How should fish intestinal contents be preserved during transportation for subsequent bacterial screening operations?

In experiments collecting fish intestinal contents for subsequent microbial screening (isolation and cultivation of microorganisms), transportation and preservation conditions are crucial for microbial activity and community structure. Here are professional recommendations applicable to most microbiological scenarios requiring isolation of anaerobic/facultative and aerobic bacteria:

 

Key principles for preservation during transportation:

1. Maintain low temperature (4°C) during transportation to inhibit metabolism.

• Immediately after sampling, place the samples in pre-cooled sterile centrifuge tubes or sample bags and transport them in an icebox/with ice packs.

• Do not freeze (-20°C or lower), as bacterial activity may be compromised, especially in scenarios requiring viable bacteria screening.

 

2. Avoid prolonged exposure to air (if screening for anaerobic bacteria).

• If the target includes anaerobic bacteria, it is recommended to use anaerobic sampling tubes (Anaerobe Transport Tube) or sealed containers filled with nitrogen.

• CO₂ anaerobic bags/anaerobic jars can be used for encapsulation.

 

3. It is advisable to add protectants (optional).

• If cultivation cannot be initiated immediately, mix the contents with sterile glycerol protective solution (10–20% glycerol) for temporary cold storage (4°C, <12 hours).

• Alternatively, aliquot and store samples at -80°C for preservation of microbial DNA/RNA, though this method is not recommended for viable bacteria screening.

 

4. Try to limit transportation time to within 24 hours.

• The faster the transportation, the better. It is recommended to transfer to the laboratory or cultivation base immediately after sampling.

• If the distance is far, dry ice transportation can be used (for DNA extraction/metabolomics/amplicon research), but it is not suitable for viable bacteria cultivation.

 

5. Other considerations:

• The use of alcohol, RNA later, and other preservatives is strictly prohibited: these will inhibit/kill bacteria, suitable for metagenomics or metabolomics, not for isolation and cultivation.

• Avoid repeated freezing and thawing: if temporary storage is needed, it must be frozen once and then quickly aliquoted for use.

• Prepare sterile consumables and cold chain tools in advance: be sure to prepare sterile freezing tubes, refrigerated boxes, sterile gloves, etc., before sampling.

 

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