“Sometimes they just pop wheelies and stand up.” — GERARD WONG
Sure, but can they chew gum too?
By Tina Hesman Saey
Jokes that open with a bacterium walking into a bar just got
a little less farfetched.
Some bacteria can stand up
and toddle away on tiny legs, a
new study shows. The finding,
reported in the Oct. 8 Science,
could help scientists better
understand how some bacteria
form dense antibiotic-resistant
communities called biofilms
and may lead to better ways to
combat such microbes.
Researchers had already documented bacteria swimming
through liquids or crawling on their bel-lies, but no one had ever seen bacteria get
up and walk until a group of undergraduate students at the University of Illinois
at Urbana-Champaign made videos of
Pseudomonas aeruginosa bacteria on a
microscope slide. Working under the
supervision of Gerard Wong, a biophysicist now at UCLA, the students adapted
a technique used by physicists to track
microscopic particles. Computer pro-
Some bacteria can stand on end and use thin
appendages called pili to stroll across a surface.
grams allowed the researchers to quickly
sort through footage of teeming bacteria.
“My students started seeing all this neat
stuff,” Wong says. “They’d tell me, ‘ Yeah,
sometimes they just pop wheelies and
stand up.’ ”
The bacteria’s unsteady walks require
the use of hairlike appendages called
Type IV pili, the team found. These
stringy “legs” were already known to
be used for twitching motility, a type of
locomotion in which pili at one end of a
bacterium pull the cell across a surface.
“It’s almost like front wheel drive,” Wong
says. These crawling bacteria move in
relatively straight lines over fairly long
distances—an average of six micro-
meters — possibly enabling the microbes
to move toward chemical attractants.
Microbes do the
Bacteria conduct electricity
through a network of fibers
By Marissa Cevallos
Just as a household wire carries electrons from wall socket to appliance,
bacteria can conduct electricity along tiny
wirelike appendages, researchers report
online October 11 in the Proceedings
of the National Academy of Sciences.
A community of bacteria connected by
gangly nanowires could act as a slimy fuel
cell, digesting organic matter and churning out electricity.
Researchers noticed that deep-sea bacteria grew the curious wires when placed
in environments with little oxygen.
Rather than suffocate, the microbes grew
protein nanowires to hunt for pockets of
oxygen or other elements, says microbiologist Yuri Gorby of the J. Craig Venter
Institute in San Diego. Then the bacteria
appeared to share electrons — their way
of breathing — by connecting their wires.
“We’ve only known about electricity for
200 years, but we’re hypothesizing they’ve
been doing it for billions of years,” Gorby
says. The scientists had suspected that
bacterial nanowires carry electrons, but
struggled to create instruments that could
measure the current without destroying
the fragile conduits. Using nanotech tools,
researchers led by Mohamed El-Naggar
of the University of Southern California
in Los Angeles found that wired-up com-
munities of Shewanella bacteria can act