I have membrane samples with biofilms on the surface and I would like to know how best to preserve it until I can observe it under the microscope? I will be using the SYTO 9 dye and Propidium Iodide before observing it under the fluorescence microscope or CLSM. I will need to preserve it for 7-10 days at most.
Dear Nurshaun,
You can use one of the general preservation methods for microorganisms:
PRESERVATION
Microorganisms require special preservation methods in order to ensure optimal long-term viability and genetic stability.
In general each preservation method can be assigned to one of the following groups:
1. Metabolically inactive preservation techniques (CABRI accepted methods)
1.1. Cryopreservation
1.1.1. Freezing and low temperature storage in or above liquid nitrogen
1.1.2. Freezing and low temperature storage below -70°C
1.2. Drying
1.2.1. Preservation by shelf freeze-drying
1.2.2. Preservation by spin freeze-drying
1.2.3. Preservation by liquid drying (L-drying)
1.2.4. Preservation by vacuum drying
2. Metabolically active methods
2.1. Periodic transfer on agar or in liquid medium
2.2. Keeping agar cultures under mineral oil
Maintenance of strains by metabolically active methods should be used only in case a strain cannot be preserved by one of the metabolically inactive methods, or in addition to one of these methods.
Flow charts for preservation methods are given in M/1998/3.00 Appendix 1 and M/1998/3.00 Appendix 2. Examples of preservation methods used in CABRI collections are summarised in M/1998/3.00 Appendix 5.
For the protection of cells against damage during freezing and (freeze)-drying as well as during storage microorganisms are normally suspended in a protective suspension medium. Some examples are described in M/1998/3.00 Appendix 3. M/1998/3.00 Appendix 4 gives an example of a protocol form for preparing protective media.
The preservation methods used in the collections may differ. Each collection must maintain detailed protocols of the applied preservation methods and their application to specific groups of microorganisms. Examples of them are given in M/1998/3.00 Appendix 5.01 to 5.13. If available, registration form for freeze-drying process per batch (e.g. vacuum, product temperature, shelf temperature, condenser temperature, time) should be filed.
Hoping this will be helpful,
Rafik
http://www.cabri.org/guidelines/micro-organisms/M300.html
You can try the advanced methods but it might also be worth to try to just keep them refrigerated or frozen at 20 °C. Try to split a sample and see how the methods compare.
Thank you very much Dr. Rafiq and Dr. Henrik, I will try out both your suggestions and see which method suits my needs best.
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