABSTRACT FROM AUTHOR]