For This Microbe, Cousins Not Particularly Welcome
A bacterial species that depends on cooperation to survive is discriminating when it comes to the company it keeps.
Scientists from Indiana University Bloomington and Netherlands' Centre for Terrestrial Ecology have learned Myxococcus xanthus cells are able to recognize genetic differences in one another that are so subtle, even the scientists studying them must go to great lengths to tell them apart.
The scientists' report, which appears in a recent issue of Current Biology, also provides further evidence that cooperation in nature is not always a festival of peace and love. Rather, cooperation may be more of a grudging necessity, in which partners continually compete and undermine one another in a bid for evolutionary dominance.
"In some social microbes, cooperation is something that happens primarily among identical or very similar cells, as a way of competing against relatively unrelated individuals in other cooperative units," said IU Bloomington biologist Gregory Velicer, who led the research.
"This is unlike humans, who are more likely to cooperate with unrelated individuals as well as with close kin. In the bacteria we study, cooperation appears to be highly restricted."
Myxococcus xanthus is a predatory bacterium that swarms through soil, killing and eating other microbes by secreting toxic and digestive compounds. When food runs out, cells aggregate and exchange chemical signals to form cooperative, multi-cellular "fruiting bodies." Some of the cells create the fruiting body's structure, while other cells are destined to become hardy spores for the purpose of surviving difficult conditions.
"Upon starvation, groups of up to 100,000 cells of the social bacterium Myxococcus xanthus cooperate to build spore-bearing fruiting bodies (green, false color). A fruiting body is shown growing on an agar surface (brown). (Credit: Supriya Kadam and Juergen Berger, Max Planck Institute)"
Source: Indiana University
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