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Collection History
Strain Distribution Policies
Search the Catalog and Request Strains
Open Collection Deposit Form (PDF, 58kb)
   
Strain Deposits and Accessions

Microorganisms may be accepted into the open or public portion of the ARS Culture Collection. Strains to be deposited in the ARS Culture Open Collection must be accompanied by a completed and signed deposit form, available here [PDF, 58kb]. Please note that this now a saveable PDF that can be completed using a PDF reader. Please contact the Collection Manager, Mr. James Swezey (e-mail: james.swezey@ars.usda.gov) prior to sending your strains to determine if they can be accepted into the collection. Strains will not be accepted into the collection without prior approval.

 

 

 

Strain Maintenance

The majority of strains maintained in the ARS Culture Collection are kept as lyophilized (freeze-dried) preparations. Culture ampules in refrigerated storage are seen in the photo below on the left.

The first large-scale use of lyophilization for culture preservation was pioneered at NCAUR by Wickerham for yeasts and by Raper for aspergilli and penicillia. The process consists of freezing microorganisms within small glass ampules in an appropriate liquid suspending medium such as bovine serum and applying a vacuum to sublime the water from the frozen preparations. Following drying, the ampules are sealed under vacuum with a gas-oxygen torch and then stored at 5ºC. This process can be seen below on the right.

lyophilized preparation inventory sealing lyophiles
Some microorganisms, such as asporogenous filamentous fungi and certain yeasts and bacteria, do not survive the lyophilization process. These strains are maintained as frozen stocks in liquid nitrogen. Liquid nitrogen storage seems to
cause little or no genetic change in cells. The reasons for not relying on this method exclusively for preservation of cultures are: cost and the fact that lyophilized preparations may be shipped by regular mail whereas strains preserved by liquid nitrogen must first be grown on agar
or in liquid medium to avoid the expense of shipping frozen materials.
strain storage in liquid nitrogen


     
 
Updated 28-Nov-2011
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