Bacteria Form Living Cables in Polymer Solutions, Revealing New Insights for Medicine and Industry

Q&A Forum

Bacteria Form Living Cables in Polymer Solutions, Revealing New Insights for Medicine and Industry

Asked by terryaster at 1:20pm on Jan 21 2025

Scientists from Caltech and Princeton University have discovered that bacterial cells growing in polymer-rich solutions, such as mucus, form long, cable-like structures that buckle and twist into an interconnected "living gel." This finding sheds light on bacterial behavior in polymeric environments and could inform research on diseases like cystic fibrosis and biofilm formation.

The study, published on January 17 in Science Advances, highlights the potential impact on treating conditions like cystic fibrosis, where thickened mucus in the lungs fosters life-threatening bacterial infections. The findings also extend to biofilms, polymer-secreting bacterial colonies that appear in nature and industrial settings, often causing equipment malfunctions and health risks.

"When bacteria grow in fluids containing spaghetti-like molecules called polymers—such as mucus—they form cable-like structures that behave like living gels," explained Sujit Datta, a Caltech professor of chemical engineering, bioengineering, and biophysics, and the study's corresponding author. Datta noted similarities between these living structures and the physics of nonliving gels like Jell-O or Purell.

Sebastian Gonzalez La Corte, the study's lead author and a graduate student under Datta at Princeton University, focused on how the higher polymer concentration in mucus affects bacterial growth, particularly in cystic fibrosis patients. Using mucus samples provided by MIT, Gonzalez La Corte grew E. coli in regular liquids and cystic fibrosis-like polymeric solutions, observing under a microscope how the cells behaved in each case.

In typical conditions, bacterial cells separate after division. However, in polymeric solutions, cells remained stuck end to end, forming long, cable-like structures. "As cells keep dividing and sticking together, they form these intricate, elongated cables that eventually bend and tangle into networks," said Gonzalez La Corte.

These bacterial cables continued growing as long as nutrients were available, with chains stretching thousands of cells long. Further experiments revealed that the phenomenon occurred across bacterial species and various polymer types, including synthetic ones.

Although inspired by cystic fibrosis research, the findings have broader implications. Mucus plays a vital role not only in the lungs but also in the gut and cervicovaginal tract. Additionally, the study provides insights into biofilms, bacterial colonies embedded in a polymer matrix. Biofilms, such as dental plaque or soil bacteria, are notoriously resistant to antibiotics and difficult to remove from surfaces, posing challenges in both healthcare and industry.

"The polymer matrix biofilms secrete makes them resilient to treatments," Datta explained. "Understanding how cells grow within that matrix could be crucial for finding better ways to control biofilms."

The team determined that external pressure from surrounding polymers forces dividing bacterial cells together, creating the cables. This process is governed by a physical phenomenon called depletion interaction, where outside pressure generates attractive forces between objects. Using depletion interaction theory, Gonzalez La Corte developed a model to predict bacterial cable growth in polymeric environments.

"We can now apply established polymer physics theories, originally developed for non-biological systems, to predict when these cables will form in biological contexts," Datta said. The findings not only advance fundamental understanding of bacterial behavior but also open new avenues for medical and industrial applications.

Brick + Beam Detroit

Q&A Forum