1. Alteration of the Biological Activities of Coagulase-negative Staphylococci Resulted from Storage by Freezing and Freeze-drying(Papers presented at the 35th Annual Meeting, April, 1989, Tokyo)

Abstract

Seventeen strains of 7 species (Staphylococcus epidermidis, S. simulans, S. capitis, S. hominis, S. saprophyticus, S. xylosus, S. warneri) of coagulase-negative staphylococci(CNS) were stored by subculture, freezing and freeze-drying after storage for one year. They were examind by commercial identification kits and the Kloos and Schleifer method. The results showed that strains of Staphylococcus warneri, S. saprophyticus, S. hominis and S. capitis converted to different species of CNS following subculture and freeze-drying. However, no changes were shown with strains of S. xylosus, S. similans and S. epidermidis. The significant changes of biological properties were observed in aerobic acid production from lactose, turanose and N-acetylglucosamine; arginine dihydrolase activity, VP reaction; alkali phosphatase production by α-methylphosphate. Furthermore, the biological properties of the strains of 4 species (S. warneri, S. hominis, S. saprophyticus, S. epidermidis) before storage were compared with strains which had been stored for 64 hours by freezing and freeze-drying by the Kloos and Schleifer method. In these experiments, notable changes were shown in aerobic acid production from N-acetylglucosamine and lactose, and colonial morphology. Major factor of this alteration was assumed to be the effect of the process of freeze-drying.