Survival of yeasts stored after freeze-drying or liquid-drying

Abstract

IntroductionFreeze-drying and L-drying are popular methods of preserving microorganisms, because long-term viability is excellent in most cases and the storage and distribution requirements are simple. By plotting the survival curves of freeze-dried species sealed under high vacuum ( 1 Pa) and stored at 5 C in the dark, we previously found that the survival rates of Gram-positive bacteria immediately after freeze-drying and during storage were higher than those of Gram-negative bacteria (Miyamoto-Shinohara et al., 2008). In addition, the survival rate of the yeast Saccharomyces cerevisiae immediately after freeze-drying was lower than those of bacterial species, although S. cerevisiae survival rates were stable during storage (Miyamoto-Shinohara et al., 2000.To increase the survival rates of S. cerevisiae strains, we tested the applicability of L-drying, in which cells are desiccated by vacuum evaporation at room temperature. In contrast, during freeze-drying, cells are desiccated by sublimation. L-drying is effective for the long-term preservation of cultures sensitive to freezedrying (Malik, 1990(Malik, , 1999. In this research, yeast strains were L-dried according to the method of the Institute for Fermentation, Osaka (Banno et al., 1979), in which the cell suspension was dispensed into a glass ampoule (in the same way as for freeze-drying) and a cotton wool plug was inserted to prevent the temperature in the ampoule from falling to the freezing point (Iijima and Sakane, 1973).To clarify the mechanisms underlying tolerance to L-drying and freeze-drying, we investigated the survival of type strains of various yeast species. The survival J. Gen. Appl. Microbiol., 56, 107 119 (2010) We investigated

Influence of freezing temperatures prior to freeze-drying on viability of yeasts and lactic acid bacteria isolated from wine

“…As Miyamoto‐Shinohara et al . () also pointed out, we observed that yeast size could be another reason to explain the differences in survival in the yeast group: the larger the yeast was, the lower the recorded survival. So P. membranifaciens , S. bacillaris, M. pulcherrima and T. delbrueckii (with a size range of 1·8–6 × 3–17 μ m) were more resistant to freeze‐drying than larger yeasts H. uvarum , S. pombe or D. bruxellensis (size range of 1·5–7 × 2·5–28 μ m); the sizes of these yeasts species were obtained from Kurtzman and Fell ().…”

“…As pointed by other authors, cell wall and membrane composition strongly affects yeast survival after freeze‐drying (Miyamoto‐Shinohara et al . ). In general, yeast walls are composed of 85–90% polysaccharide and 10–15% protein.…”

“…Miyamoto‐Shinohara et al . () found a relationship between osmotolerance of yeasts and tolerance to freeze‐drying. We observed that the strains of species P. membranifaciens , M. pulcherrima, T. delbrueckii, H. uvarum, P. kudriavzevii and W. anomalus , all of which have been reported as being osmotolerant (Wang et al .…”

“…Miyamoto‐Shinohara et al . () stated that the larger the amount of glucan in yeast walls, the higher the survival rate is after freeze‐drying. However, glucan may also trap moisture, which can lower survival during storage.…”

Optimization of air-blast drying process for manufacturing Saccharomyces cerevisiae and non-Saccharomyces yeast as industrial wine starters

“…A study by Kim et al (2016) reported that S. cerevisiae D8, H. uvarum S6, and I. orientalis KMBL5774 entrapped in 2% Ca-alginate beads by air-blast drying showed 90.67, 90.81, and 87.04% survival rate when 10% skim milk and 10% sugars (sucrose, trehalose, and glucose for S. cerevisiae D8, H. uvarum S6 and I. orientalis KMBL5774, respectively) were used as protectants. Miyamoto-Shinohara et al (2010) reported that I. orientalis had an 8.6 and 28.2% survival rate on freeze-drying and liquid drying, respectively, without any protective agent.…”