FAQ - Frequently Asked Questions

  1. What is the best way to thaw serum?
  2. What is the recommended storage temperature?
  3. How long the serum can be stored between +2 to +8°C?
  4. What are the precipitates in the serum?
  5. Are Biowest products sterile?
  6. Why heat inactivating the serum?
  7. How the serum should be heat inactivated?
  8. Is it normal that the trypsin products have not always the same colour?
  9. How are selected the samples for the sterility tests on sera?
  10. How are tested the viruses?
  11. What means USDA approved?
  12. What makes Biowest a serum specialist?
  13. Why traceability is important? How does Biowest guarantee traceability?
  14. What is unique about Biowest?
  15. Where is FBS used?
  16. What makes Fetal Bovine Serum (FBS) different?
  17. What is BSE?
  18. What about BSE risk in serum products?
  19. Bovine Spongiform Encephalopathy (BSE): important when choosing origin of FBS?
  20. Do I need to test FBS from Biowest?
  21. How do I select FBS for stem cells?
  22. How should I select my FBS supplier?
  23. How FBS is collected?
  24. What about animal welfare?
  25. Why kill pregnant animals?
  26. Do the animals suffer?
  27. What about the ethics?
  28. What about the global FBS supply?
  29. What about demand: Why is use of FBS increasing?
  30. Are some origins of FBS of better quality than others?
  31. When all origins equal, why different prices for different origins?
  32. Why is FBS less expensive in Europe than in USA?
  33. What about regulations and compliance?
  34. What is ISIA?

1 - What is the best way to thaw serum?

Remove the serum from frozen storage and let it overnight at room temperature. On the next morning slightly agitate the serum to homogenize it without making foam.
The agitation is the key to avoid the formation of crystalline or flocculent precipitates.
If "cryprecipitates" appears, they are not toxic to cell cultures, they only affect the appearance and consistency of the serum.

2 - What is the recommended storage temperature?

The serum should be stored frozen and protected from light. The recommended storage temperature is -10°C to -40°C.
At temperatures below -40°C, the bottles may become brittle resulting in an increased risk of breakage.

3 - How long the serum can be stored between +2 to +8°C?

Serum may be stored between +2 to +8°C up to 8 weeks without diminished performance(*).
More recent internal studies have shown that the capacity of the serum to promote the cell growth after storage of 26 weeks between +2 and +8°C have not been significantly altered.
(*) Art to Science, Vol.19, No.2, "Serum Stability at Refrigerated Temperatures (2-8°C).

4 - What are the precipitates in the serum?

Turbidity and flocculent material may be present after thawing or after prolonged freezer and/or refrigerated storage. Our experience indicates these modifications don't affect the biological performance of the serum.

  • Some precipitates are precipitates of fibrin:
    Our collection procedures and rapid freezing may leave some fibrinogen in the serum. Fibrinogen is the soluble precursor of the clot-forming protein fibrin. The fibrin may appear after thawing or heat inactivation. Fibrin does not alter the capacity of the serum to promote the cell growth. It is recommended to use the serum without treatment (filtration or centrifugation).
  • Some precipitates are precipitates of Calcium Phosphate:
    Serum that is incubated at 37°C for extended periods will become cloudy and precipitates appear. Those precipitates are composed of calcium and phosphorous. To the best of our knowledge, this does not alter performance of the serum as supplement of cell culture.

5 - Are Biowest products sterile?

Except where written on products labels, Biowest sera and liquid media are sterile filtered. Sterility is not guaranteed after opening. The use of aseptic techniques of manipulation is recommended.

6 - Why heat inactivating the serum?

For most cell culture applications, heat inactivation of serum is not recommended.
Heat inactivation degrades complement proteins that may interfere with immunological assays.
Heating serum for prolonged periods of time can reduce or destroy growth factors, as well as increase the formation of precipitates which are commonly mistaken for microbial contamination.

7 - How the serum should be heat inactivated?

  • Begin the thawing of the serum at room temperature during a night, as well as the control serum bottle.
  • Stir the serum in bottles because a gradient appears during the thawing, then place them in the water bath adjusted at first at 80°C.
  • When the temperature of the control bottle reaches 50°C, then put the thermostat of the bath to 70°C ; when the temperature in the bottle reaches 55°C, put the thermostat to 60°C.
  • When the serum reaches the temperature of 56°C, switch on the stopwatch (30 minutes is the registered time) and put the thermostat of the water bath to 56°C. During the 30 minutes, verify the temperature regularly and maintain it stable by adjusting the thermostat, by adding some cold water, by lowering the lid or not. Stir the serum every 5 to 10 minutes.
  • Keep the serum at room temperature during 30 minutes, and then freeze the serum at -20°C.

