Microbial occurrence in liquid nitrogen storage tanks: a challenge for cryobanking?

Area of Science:

• * Cryobiology and Biobanking
• * Microbiology and Contamination Control
• * Quality Management in Biological Storage

Background:

• * Biobanks store valuable biological materials using cryostorage, typically below -150°C in liquid nitrogen (LN).
• * A potential risk during cryostorage is microbial cross-contamination within LN storage tanks.
• * Ensuring the safety and quality of stored biological materials necessitates understanding and mitigating contamination risks.

Purpose of the Study:

• * To review and assess the occurrence of microorganisms in LN biobanks.
• * To identify potential sources and routes of microbial contamination in LN storage.
• * To provide recommendations for minimizing contamination risks and enhancing biobank quality management.

Main Methods:

• * Literature review summarizing data on microbial occurrence in LN storage tanks.
• * Assessment of contamination potential using culture-based and molecular detection methods.
• * Survey of awareness regarding microbial contamination among culture collections.

Main Results:

• * LN is generally not a primary source of contamination; microbial cross-contamination risk is low.
• * Culture-based and molecular techniques detected low microbial cell amounts, indicating rare cross-contamination.
• * Identified contamination sources include samples, LN, human microbiome, and the environment.

Conclusions:

• * The overall risk of microbial cross-contamination in biobanks is low with adherence to SOPs.
• * Recommendations include reducing ice crystal formation and using sealed sample packaging.
• * A risk assessment spreadsheet is provided to support biobank quality management.