Sterilization of bioreactors prior to inoculation Which method is standard for sterilizing a stainless-steel fermentor vessel and associated lines before a production run?
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ADry heat in a hot-air oven
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BSteam under pressure (steam-in-place / SIP)
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CSimple boiling with water at atmospheric pressure
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DAll of these equally
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EUltraviolet lamps inside the vessel
Answer
Correct Answer: Steam under pressure (steam-in-place / SIP)
Explanation
Introduction / Context:Sterility is essential to prevent contamination and ensure predictable fermentation performance. Large vessels and complex piping demand validated in situ sterilization methods.
Given Data / Assumptions:
- Industrial fermentors are typically steam-rated stainless-steel systems.
- Goal is terminal sterilization of vessel, lines, and filters.
Concept / Approach:Steam under pressure (121–134 °C) provides moist heat that denatures microbial proteins and nucleic acids effectively, penetrates crevices, and is practical for clean-in-place/steam-in-place operations. Dry heat ovens are impractical for large tanks; boiling at 100 °C may not achieve sterility for resistant spores or inaccessible areas.
Step-by-Step Solution:
Identify required lethality: moist heat at elevated temperature is industry standard.Match to method: SIP cycles deliver validated F0 values throughout the system.Exclude alternatives unsuitable for large, closed vessels.Verification / Alternative check:GMP facilities document SIP parameters and biological indicator results to verify sterilization.
Why Other Options Are Wrong:
- Dry heat ovens: not feasible for intact, plumbed reactors.
- Boiling: insufficient sterilization assurance level.
- UV: limited line-of-sight, poor penetration; used for rooms, not complex piping.
- “All equally”: incorrect; SIP is the validated standard.
Common Pitfalls:Ignoring valve bodies and dead legs during SIP; inadequate condensate removal reduces heat transfer.
Final Answer:Steam under pressure (steam-in-place / SIP)