A contribution to the quantitative evaluation of yeast cultures stored in liquid nitrogen.

Different ways of the evaluation of viability of cultures stored in liquid nitrogen are compared. The streaking technique is recommended for a rapid evaluation. It is sufficient to determine the suitability of the medium, of cryopreservatives and of the whole procedure. On storage of melted cultures for 1-7 d at 4 degrees C it was found that the cultures could be transported directly in a suitable package maintaining the low temperature on the condition that the transportation would not last longer than 5 d.