Attack of the cannibalistic bacteria

When the going gets tough, watch out for Bacillus subtilis. The green rods in this micrograph are living members of this bacterial species that have killed nearby B. subtilis members (red rods) for food. Like many soil-dwelling bacteria, B. subtilis forms a hardy spore when confronted with rough conditions. Before irreversibly committing to sporulation, however, some of these microbes secrete two proteins, Richard Losick of Harvard University and his colleagues report in an upcoming Science. One protein delays sporulation in adjacent B. subtilis members, and the second bursts the neighbors, liberating nutrients from them. This cannibalistic behavior is unusual. “It came as a big surprise because here the bacterium is making an antibiotic to kill its own siblings,” says Losick. “It’s fratricide.”

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