MAR 25, 2020 9:30 PM PDT

The Patterns Formed by Biofilms

WRITTEN BY: Carmen Leitch

Bacterial cells grow in colonies called biofilms, which take on new characteristics. For example, a biofilm of bacteria is much tougher to destroy than individual bacterial cells. Researchers at Princeton University have now captured the formation of intricate patterns as these colonies grow, and learned more about the physical forces behind them. The findings, which have been reported in the Proceedings of the National Academy of Sciences, may also help us gain new insights into the development of human tissues.

screenshot from eLife 2019;8:e43920 DOI: 10.7554/eLife.43920 / Biofilm growth of Vibrio cholerae bacteria on a stiff substrate / Credit: Princeton Engineering

"This adds to a body of work coming from a mechanical perspective that says what we're seeing is the playing out of physical laws," said study co-author Ned Wingreen, the Howard A. Prior Professor in the Life Sciences and a professor of molecular biology and the Lewis-Sigler Institute for Integrative Genomics. "It will help us understand to what extent some of these patterns influence the biofilm properties that are important biologically and medically."

Researchers with expertise in different areas like mechanical engineering and mathematical modeling collaborated on this study. They analyzed how a bacterium that can cause the disease cholera, Vibrio cholerae, forms biofilms. At first, it generates a flat layer on a soft substrate, but then the biofilm starts to wrinkle and form peaks and valleys, zigzags and radial patterns. The patterns that are made by the biofilm depend on how stiff or soft the substrate it grows on is, which can be altered by varying the amount of agar that went into making it. They also depend on how the biofilm absorbs nutrients from the substrate; as they are depleted, uneven growth patterns form.  

"This is a very complicated process involving growth and mechanics," said lead author Chenyi Fei, a graduate student in the Lewis-Sigler Institute. "To understand it, we built what we call a chemo-mechanical model. We take into account the nutrients and the nonuniform growth of the biofilm, and how those features translate into the mechanical forces or stresses that accumulate."

The scientists were able to predict where and when the biofilm would get stressed, which also predicted where wrinkles appeared. Mechanical instability modeling plays into this work, though it has previously been used to study problems like how extreme temperatures cause stress on railroad tracks.

"In the previous century, mechanical instabilities were being studied with a focus on trying to prevent failure mechanisms in structures," explained co-author Sheng Mao, a former postdoctoral researcher at Princeton who is now an assistant professor at Peking University. "But in a new wave of studies, we are trying to exploit these mechanical instabilities to make tunable structures for various purposes," like synthetic materials that might one day be used to repair injuries, or engineered tissues that treat disease.

Sources: AAAS/Eurekalert! via Princeton University, Engineering School, Proceedings of the National Academy of Sciences

About the Author
  • Experienced research scientist and technical expert with authorships on over 30 peer-reviewed publications, traveler to over 70 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
JAN 10, 2021
Microbiology
Some Bacteria Know the Time
JAN 10, 2021
Some Bacteria Know the Time
People, animals, and even plants are known to have biological clocks, and new work has revealed that free-living bacteri ...
FEB 07, 2021
Microbiology
Positive Results From A Clinical Trial of an HIV Vaccine
FEB 07, 2021
Positive Results From A Clinical Trial of an HIV Vaccine
After years of effort, researchers are reporting that there were encouraging results from a phase 1 clinical trial which ...
MAR 03, 2021
Microbiology
Study May Explain Higher Flu Risk in Adults That Were Premature Babies
MAR 03, 2021
Study May Explain Higher Flu Risk in Adults That Were Premature Babies
Medical treatments for the care of premature babies have allowed many individuals to get through that challenge and lead ...
MAR 16, 2021
Immunology
What Happens When Your Immune System Forgets
MAR 16, 2021
What Happens When Your Immune System Forgets
One of the most remarkable features of the immune system is its ability to “remember” past encounters with p ...
MAR 18, 2021
Microbiology
How to Avoid Greenwashing Your Lab
MAR 18, 2021
How to Avoid Greenwashing Your Lab
Greenwashing is a term used to describe an intentionally-misleading or false claim about the environmental benefits of a ...
APR 04, 2021
Cell & Molecular Biology
Human Malaria Trial Creates More Questions
APR 04, 2021
Human Malaria Trial Creates More Questions
Malaria is a major health problem in many parts of the world; nearly half a million people die from malaria, and another ...
Loading Comments...