Flouting the scientific canon that all bacteria are microscopic, researchers have discovered a strain so huge that it can be seen with the naked eye.
The single-celled organism, plucked from the bowels of an Australian fish, is about the size of a hyphen in a newspaper, making it by far the largest bacterium ever detected.
In measuring more than one-fiftieth of an inch in length and possessing a volume a million times that of the common E. coli microbe, the newly discovered bacterium seems to defy laws of biology that limit how big a simple bacterial cell can grow.
So outsized is the creature that researchers may soon be able to use it to begin exploring the intimate details of bacterial innards, a task impossible with the tinier species of microbes.
"It's so huge that we could stick electrodes into it," said Esther R. Angert of Indiana University in Bloomington. "There's a world of cell physiology that could be done with this thing."
The researcher, who is finishing her doctorate in the laboratory of Dr. Norman Pace, performed the experiments that demonstrated the bacterial nature of the beast.
She showed that despite its extraordinary dimensions, the organism's genes bore all the earmarks of a bacterium.
The report of the giant bacterium, called Epulopiscium fishelsoni, appears today in the British journal Nature.
Commanding though the bacterium is, it may not be the world's largest.
Realizing that bacteria have the ability to grow beyond boundaries previously set for them, scientists may well find larger ones.