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Appl Environ Microbiol. 1966 May; 14(3): 456-461
Copyright © 1966 American Society for Microbiology. All Rights Reserved.

Liquid Nitrogen Preservation of Saccharomyces carlsbergensis and its Use in a Rapid Biological Assay of Vitamin B₆ (Pyridoxine)

Control Laboratories, The Upjohn Company, Kalamazoo, Michigan

ABSTRACT

Growth medium as well as freezing menstruum greatly influenced the recovery of Saccharomyces carlsbergensis when it was quickly frozen in liquid nitrogen at — 196 C and quickly thawed at 40 C. Nearly 90% recovery in viability was obtained when S. carlsbergensis was grown in Trypticase Soy Broth and frozen in vitamin B₆ basal assay medium. The growth phase of S. carlsbergensis also influenced recovery after freezing. When S. carlsbergensis was grown in Trypticase Soy Broth and frozen in the broth at the logarithmic-growth phase, only 7% viability was retained; the recovery rate increased to 81% when the culture was frozen in the maximal stationary phase. To have the least possible lag period of growth after thawing, a technique called growth-phase conditioning was introduced. After 1 hr of growth-phase conditioning, S. carlsbergensis was clearly out of lag phase, and budding was observed. A vitamin B₆ microbiological assay with a 6-hr incubation period and with the use of liquid nitrogen-frozen S. carlsbergensis is described.