How can a large number of cells be concentrated?

Centrifugation is a process that utilizes the centrifugal force generated by a spinning motion to separate components of different densities within a liquid. When applied to a culture of cells, centrifugation accelerates the settling of cells to the bottom of the container, allowing for the concentration of cells. As the liquid is spun, denser particles, such as cells, will move toward the bottom, forming a pellet. The supernatant, which is the liquid above the pellet, can then be removed to leave behind a concentrated solution of cells.

This method is particularly effective for concentrating a large number of cells quickly and efficiently without adversely affecting their viability. Other methods, such as adding more nutrients, do not inherently increase the cellular concentration and might only support cell growth over time rather than providing an immediate concentration effect. Diluting with water would actually decrease the concentration of cells, while heating the culture could harm or kill the cells, making them less viable. Thus, centrifugation stands out as the most suitable approach for concentrating a large number of cells.