A laboratory needs to sterilize serum-containing culture media. Autoclaving will denature the serum proteins. The best method of sterilization is:
- A Dry heat oven at 160°C for 60 minutes
- B Filtration through 0.22 μm membrane filter ✓
- C Pasteurization at 72°C for 15 seconds
- D UV irradiation
Explanation
Membrane filtration using 0.22 μm (or 0.45 μm) pore-size filters is the method of choice for sterilizing heat-labile liquids including serum, antibiotics, enzyme solutions, and hormone-containing media. The filter mechanically removes bacteria, fungi, and spores but does not remove viruses or prions, so filtration is termed 'sterilization' only in the context of bacterial removal. Autoclaving (121°C, 15 min, 15 psi) is the gold standard for heat-stable materials. UV irradiation kills surface organisms but does not sterilize liquids. Dry heat is used for glassware and oils.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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