Carrie Arnold writes:

Close your eyes and imagine bacteria. Perhaps you’re picturing our intestinal Escherichia coli, or the shiny golden balls of staphylococcus, or the corkscrewing ringlets of Lyme disease spirochetes. Regardless of the species and its shape, chances are your mind’s eye conjured up a single cell, or maybe several free-living cells.

The problem with this image, says the microbiologist Julia Schwartzman, is that it doesn’t reflect how most bacteria are likely to live. Often, bacteria use sticky molecules to anchor themselves to a surface, growing in large, stable collectives called biofilms. The plaque on your teeth is a biofilm; so too are infections on catheters, the slimy green of pond scum and the gunk clogging your bathtub drain.

But Schwartzman’s recent work, which she conducted as a postdoctoral fellow in the lab of Otto Cordero at the Massachusetts Institute of Technology, shows that even bacteria floating in the open ocean, which lack an anchoring point for forming large conglomerates, exist in multicellular forms.

“We saw these structures that were just incredible,” she said.

As Schwartzman, Cordero and their colleagues showed in their recent paper in Current Biology, these multicellular forms arose because the bacteria developed a life cycle far more complex than is usually seen in unicellular organisms. [Continue reading…]