Culture Maintenance: Transfer Rooms/Dead Air Spaces

The most versatile sterile rooms for transferring or working with axenic cultures have proved to be small rooms like a hallway closet with little to no air circulation. A fixture containing a germicidal UV lamp is mounted on the wall or ceiling above the level of the eyes and arranged so that its rays cannot be seen at any time the person is either standing or seated in the transfer room. The light is turned on after work is completed in the room--typically at the end of the day, and then turned off prior to entering the room. To ensure sterility the irradiance must exceed 1000 mJ/cm2 (Klein and Kleing 1970). The greatest asset towards preventing contamination in handling cultures lies in having such a room in which the surfaces may be kept wiped clean with 70% ethanol and thus prevent the dirt, dust and contamination found in unprotected areas.