Sibling rivalry can be intense, as anyone who grew up with one or more brothers or sisters knows.
However, among a certain bacterial species, sibling colonies take competition to a deadly level, researchers report in The Proceedings of the National Academy of Sciences. Avraham Be'er and Harry L. Swinney of the University of Texas studied colonies of Paenibacillus dendritiformis, which when started as a single droplet grow outward, forming intricate bush-like branches. Using samples from the same bacterial culture (and thus "siblings"), the researchers started two colonies a given distance apart on the agar. After nine hours, the colonies started growing outward. But at 40 hours, the facing fronts of both colonies started to slow down. According to researchers, the colonies were secreting a growth-inhibiting compound, one that was killing the bacteria along the facing fronts.
New York Times