The Science Behind the Image Contest Winners: Bacterial Networking

The BPS Art of Science Image Contest took place again this year, during the 60th Annual Meeting in Los Angeles. The winning image was submitted by Zeinab Jahed, a PhD student at the University of California, Berkeley. Jahed took some time to provide information about the image and the science it represents.

BPS_image contest_HR

The image was taken using a field emission scanning electron microscope (SEM). It shows three colonies of Staphylococcus aureus bacterial cells (false-colored in purple) each with a diameter of ~500nm.  These colonies are “networking” and connected via nano-scale strings of bacterial cells embedded within a self-produced matrix of extracellular polymeric substance (EPS). The only visual effect we added was false-coloring the bacterial cells to make them stand out from the micropost in the background.

When my colleagues and I first observed these samples under the SEM, we were quite amazed, as we had seen nothing like it before. SEM images generally look appealing as they provide a familiar and interpretable 3D reconstruction of the sample surface morphology. However, we thought the organized and symmetric arrangement of these bacterial cells at such a small scale is what made this image particularly unique. We supposed the biophysical community might appreciate it as well, and I guess we were right!

When people view this image, we hope to draw their attention to the sophisticated but highly organized world of bacterial cells at the nano and submicron scale. Bacterial cells survive surprisingly harsh conditions through networking and cross talk.

Staphylococcus aureus cells are found all around us: they colonize our nasal cavities, attach to our skin, and adhere to organic and metallic surfaces around us. Although not always infectious, this bacterium can cause nosocomial infections, and is a common cause of food borne illnesses. Most of us have heard of staph infections; you’re more likely to get a staph infection if you come into contact with a surface that has staph attached to it. With the rise of antibiotic resistant strains of these bacteria, it is becoming more important to understand the mechanisms of attachment of these strains to surfaces. Having this knowledge, we can ultimately develop new “drug-free” methods for fighting infectious diseases by inhibiting the first step of infection – that is, bacterial attachment.

Our research program is aimed at understanding the mechanisms of cell-cell and cell-surface interactions at the nano and submicron scales. One derivative of this research is designing chemical-free antibacterial surfaces that inhibit or reduce bacterial adhesion. We study the interaction of cells with surfaces containing nano and micro-topographic features.  In previous studies we showed that bacterial attachment rates are sensitive to the nanotopographic features of metallic surfaces. In the work associated with this image, we are looking at the attachment characteristics of Staphylococcus aureus on hydrophobic poly-dimethyl-siloxane (PDMS) micro-posts. The research article associated with this image is in preparation and soon to be published.

This image resulted from a collaboration between the Molecular Cell Biomechanics Laboratory at the University of California, Berkeley, and the Nanomechanics Research Institute, the Laboratory of Biopolymers and Nanomedicine, and the Surface Science and Bio-nanomaterials Laboratory at the University of Waterloo in Canada.   Other than myself, the students involved were Hamed Shahsavan, Mohit Verma, Jacob Rogowski, and Brandon Seo. The PIs involved were Mohammad Mofrad, Frank Gu, Ting Tsui and Boxin Zhao.

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