Preservation of corynebacteriophages by freeze-drying

Abstract

SUMMARYA method of freeze-drying is described by which the activity of a series of corynebacteriophages was maintained over a test period of 30 months, whereas some of these strains became inactive if stored as liquid filtered lysates at 4° C, or frozen and held at − 25° C.

Stability of Staphylococcus aureus Phage ISP after Freeze-Drying (Lyophilization)

“…The level of stabilization afforded by sugars generally depends on their concentration [21]. The results of a number of studies [7], [10], [11], [12] show that various concentrations are optimal for different phages. Therefore, four different concentrations of each of these stabilizers, i.e.…”

“…Thus far, phages have been lyophilized most frequently in normal culture media with addition of gelatin, peptone and some sugars at different concentrations [10], [11], [12], [13]. It is also important to notice that most of the stabilizers used in the studies at the end of the last century with the aim to optimize phage storage conditions, nowadays are not pharmaceutically acceptable any more.…”

“…In our study, all stabilizers were chosen taking into account this particular criterion. In a number of studies [10], [11], [12], sugars, in particular sucrose, proved to be effective cryoprotectants for phage lyophilization and one of the best results were obtained in case of 14 phages active against Corynebacterium spp., lyophilized in the presence of 10% sucrose [10].…”

“…However the longest post-lyophilization storage period thus far studied lasted 20 years [22], indicating that the phage particles remained viable, but without specifying the exact titers before and after lyophilization/storage. In three other studies [10], [23], [24] the storage period also comprises several years (from 2 to 18) during which lyophilized phages showed high stability with a maximum 2 log decrease. In two of these studies [23], [24], skim milk was used as a stabilizer and the third study [10] used more complex media, consisting of 20% peptone +10% sucrose +2% sodium glutamate.…”

“…The methods of lyophilization described in these studies vary significantly with regard to both stabilizers and freeze-drying regimes. The most detailed studies on lyophilization of bacteriophages date back to the 70′s of the last century [10], [11], [12], [13], [14] (Table 1). In this study, we optimized the lyophilization process of the therapeutically important bacteriophage ISP, active against strains of Staphylococcus aureus including MRSA, and explored in more detail the properties of different modern pharmaceutically acceptable stabilizers.…”