Yes, filtration is a standard and effective method used to sterilize media, particularly when heat sterilization is not suitable.
Why Use Filtration for Sterilization?
Unlike methods like autoclaving which use high heat, filtration removes microorganisms physically. This makes it an essential technique for sterilizing liquid media that contain heat-sensitive components (such as vitamins, proteins, or growth factors) that would be damaged or degraded by high temperatures.
How Filtration Works
Sterilizing filtration involves passing the liquid media through a membrane filter with pores small enough to capture and remove bacteria, fungi, and other particles. The effectiveness of filtration as a sterilization method relies on using filters with specific pore sizes designed to retain microorganisms.
Sterilizing Grade Filters
As current practice, sterilization of media is achieved by using nominal 0.2-micron–rated sterilizing grade membrane filters. These filters are designed to remove bacteria, which are typically larger than 0.2 micrometers.
For media containing animal sera or other components where smaller contaminants might be a concern, such as mycoplasma, an even finer filter may be used. For media containing animal sera, a final sterilizing grade 0.1- micron–rated filter may be used for added protection against mycoplasma. Mycoplasma are among the smallest free-living bacteria and require filters with smaller pore sizes for effective removal.
By selecting the appropriate filter pore size, filtration ensures the removal of microbial contaminants, resulting in sterile media ready for sensitive applications like cell culture or fermentation without compromising the integrity of heat-labile ingredients.
