Q.42 Match the entries in Group I with the methods of sterilization in Group II.
Group I Group II
P. Serum 1. Autoclave
Q. Luria broth 2. Membrane filtration
R. Polypropylene tubes 3. UV irradiation
S. Biological safety cabinets 4. Gamma irradiation
5. Dry heat
(A) P-5, Q-3, R-1, S-4 (B) P-1, Q-4, R-5, S-3
(C) P-2, Q-1, R-4, S-3 (D) P-4, Q-1, R-3, S-5
Sterilization ensures aseptic conditions in microbiology and biotechnology labs, preventing contamination during microbial fermentation, cell culture, and recombinant protein production. Heat-labile biologicals require filtration, while resilient media withstand autoclaving. Plastics demand radiation or specialized methods matching material compatibility with microbial kill efficacy.
Item-Sterilization Technique Matches
Serum (P): Heat-labile animal serum (FBS) sterilized by 0.22 μm membrane filtration to preserve growth factors and cytokines essential for mammalian cell culture.
Luria broth (Q): Nutrient-rich LB media autoclaved at 121°C, 15 psi for 15-20 min, standard for E. coli recombinant protein expression.
Polypropylene tubes (R): Disposable plastic labware sterilized by gamma irradiation (25 kGy Co-60 source) during manufacturing, penetrating packaging completely.
Biological safety cabinets (S): Class II/III BSCs sterilized by UV irradiation (254 nm) between uses, targeting surfaces without damaging HEPA filters.
Group II Methods
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Autoclave: Moist heat sterilization (121°C steam)
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Membrane filtration: 0.22 μm sterile filtration
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UV irradiation: Surface DNA damage
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Gamma irradiation: Penetrating ionizing radiation
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Dry heat: High-temperature incineration
Correct Answer
Option (C) P-2, Q-1, R-4, S-3 represents standard laboratory practice.
| Group I | Item | Matches | Method | Application Context |
|---|---|---|---|---|
| P | Serum | 2 | Membrane filtration | FBS for CHO/HEK cells |
| Q | Luria broth | 1 | Autoclave | Bacterial media prep |
| R | Polypropylene tubes | 4 | Gamma irradiation | Pre-sterilized disposables |
| S | Biological safety cabinets | 3 | UV irradiation | Workspace decontamination |
Option Explanations
(A) P-5, Q-3, R-1, S-4: Incorrect. Serum destroyed by dry heat (160°C); Luria broth UV ineffective through glass; polypropylene autoclave incompatible (melts).
(B) P-1, Q-4, R-5, S-3: Incorrect. Serum proteins denature in autoclave; Luria broth gamma overkill (expensive); polypropylene dry heat warps plastic.
(C) P-2, Q-1, R-4, S-3: Correct. Filtration preserves serum bioactivity; autoclave standardizes LB; gamma penetrates tube packaging; UV surfaces BSCs effectively.
(D) P-4, Q-1, R-3, S-5: Incorrect. Serum gamma irradiation damages proteins; polypropylene UV ineffective (opaque); BSCs dry heat impractical.
Biotechnology Process Context
Serum filtration maintains 95%+ bioactivity for mammalian cell yields >10^7 cells/mL. LB autoclaving ensures sterile 50L fermenter fills. Gamma-sterilized tubes enable GMP-compliant workflows. BSC UV reduces CFU/m² by 4-log between electroporations. For your fermentation work, matching sterilization to material prevents >90% contamination losses, optimizing enzyme/antibody production economics.
