Cold room (4°C)
A large (88 sq. ft.) walk-in cold room (Norlake, Inc.) is located in the lab for ready access to stored cultures. Temperature is rigidly controlled, with a deviation over 24 hrs of less than 0.2°C.
Cultures are stored in zip-loc bags on metal shelving; they are arranged alphabetically by INVAM code number. See how cultures are prepared for storage and cataloged. Center
shelves are on wheels so they can be moved for easy retrieval and
reshelving of cultures selected for manipulation or for distribution. No
field soils are stored in this room.
Dewar Flasks (-270°C)
Inocula obtained from the University of Florida were cryopreserved. Sieved material from pot cultures was transferred to 2 mL vials, which were then stored in metal racks positioned within two Dewar flasks filled with liquid nitrogen. These flasks were topped off bi-weekly to keep full. Regulations for transport across campus have become so stringent that this storage method no longer is feasible. About 60% of the accessions restarted in pot culture failed to grow, which is similar to results we obtained when testing cryopreservation with new materials. Of those that grew in culture, many were contaminated with P. occultum or A. morrowiae (both of which probably would survive a nuclear holocaust). All remaining stocks in these dewars now are being stored in a -80°C freezer.
We use a Virtis 2-K benchtop lyophilizer to determine if freeze drying is a viable alternative to cryopreservation. The main advantages of this approach are: (i) larger volumes of inoculum can be stored and (ii) material can be stored in any constant temperature room (e.g. cold room, lab, etc.). Experiments conducted to date indicate viability after processing varies with genus and even species within a genus. We are testing a new approach using Tyvek bags to freeze dry undisturbed contents of cultures grown for 90 days in 150 cm°3 cone-tainers. Once lyophilized, the Tyvek bags are transferred to a larger bag, a vacuum applied and then sealed and stored at 4°C.