Sterilization of bioreactors prior to inoculation Which method is standard for sterilizing a stainless-steel fermentor vessel and associated lines before a production run?

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:

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)