Eshel Ben-Jacob is interested not only in the genomes of the bacteria he studies but also in their personalities. He compares many to Hollywood celebrities. “On the one hand, we admire them, but on the other hand, we think that they are stupid,” says Ben-Jacob, a professor of physics at Tel Aviv University in Israel. In December, though, he and his colleagues published a paper in the journal BMC Genomics reporting that a species of soil bacteria he discovered in the mid-1990s, Paenibacillus vortex, is surprisingly smart by microbial standards.
The team identified this relative intelligence by comparing the P. vortex genome with that of 502 different bacterial species whose genomes were known and, based on that comparison, calculating what Ben-Jacob calls the bugs’ “social IQ score.” The researchers counted genes associated with social function, such as those allowing bacteria to communicate and process environmental information and to synthesize chemicals that are useful when competing with other organisms. P. vortex and two other Paenibacillus strains have more of those genes than any of the other 499 bacteria Ben-Jacob studied, including pathogenic bacteria such as Escherichia coli, indicating a capacity for “exceptionally brilliant social skills.”
This social sophistication is manifested in the elaborate colonies that P. vortex can form, such as the one in the accompanying micrograph, which grew over several days in a petri dish. The colony, about eight centimeters in diameter, contains 100 times more bacteria than the number of people on earth. The blue dots are dense groups of bacteria called vortices that swarm collectively around a common center to better pave the way on hard surfaces and protect themselves from hazards. As the cells replicate, each vortex expands in size and moves outward as a unit, leaving behind a trail of older, nonreplicating cells, which form branches that maintain communication across the colony.
“Acting jointly, these tiny organisms can sense the environment, process information, solve problems and make decisions so as to thrive in harsh environments,” Ben-Jacob says. Never underestimate a single-celled star.