JM Bioscience, a Fetal Bovine Serum (FBS) supplier serving the research needs of the life science community

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Frequently asked questions

What is Fetal Bovine Serum (FBS)?

FBS is a growth-promoting supplement used in tissue culture for virtually all types of cells and is also known as foetal bovine serum, and fetal/foetal calf serum (FCS) . FBS is a complex mixture of nutritional, growth, hormonal, and attachment (anti-trypsin activity) factors that are essential for cell propagation. These include a wide variety of proteins, lipids, salts, minerals, and amino acids. Major proteins include albumin, fetuin, fibronection, globulins, and transferrin. Furthermore, FBS also appears to serve as a protective buffer against detrimental changes, such as pH differences, heavy metals, proteolytic activity, and endotoxin. Other types of sera include calf serum (CS), goat, and horse serum.

How is it processed?

Raw sera is collected by aseptic cardiac puncture at the abattoir by a licensed veterinarian. It is quickly refrigerated, and after allowing sufficient time (usually 24 hours) for clotting , the raw sera is centrifuged to remove blood cells. It is then prefiltered (submicron filtered), and finally sterile-filtered through a series of at least three 0.1 um filters. Processing is carefully performed at 4C to minimize product degradation, and the FBS is immediately frozen after processing.

Can FBS be used past its expiration date?

Possibly. While we guarantee FBS from five years from the date of processing, it is most likely viable for several years past that, assuming that it has been stored properly (at -20C or below), and not subject to multiple thawing/refreezing cycles. We recommend that you performance-test the FBS before usage to confirm viability. If you do not have a protocol for doing so, please contact us for one. In addition, while is not necessary for unopened and properly stored FBS, you may also consider sterile re-filtration (0.1 um) before performance-testing, especially if storage and handling conditions are uncertain.

How can FBS be heat-inactivated?

Heat inactivation is generally used to inactivate component proteins in the FBS which may interfere with immunological assays. Heat inactivation also inactivates certain viruses and may reduce the mycoplasma titer. Insect cells usually require heat-inactivated FBS. Thawed FBS may be heat-inactivated by incubating it for 30 minutes in a 56C water bath. The FBS should not be agitated during this time. Cool before using on cells.

Should FBS be virus-filtered?

In general, normal processing using sterile filtration (0.1 um) will not effectively remove viruses. Several companies have developed smaller pore filters (40 nm) which they claim will remove viruses or reduce viral loads. This is an option if you have virus concerns. Note that some larger proteins (e.g., IgM) may also be removed by these smaller pore filters.

Why is there lot-to-lot variability?

As FBS is a complex mixture of biological products, there is extensive lot-to-lot variation, even within the same donor herd.

Why are these specific cell lines tested?

We test on five cell lines-many more than our competitors. BHK-21 and COS-7 are workhorse cell lines that are widely used in tissue culture. The HeLa cell line is another widely used cell line that is also an excellent for identifying high quality serum which supports better cell attachment and growth. The L-292 cell line is very sensitive to toxins. Sf9 is an insect cell line that requires high-quality FBS to generate a high baculovirus titer. In summary, our performance testing is extremely comprehensive-only the highest quality FBS will pass.

Why is your FBS is not working with my cells?

First, ensure that FBS is recommended for your cell line. For example, calf serum (CS), and not FBS, is advised for NIH/3T3 cells. We recommend consulting websites such as ATCC ( and DSMZ ( for media requirements and culturing conditions for specific cell lines. Tissue culture difficulties may be due to a wide variety of problems, such as poor aseptic technique, and sub-optimal culturing conditions. Otherwise, due to batch-to-batch variation, certain cell lines may require specific growth and/or attachment factors that may not be present in any particular lot of FBS.
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