2.4.2. Preservation of in vitro cultures

Aspergillus has been observed to lose sporulation capacity and virulence after a couple of transfers on a standard medium (Scully and Bidochka, 2006). Therefore we recommend long-term storage of the isolates during the first transfers. Several long-term storage methods can be used:  frozen in skim milk, refrigerated with silica gel, or freeze dried. It is possible to successfully recover various Aspergillus species (e.g. Asp. flavus, Asp. parasiticus and Asp. niger), stored in 10 % glycerol at -80 °C for more than a year, using the same method which we recommend for A. apis (see paragraph 1.4.3.1. Cryopreservation in glycerol at -80°C).