A comparative study between different preservation methods on the viability of some yeast cultures

The influence of chilling, freezing, and drying preservation methods on morphological properties and viability of four yeast cultures, isolated Saccharomyces boulardii (SB1 and SB2), Saccharomyces cerevisiae (SC), and Kluyveromyces lactis (KL), was studied. chilling preservation had no effect on yeast colony morphology parameters till the end of the preservation period in contrast with freezing and drying preservation methods. Drying preservation resulted in the highest viability decrement % of yeast cultures ranged between 59.38 to 40.21% as compared with other preservation methods. There is a noticeable reduction in D values of preserved yeast cultures by drying, which varied from (33 to 26 day) in comparison to chilling and freezing preservation that recorded (119 to 83 and 180 to 57 day), respectively. The obtained results revealed that chilling preservation under proper conditions, as well as freezing, is more preferable for the preservation of studied yeast cultures than that preserved yeast by the drying method.