TRAVELING TOGETHER: A Paenibacillus vortex colony, 8 cm in diameter. The bright dots are dense groups of bacteria, termed vortices, that swarm collectively around a common center. As the cells replicate, the vortex expands and moves outward as a unit, leaving behind a trail of older, nonreplicating cells, which compose the branches. The leading vortices send signals to prompt the cells in the branches to generate new, fast moving vortices that become new leaders. (Color added; yellow indicates high cell density, red indicates low cell density.)COURTESY OF ESCHEL BEN-JACOB/INA BRAINISEver since Antonie van Leeuwenhoek espied the cavorting, swiftly swimming tiny critters he called animalcules through a small sphere of glass held in a metal frame, microscopes have figured into microbiological advances.
The stunning diversity of microbes, whether harvested from the human gut or scraped from the ocean floor, has increasingly led researchers to explore microbial behavior. As research entered the age of DNA, microscopes fell out of favor, and gaps in understanding the twitching, swimming, or creeping movements of microbes individually and as a colony have persisted.
Studying bacterial behavior requires techniques to view, track, and analyze these organisms in motion. Today, this involves new tools, such as genetically encoded fluorescent reporters, and improvements on old ones, such as quantitative methods for analyzing the complex swirls and spirals of bacterial colonies growing on agar plates. Even microscopes have made a comeback over the past two decades, thanks to the advent of small, relatively inexpensive cameras and ...
