Bacteria take turns to feed when living under scarcity

In-phase oscillations in a pair of biofilms grown in the same microfluidic chamber - UPF-UCSDTimesharing, researchers have found, isn't only for vacation properties.  While the idea of splitting getaway condos in exotic destinations among various owners has been popular in real estate for decades, biologists at University of California San Diego and at UPF have discovered that communities of bacteria have been employing a similar strategy for millions of years.

The team, which included UPF professor Jordi García-Ojalvo, asked what neighbouring communities of bacteria might do when food becomes scarce. The researchers found that bacteria faced with limited nutrients will enter an elegant timesharing strategy in which communities alternate feeding periods to maximize efficiency in consumption. The study will be published April 6 in journal Science.

"What's interesting here is that you have these simple, single-celled bacteria that are tiny and seem to be lonely creatures, but in a community, they start to exhibit very dynamic and complex behaviors you would attribute to more sophisticated organisms or a social network," says Gürol Süel, associate director of the San Diego Center for Systems Biology. "It's the same timesharing concept used in computer science, vacation homes, and a lot of social applications."

In 2015, Süel, García-Ojalvo and their colleagues discovered that structured communities of bacteria, or "biofilms," communicate with each other through electrical pulses in the same way as our brain cells. The new study investigates how two biofilm communities interact. Through mathematical models and experiments using microfluidic techniques and time-lapse microscopy, the researchers found that nearby biofilm communities will engage in synchronized behaviors through these electrical signals.

The experiments revealed that when biofilms faced scenarios of limited amounts of nutrients, they began to alternate their feeding periods to reduce competition and avoid "traffic jams" of consumption. "It is common for living systems to operate in unison, but here we're showing that working out-of-sync can also provide a biological benefit", says Garcia-Ojalvo, professor of systems b iology at UPF.

"These bacteria are just about everywhere-from your teeth to soil to drain pipes. It's interesting to think that these simple organisms two billion years ago developed the same timesharing strategy that we humans are now using for all kinds of purposes," concludes Süel.


Scarcity situation. Time-lapse movie of anti-phase oscillations in a pair of Bacillus subtilis biofilms. The images show the edge of two biofilms grown in the same microfluidic chamber. Cyan indicates fluorescence from the membrane potential dye Thioflavin T. The time-traces show fluorescence from the corresponding biofilms. (UPF-UCSD)

Coauthors on the paper include Jintao Liu, Daisy Lee, and Joseph Larkin of UC San Diego's Division of Biological Sciences, and Rosa Martinez-Corral and Marçal Gabalda-Sagarrafrom Pompeu Fabra University.

The study was supported by the San Diego Center for Systems Biology, the National Science Foundation, National Institute of General Medical Sciences, the Defense Advanced Research Projects Agency, the Howard Hughes Medical Institute - Simons Foundation Faculty Scholars program, a Simons Foundation Fellowship of the Helen Hay Whitney Foundation, a Career Award at the Scientific Interface from the Burroughs Wellcome Fund, the Spanish Ministry of Economy and Competitiveness (MINECO, Spain) and FEDER, the Generalitat de Catalunya, the ICREA Academia program, the "Maria de Maeztu" Program for Units of Excellence in Research and Development (Spanish Ministry of Economy and Competitiveness), "la Caixa" Foundation, and the Spanish Ministry of Education, Culture and Sports (Spain).


Reference work: Jintao Liu, Rosa Martinez-Corral, Arthur Prindle, Dong-yeon D. Lee, Joseph Larkin, Marçal, Gabalda-Sagarra, Jordi Garcia-Ojalvo and Gürol M. Süel. Coupling between distant biofilms and emergence of nutrient time-sharing. Science, April 2017.


Picture 1: Image of two Bacillus subtilis biofilms grown in the same microfluidic chamber. Cyan indicates fluorescence from the membrane potential dye Thioflavin T. (UPF-UCSD)