When UC Berkeley postdoctoral fellow Morgan Delarue measured the force the growing mass of cells exerted as they pushed against one another, he calculated that it can be nearly five times higher than the pressure in a car tire — about 150 psi, or 10 times atmospheric pressure.
This is more than just a weird observation, said Oskar Hallatschek, a UC Berkeley assistant professor of physics and leader of the team. Budding yeast or other living cells, which split in two and grow exponentially in number, may well generate such mechanical forces to alter their environment, possibly in damaging ways. This may be even more important for cells like yeast that cannot move.
“Our results suggest that self-driven jamming and the build up of large pressures is a natural tendency of proliferating cells, and may be contributing to microbial pathogenesis and biofouling,” he said. Biofouling is when bacteria or other organisms grow so prolifically as to interfere with the operation of machinery, such as happens in water pumps.
In fact, when graduate student Jörn Hartung grew yeast in a gel, he found that they split the gel, a possible example of how they could create cracks in rocks or soil particles.
“The mechanism that allows these populations of cells to generate such forces could be relevant to remodeling the microenvironment,” said Hallatschek, who is a member of the California Institute for Quantitative Biosciences (QB3). “If you are constrained, maybe it’s good to be able to break the material and change the pore’s sizes in the environment.”