Microbial Symbiosis: In Sickness and in Health

摘要

In this special issue, we explore the theme of symbiosis between eukaryotic hosts and their microbial associates. These invited contributions describe results of studies reported at the recent ASM Beneficial Microbes Conference, held in October 2008 in San Diego, CA. The core principle governing symbiotic interactions is adaptation, in both senses of the word--adaptation in the individual's lifetime, typically involving changes in the molecular biology and biochemistry of the cells, and adaptation in the evolutionary sense, involving selection for populations that differ genetically from those that preceded them. The short generation time for most bacteria can make the distinction between adaptation of the individual and the population challenging to distinguish. One of the hallmarks of the lives of symbiotic bacteria is the diversity of environments to which they must adapt. The physiology of the host changes during its lifetime, populations of genetically variable hosts present a challenging array of conditions, and the other microorganisms in the symbiotic niche shape and change the environment. Therefore, symbiotic microbes must be nimble and flexible in their responses to ensure adaptation of individuals and populations to the vagaries of their world. In this issue, our authors explore many levels of adaptation in a fascinating array of symbiotic systems.