- The stirring is crucial for a good quality of serum. If the serum is not correctly mixed, a gradient of salts, proteins and lipids will be appeared and allowed the formation of crystalline precipitates and the flocculation. Those precipitates are not toxic for the cell culture but affect the appearance and the consistency of the serum.
- To heat serum during a long period can destroy the growth promoters. That can also increase the development of precipitates.

8 - Is it normal that the trypsin products have not always the same colour?

Some references of trypsin contain phenol red. The product is shipped with dry ice and there could be significant CO2 build up in the package. This CO2 may enter the solution and lower the pH slightly, giving an orange (around pH 6.5) vs. pinkish (around 7.3) color. The solution, if orange (acidic) should still be good to us as is, or sodium hydroxide may be added to adjust the pH.

9 - How are selected the samples for the sterility tests on sera?

The samples are collected during the bottling.
List of the samples taken:

  • one sample of minimum 10ml at the beginning, middle and end of the process for each bottling place.
  • a sample of minimum 10ml every 75 bottles, for each filtration place.

10 - How are tested the viruses?

Biowest tests the viruses (BVD, IBR, PI3) by a culture method, it means that only live viruses will be detected if there are ones in the serum.
Simple PCR, not combined with a culture method is a method which detects DNA and RNA of viruses that are alive and dead.
So if an animal, for example, was in contact with a BVD but is not anymore infected by the virus, its blood will keep traces of RNA of the virus. In this case, the PCR will be positive, but as there is no more live virus, the Biowest method won't detect the virus.
All the Biowest viruses' tests are made by an independent veterinary laboratory.

11 - What means USDA approved?

It means that the sourcing of the serum is an USDA approved country. The serum is produced from blood collected in countries that have been approved by the United States Department of Agriculture (USDA) for export of products into the United States. Eligible countries for export into the U.S. of fetal bovine serum include Australia, Canada, Chile, Costa Rica, Honduras, Iceland, Japan, Mexico, New Zealand, Nicaragua, Uruguay.

12 - What makes Biowest a serum specialist?

More than 25 years with serum as main activity, dedicated to quality and service ; vertical integration, covering the widest range of origins.

13 - Why traceability is important? How does Biowest guarantee traceability?

Traceability is important for  using what is allowed and for getting what you  pay for. 

Biowest has complete control of the supply chain from harvesting the raw material to filling sterile bottles; Bureau Veritas April 2012 certifies compliance with the ISIA guidelines. Our traceability with SAP software: SAP Business One software allows us to guarantee a complete traceability of the products, from raw material up to the delivered end product. This solution plays a key role in the complete supply network traceability - adding global batch traceability capabilities for determining batch genealogy.

14 - What is unique about Biowest?

Taking full responsibility to ensure a vertically integrated supply chain for the highest level of quality, traceability and security. 

15 - Where is FBS used?

FBS (Fetal Bovine Serum) is most widely used in various in vitro research fields such as vaccine development, cell therapy and stem cell.

16 - What makes Fetal Bovine Serum (FBS) different?

FBS is principally a natural product. All FBS batches are UNIQUE, with specific characteristics, different from all other batches. 

17 - What is BSE?

Bovine spongiform encephalopathy (BSE), commonly known as mad cow disease, is a fatal neurodegenerative disease (encephalopathy) in cattle.

18 - What about BSE risk in serum products?

OIE analyzes the BSE risk of all member countries. The best BSE ranking is "Negligible BSE risk". OIE members recognized as having a negligible BSE risk include Argentina, Australia, Brazil, Chile, Colombia, Scandinavian countries, New Zealand, Panama and Uruguay. The second best  BSE ranking is "Controlled BSE risk". For more details, refer to link http://www.oie.int/?id=495

19 - Bovine Spongiform Encephalopathy (BSE): important when choosing origin of FBS?

The blood products, as plasma and serum, have been found to be safe, along with milk and a few other products.


The OIE chapter covering BSE reads as follows:  


1) When authorising import or transit of the following commodities and any products made from these commodities and containing no other tissues from cattle, Veterinary Authorities should not require any BSE related conditionsregardless of the BSE risk status of the cattle population of the exporting country, zone or compartment:

a) milk and milk products; 


h) blood and blood by-products, from cattle which were not subjected to a stunning process, prior to slaughter, with a device injecting compressed air or gas into the cranial cavity, or to a pithing process.


