Both methods are employed for such strains. Upon receipt of a new culture, a transfer is made to a fresh slant. An adequate amount of conidiating material is generally produced within 4 days, the strain is then processed. In the case of sparsely conidiating cultures, the amount of fresh material can be increased by growing more than one slant. The aim is to maximize the number of viable conidia in the suspension fluid used for preservation.
Some colonial strains require a longer period before finally producing abundant conidia.
Recognition of this character comes through trial and error - with such strains the culture tube can be sealed with a permeable membrane cap to retard drying. When an adequate amount of material has grown, preservation on silica gel and in lyophil can be accomplished at the same time. 2.0 ml is an adequate volume. The mycelial-conidial mass is loaded into the milk with a sterile loop or needle. Normal concentrations of conidia can usually be suspended by agitation with the tip of a Pasteur pipette, but cultures that are largely aconidial will require grinding with a stouter implement.