The spiral-shaped bacteria Helicobacter pylori are common and troublesome.
More than 13 percent of Americans have an H. pylori infection, although rates vary with age, race, and socioeconomic status. The microorganism uses its corkscrew-like tail to power forwards through viscous fluids such as stomach mucus. When it arrives at the epithelium of the stomach wall, it can cause everything from ulcers to cancer.
In a new study published by Physical Review Letters, FAMU-FSU College of Engineering researchers created a 3D model of this bacterium to better understand its movement, hoping to crack the code governing the organism’s motility and develop alternative treatments for infections, such as strengthening the gastric mucus barrier that stands against the bacterium.
Study co-author Hadi Mohammadigoushki, an associate professor in the Department of Chemical and Biomedical Engineering, said that people around the world have treated ulcers with antibiotics because antibiotics kill bacteria, but it’s a double-edged sword. He said that if they understand how these bacteria move, they can work towards providing other solutions for treatment.
In the experiments, the team placed a model of the bacterium in a high-viscosity polymer gel, an example of what’s called a yield-stress fluid. Those fluids behave as solids under small stresses but flow like liquids beyond a critical stress point.
Then they used a magnetic field to rotate the 3D model, mimicking the behaviour of the microorganism. Using particle tracking and imaging techniques, the researchers measured the speed of the bacterium and visualised the distribution and density of the fluid flowing around it.
The researchers identified two critical thresholds that the bacterium must overcome: the torque needed to rotate the swimming model and the force needed to propel the model forwards.
Mohammadigoushki said that they found that if the tail propulsion was too weak, the bacterium remains stuck in the gel. He added that if the force was strong enough it could penetrate the gel. He compared the bacterium to a drill, saying that if the drill isn’t strong enough and you are not pushing the screw with enough force, it won’t penetrate the wall, but with the right amount of force, it can break through.
The swimming motions and force that allow H. pylori to move also apply to larger objects, such as earthworms that burrow in the soil, various parasites, and more.
Kourosh Shoele, an assistant professor in the Department of Mechanical Engineering, said that if they understand how the bacterium successfully moves to attack our body, they can use that information for whatever they can imagine. He explained how learning from nature can get a better response from mechanical and biological systems.
Shoele said that in the future, they can design a micro-robot that can deliver a drug to a particular location in the body, in terms of fighting leukaemia and other diseases. He added that they can also design tiny robots that use swimming motion and force, like H. pylori, that can dig deep in the sand to explore for water or oil. He said that the possibilities are endless.
Farshad Nazari, an FSU doctoral student in chemical and biomedical engineering, is working with the two researchers and is the leading author of this paper.
