Bacteria are more gregarious than previously thought. Not only do they routinely
engage in small talk among themselves, but research is showing that many are
also multilingual and can communicate with members of other species.
"When we think about bacteria, we think about them as being tiny single-celled
organisms that live these very asocial reclusive lives," said Bonnie Bassler,
a molecular biologist at Princeton University. "In fact, bacteria have
developed language, and the language is chemical."
Speaking at the annual meeting for the American Association for the Advancement
of Science earlier this year in Washington, Bassler explained that in addition
to being able to communicate with members of their own species, many bacteria
can also talk to members of other species using a universal chemical language.

Gathering a quorum

Bacteria are able to communicate with one another through a process known as
quorum sensing.
Here's how it works: Individual bacteria secrete signaling molecules called
autoinducers into their environments, and as the number of bacteria in a colony
increases, so does the concentration of the signaling molecule.

Bioglyphs Secrets Unveiled

With lights turned on,
the secret behind Bioglyphs paintings is revealed -- petri dishes
coated with agar support colonies of bioluminescent bacteria. Montana
State University-Bozeman School of Art student Angela Bowlds created
this piece. Bioglyphs--an exhibition of living bioluminescent
paintings--brings science and art together in the form of a
collaborative project involving students from the MSU School of Art,
and science and engineering students from MSU’s Center for Biofilm
Engineering (CBE). For more information about the project, visit the Bioglyphs website Click to enlarge.








Once a critical mass, or
quorum, of bacteria and auto inducers are reached, specific behaviors can be
initiated.
Quorum sensing allows bacteria to coordinate their behaviors on a global scale
and to act like enormous multicellular organisms, Bassler explained. The types
of behaviors initiated by quorum sensing are typically those that are beneficial
only when performed as a group, such as the release of toxins or the formation
of aggregates called biofilms.
"The goal of quorum sensing is to count," Bassler said. Bacteria
in the wild are not typically found in homogenous groups, but rather coexist
in diverse communities with other bacterial species. "We don't think anymore
that it does bacteria any good to only count its own species; they have to be
able to take a census of the rest of the population."
One way they do this is through quorum sensing. In addition to autoinducers
that are species-specific, many bacteria also produce a universal autoinducer,
known as AI-2, which can be understood across different bacterial species.
AI-2 was first discovered in a bioluminescent species of marine bacteria capable
of giving off visible light, but it has since been identified in hundreds of
other species. "This is a generic language," said Bassler. "It's
the trade language that says 'other.'"
Applications
Many scientists believe the discovery of AI-2 could lead to the development
of a new class of antibiotics.
"If we could keep the bacteria from talking or listening, we might be
able to develop new kinds of therapeutics," Bassler said.
Because such a drug would not kill the bacteria directly, but only disrupt
their activity and prevent them from releasing their toxins, it would not encourage
the development of resistance--a problem that is plaguing many current antibiotics.
Bassler believes there are probably other molecules like AI-2.
"There are probably many more molecules to be found that tells who the
other guy is as well," she said. "We're only at the beginning of this
field."

Image at top of page: Credit: ©Whitehead Institute for
Biomedical Research