Thermal Tolerance and Sterilization Conditions of Common Microbial Contaminants in Cell Culture
Common microorganisms that contaminate cell cultures include Escherichia coli, Staphylococcus aureus, yeast, mold, mycoplasma and viruses. Under what conditions can these microorganisms be inactivated?
1) Escherichia coli
E. coli has low heat resistance. Soaking in hot water at 60°C for 30 minutes achieves sterilization; heating at 70°C for approximately 3 minutes kills the bacteria; boiling water at 100°C inactivates them within 1 to 3 minutes.
2) Staphylococcus aureus
Vegetative cells of spore-free S. aureus have moderate heat tolerance and cannot withstand high temperatures. A 60°C water bath for 30 minutes eliminates the vast majority of viable bacteria; treatment at 70°C for 10 minutes completely inactivates vegetative cells.
3) Yeast
Yeast cells generally cease growth above 47°C. Their optimal growth temperature ranges from 20°C to 30°C, and the optimal fermentation temperature is 40–42°C. Yeast cells are killed within minutes at 55–56°C.
4) Mold
Molds readily survive and reproduce in dark, humid environments at 20–30°C. Heating most molds to 80°C and holding for 20 minutes achieves disinfection. However, mold spores (reproductive propagules) are highly heat-resistant and difficult to eliminate with boiling water at 100°C; high-temperature treatment at 121°C for around 10 minutes can largely inactivate spores.
5) Mycoplasma
Mycoplasma are simple bacteria lacking cell walls and are recognized as the smallest self-replicating organisms (typically 0.1–0.3 μm in diameter). Their optimal growth temperature is 35°C, and they are highly heat-sensitive. Exposure to 100°C for 5 minutes completely kills mycoplasma.
6) Viruses
Viruses are generally susceptible to heat. Most viruses become inactivated after 30 minutes at 55–60°C, and only a few seconds of boiling at 100°C is sufficient for full inactivation.
Post time: Jul-09-2026