(2013 © OIE - Terrestrial Animal Health Code 1 CHAPTER 11.5 ; Article 11.5.1) 

20 - Do I need to test FBS from Biowest?

FBS from Biowest has been tested on multiple cell lines. Batches selected for sales without testing are sold with performance guarantee. You can save time by purchasing pretested FBS from Biowest.

21 - How do I select FBS for stem cells?

In addition to the normal testing, Biowest also tests the cells for suitability for stem cell work. Nevertheless, it is recommended that batches used for stem cells are tested on the specific cell lines and conditions that you require. Dr Yamanaka in his Nobel Prize winning work related to stem cells selected Biowest FBS after trying out our batches.

22 - How should I select my FBS supplier?

The choice of FBS supplier should be based on Quality, Traceability and Security of full supply chain, supported by comprehensive documentation.

23 - How FBS is collected?

FBS is collected from cows, slaughtered in compliance with OIE guidelines and standards for veterinary inspection.

24 - What about animal welfare?

OIE's guidelines for animal welfare are respected in the countries where the FBS is collected.

25 - Why kill pregnant animals?

Slaughtering of pregnant animals is in most cases an unplanned event. The frequency depends on farming technique. In most cases, the condition of gestation is unknown ; especially where animals are produced naturally ; in the case of cattle moving freely around, grass fed, heifers and steers together. No cows are killed with the main purpose of harvesting the fetal blood. The blood is collected as a byproduct from cattle slaughter operations focused on the bovine meat. The pregnancy rate is low, the condition of pregnancy unknown when an animal enters the slaughtering line.

26 - Do the animals suffer?

The collection of the blood is done without causing pain for the fetus. The fetus's life ends through oxygen depletion, generally agreed to be a gentle method of life termination. Through cell culture, it is possible to reduce the use of live animals in science. And research is being done to produce meat by cell culture, which conceivably could ultimately lead to the end of breeding animals for food.

27 - What about the ethics?

Given that killing of some pregnant animals is unavoidable, it is better to make use of the fetus, serving science and generating jobs. The benefit obtained from the unborn calves through their contribution to science cannot be overstated.

28 - What about the global FBS supply?

Availability of FBS is shrinking, as demand increases. Opening up collection in new geographies has historically compensated for the shrinkage.  Present world supply of FBS is short and decreasing.

29 - What about demand: Why is use of FBS increasing?

FBS demand is growing along with latest research developments such as stem cells, cell therapy, and proteomics.

30 - Are some origins of FBS of better quality than others?

Origin has no proven influence on growth of cells. Batches may work well for one specific cell line, but not for another one. "Serum quality" is specific for each cell line. That is why testing of FBS is widely used when dealing with sensitive cell lines. Biowest performs the most extensive analysis of biochemical parameters and testing on cell lines in the industry, making the results available on the COAs.

31 - When all origins equal, why different prices for different origins?

Due to regulations limiting trade and because of marketing, New Zealand is perceived to have "superior" veterinary status. In reality, many other countries are in same veterinary risk category, according to OIE's classification. EU and USA are working to harmonize trade rules. If successful, this will contribute to harmonizing price levels for most origins of FBS.

32 - Why is FBS less expensive in Europe than in USA?

Imports of FBS into EU is less restricted than in USA.  A proposal made by USDA 1994 to apply same FBS import policies as EU did not get support from the US FBS industry. The International Serum Industry Association (ISIA) supports efforts to harmonize import rules, suggesting to follow the recommendations of the OIE. In the meantime, FBS in USA remains twice as expensive as in Europe.

33 - What about regulations and compliance?

FBS can be adulterated ie. with addition of water or unknown FBS origins. For example in 2013, a large product recall was made in EU and USA , affecting serum product from PAA, underlining the importance of selecting serum suppliers with maximum care.

34 - What is ISIA?

ISIA, International Serum Industry Association, has, as its main tasks, to establish traceability guidelines and harmonize international import rules.  Working with companies adhering to the ISIA guidelines eliminates the risks of purchasing adulterated products. ISIA is working with authorities worldwide.



RPMI 1640 w/ L-Glutamine (ACF)

Biowest proposes now product RPMI 1640 w/ L-Glutamine (Animal Component Free).  

FBS flyer has been published

Biowest promotes new quality Fetal Bovine Serum

RPMI 1640 w/ L-Glutamine (ACF)

Biowest proposes now product RPMI 1640 w/ L-Glutamine (Animal Component Free).