![]() There are many different stains and staining procedures used in microbiology. Contrast, however, can be improved by either using a different type of optical system, such as phase contrast or a differential interference contrast microscope, or by staining the cells (or the background) with a chromogenic dye that not only adds contrast, but gives them a color as well. Resolution is a limitation that we can’t do much about, since most bacterial cells are already near the resolution limit of most light microscopes. Two of the most important concerns are resolution and contrast. The microscope is a very important tool in microbiology, but there are limitations when it comes to using one to observe cells in general and bacterial cells in particular. A mechanical strain-dependent cell wall growth rate predicted a straightening rate consistent with what was found experimentally.Differential Staining Techniques Viewing Bacterial Cells The models and experiments were consistent with each other. Lars Renner and Sven van Teeffelen, from the Leibniz Institute of Polymer Research and the Max Bergmann Center of Biomaterials in Germany and the Institut Pasteur in France, respectively, ran the experiment with E. ![]() Then, together with the experimental groups of Drs. Wong and Amir answered this question with a theoretical model which quantitatively predicted both how the bacteria would grow to recover its straight shape and how long it would take. In the latest research, the team explored whether coupling wall growth to mechanical strain - how the bacterium was compressed or stretched - could explain the snapback and predict how fast the bacteria would straighten when released. Amir also found that the cells straightened upon further growth, an observation which was left unresolved in that paper. This suggested that cell wall growth could sense the applied bending force. coli cells snapped back to a straighter, but still bent, shape. In previous research, Amir observed that under similar bending forces bacteria become plastically deformed, meaning when the bending force was removed, E. coli cell wall under constraints that forced the bacteria to grow into the shape of a donut. Wong and senior author Ariel Amir, assistant professor in Applied Mathematics, began by modeling the mechanics of the E. Renner at the Leibniz Institute of Polymer Research and the Max Bergmann Center of Biomaterials, Dresden, Germany.) ![]() Stressed-out E.coli recovers its straight, rod-like shape over time. “We showed that the coupling of cell wall growth to mechanical strain is quantitatively consistent with how bacteria recovered their shape after being deformed in experiments.” “This research may reveal some basic principles of bacteria growth,” said Felix Wong, a graduate student at SEAS and co-first author of the paper. The research is published in Nature Microbiology. coli) may use mechanical cues to keep their shape. Paulson School of Engineering and Applied Sciences (SEAS) has found that Escherichia coli (E. Now, a team of researchers led by the Harvard John A. Since the cell wall is the target of most antibiotics, understanding how bacteria grow their cell walls may provide insight into more effective medicines. Researchers know that shape is determined by the cell wall, yet little is known about how bacteria monitor and control it. The helical shape of Helicobacter pylori, a species of bacteria which can cause ulcers, may help it penetrate tissues.īacteria have an extraordinary ability to maintain and recover their morphology even after being twisted out of shape. ![]() Shape plays an important role in how bacteria infiltrate and attack cells in the body. Colorized scanning electron micrograph of Escherichia coli, grown in culture and adhered to a cover slip (Image courtesy of the NIH)īacteria come in all shapes and sizes - some are straight as a rod, others twist like a corkscrew.
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