Some factors affecting preservability of freeze-dried bacteria

Abstract

1. The use of sodium glutamate as a medium for freeze-drying Lact. bifidus significantly enhanced the stability of the dried product, especially the heat stability.2. The optimal concentration of sodium glutamate, as a drying medium, was found to depend on the bacilliary concentration; the higher the concentration of the bacilliary suspension used the higher was found to be the optimal concentration of the sodium glutamate.3. It was possible to classify various drying media according to the degree of sublimation of the product during the process of freeze-drying. Two types were observed; in the first, which included sodium glutamate and glucose, the sublimation rate diminished with the increasing concentration of the medium, whereas in the second group, which included polyvinyl pyrrolidon K 90 (PVP), soluble starch and dextran, no such diminution was observed when the concentration of the medium was increased.4. By the combination of sodium glutamate or glucose with a medium belonging to the second group sublimation was found to be promoted.5. The stabifity-conferring effect of sodium glutamate on dried Lact. bifidus was markedly enhanced when the glutamate was combined with a drying medium belonging to the second group. This effect is attributed to a desiccation-promoting property of the latter medium.6. Lact. bifidus as a freeze-dried preparation showed a somewhat better survival rate when sealed in air than when sealed in vacuo. In the case of other anaerobic organisms tested there was no significant difference in the survival rates under the two methods of storage.

Effect of suspending media on freeze-drying and preservation of vaccinia virus

“…The existence of an optimal concentration of sodium glutamate was essentially similar to that seen in BCG and Lactobacillus bifidus (Cho & Obayashi, 1956;Obayashi & Cho, 1957;Ota, 1959;Obayashi et al 1961). Obayashi et al (1961) suggested that the concentration of sodium glutamate is related to the residual moisture content of the final product, and that for the preservation of the product there existed an optimum residual moisture content. They observed that the increase in the concentration of sodium glutamate tended to depress the sublimation during the drying in contrast to soluble starch and PVP, in which no such diminution of sublimation occurred with increase of the concentration.…”

“…In the second group, sodium glutamate was used in combination with soluble starch, polyvinylpyrrolidone (PVP) or sodium carboxymethyl cellulose (SCMC). According to Obayashi, Ota & Arai (1961) the first group of substances exert a sublimation-retarding effect, whereas the second group of substances, such as PVP and SCMC, rather have a sublimation-promoting property.…”

Recent Advances in Freeze-Drying

“…Recently Obayashi, Ota and Shiro (1961) have suggested the use of polyvinylpyrrolidone as the protective colloid instead of dextran. From a limited experience, I have had good results using the K 30 fraction of polyvinylpyrrolidone with a mean molecular weight of 45,000 and also with Bayer's New Periston with a mean molecular weight of 11,500.…”

Recoveries of Bacteria After Drying on Cellulose Fibres

“…It would be of interest to test these and other carbohydrates in the absence of peptone for protective properties at relatively high temperatures. Similarly, in view of tlie work of Miller and Goodner (1953), Greaves (1959), and Obayashi et al (1961, a trial of sodium glutamate as a preserving agent with tlie present drying technique should be profitable.…”

“…Proom and Hcmmons (1949) tested exposure at 80° C. to indicate the likehhood of long-term survival of desiccates at ambient temperatures. More recently Greaves (1959) and Obayashi, Ota and Arai (1961) have exposed desiccates at 100° C. for the same pitrpose. These tests are proving very useful particularly when they are compared with measurement of survival at temperatures near ambient level.…”