Fetal bovine serum (FBS) has been a critical mainstay in cell-based pharmaceutical research and bioproduction, providing the food for cells in ground-breaking research and drug development for more than 40 years. Its attractiveness lies in its broad applicability to an array of cell lines, availability and traditionally low cost.

But one of the most prevalent criticisms against using it as a media supplement is the lack of information surrounding its sourcing, processing and characterization. Thus, some companies have introduced so-called “defined” FBS products that attempt to maximize cell culture growth and bridge the gap between chemically defined serum free media and serum containing media through high levels of quality-control testing.

Since FBS is still a highly heterogeneous biologic that can introduce many unknown variables into a cell culture system, “defined” FBS is more of a marketing term than a scientific one. The only way to make an FBS product more defined would be to add more characterization tests, and the market currently is lacking these types of products, making this bridge between defined and undefined media tenuous at best.

In fact, FBS sold in the US has minimal formal testing requirements, such as adventitious agent and mycoplasma screening required by 9CFR regulations. Industry standards also encourage most FBS providers to test for hemoglobin and endotoxin, with both generally looked for by scientists. However, even here some FBS providers don’t provide quality control specifications and only report findings. The total number of FBS tests, which categories are tested for and how they are reported, vary from provider to provider.

To allow scientists to make more informed decisions about their experiments and FBS choices, Nucleus Biologics has recently increased the number of characterization tests seen on our Certificate of Analysis (CoA) from 59 to 78. This far surpasses industry standards, with most competitors testing for 40 to 60 factors only on their most expensive products, as can be seen in the table below. The difference in Nucleus Biologics’ level of testing is even more distinct when it comes to Australian sourced serum products, which are often tested for fewer variables as they are assumed to be “cleaner” because the country is known worldwide to have a low-viral risk. Examples of the number of tests completed on other Australia-sourced products, including some brands having as few as nine or less tests, can be seen here.

From a researcher’s perspective, there are many advantages to having higher levels of quality control testing and characterization in their serum. The more testing completed on a lot of FBS, the easier it is to anticipate how it will affect cell lines and assays. In some cases, extensive characterization and consistency can allow scientists to forgo lengthy lot testing prior to purchasing, which otherwise can incur extra laboratory technician time and consumables, cutting into tight experiment budgets.

Additionally, cytokines and growth factors are more important to some applications than others. For instance, for companies growing antibodies, it can be beneficial to know the amount of Immunoglobulin G (IgG) in their serum. While this is something that Nucleus Biologics tests for, it is not a piece of data that all brands provide. Finally, poor characterization and sourcing from multiple locations can introduce outside variables that may increase the likelihood of failed experiments, potentially adding up to tens of thousands of dollars in expenses.


Examples of tests that Nucleus Biologics performs beyond competitors include:

  • Tetracycline, and derivatives thereof such as chlortetracycline and oxytetracyline – with many scientists seeking antibiotic-free FBS for their experiments, Nucleus Biologics performs this test as validation to confirm its animals were raised without antibiotics.
  • Antibody Profile – this test goes beyond the 9CFR viral testing by identifying signs of previous viral infection in the host animal. Nucleus Biologics’ complete antibody profile (BVD, IBR, PT, EBL, etc.) validates the historically low likelihood that the animals have been exposed to these viruses.
  • Functional Assays – confirm cell viability and that Nucleus Biologics’ FBS will be effective in cell cultures before it is ever received by scientists. The tests are performed in common cell lines used in bioproduction.
  • Additional tests – like creatinine, bilirubin, triglyceride, transferrin and numerous others to further characterize the FBS.


Below is an excerpt of the testing completed by Nucleus Biologics in comparison to other FBS brands:

Nucleus Biologics Beyond (Australia Source) Hyclone Defined (US Source) Hyclone Characterized (US Source) Hyclone Characterized (Australia/NZ Source) GIBCO Certified (US Source) GIBCO Qualified (Australia/NZ Source)
Mycoplasma X X X X X X
Hormone profile X X X X
Viral screen (9CFR 113-53C) X X X X X X
Biological profile





Antibody profile X
Tetracycline screen X
Biochemical profile
Iron X X X X
Glucose X X X X X X
Cholesterol X X X X X
Triglyceride X X X X
Transferrin X X X


Nucleus Biologics mitigates potential risks from FBS, not only through increased testing, but also by its controlled process and exclusive-origin FBS product. The company’s supply chain has been designed to minimize viral risk and biologic variation through a dedicated, exclusive-source supply agreement with Australian Agricultural Company (AACo) as a raw material source. AACo is the largest cattle company in Australia (with 16m+ acres of land under its control), a country known to be BSE- and FMD-free. Additionally, our products are processed in ISO 9001:2008 Certified and FDA Registered Facilities following cGMP (Good Manufacturing Practices). Further, our unique supply relationships allow us to reinvent how FBS is purchased and offer multi-year fixed price agreements.

Discover how Nucleus Biologics has completely “re-defined” FBS to go beyond industry standards. Get a free sample here.