Dear Aman Allah

These, all methods used in bacterial preservation, choose the suitable one for your work

Lyophilization, or storage at -70°C or below are the best methods for long term preservation of bacterial culture and generally storage of isolates at -20°C is not recommended.

📷Freeze Dryer

Lyophilization

Most organisms may be successfully stored after lyophilization (freeze-drying).

Freeze-drying involves the removal of water from frozen bacterial suspensions by sublimation under reduced pressure. Lyophilized cultures are best maintained at 4°C or lower. Sublimation occurs when a frozen liquid goes directly to a gaseous state without entering a liquid phase.

The freeze-drying process results in a stable, readily rehydrated product. This process consists of three steps:

It is recommend using slow rates of cooling as this will result in the formation of vertical ice crystal structures, thus allowing for more efficient water sublimation from the frozen product. Freeze-dried products are hygroscopic and must be protected from moisture during storage.

Preservation in Glycerol at –20 °C

Mineral oil at room temperature

Stab cultures at room temperature is used for non-fastidious organisms only, such as staphylococci and Enterobacteriaceae

Stab cultures in cystine trypticase agar (CTA) method is recommended for the preservation of  Neisseriaand streptococci

Cooked-meat medium is used for the preservation of anaerobes

Hello Aman! If you wish to preserve the samples for a shorter duration, you can go ahead with stab culture. But for a long term preservation, you can choose either lyophilisation or freezing at - 70°C. As per your query, addition of 15% glycerol to Brain Heart infusion broth should be appropriate for storage.

Hi, 15% Glycerol at -70-80°C will definitely work for MRSA

thank you all for your valuable suggestions

Hello Aman, I used, 20 % Glycerol and MRS at -80 °C , conservation of Lactobacillus.

Los aislamientos fueron conservados en el banco de cepas del laboratorio a -80oC en caldo MRS (Britania) suplementado con glicerol estéril al 20 % (Merck, Darmstadt, Germany) para los futuros análisis.