Liquid Nitrogen Freezing in Microbiological Assay Systems. I. Preservation of Lactobacillus Leichmannii for Direct Use in the Vitamin B12 Assay.
نویسندگان
چکیده
Suspensions of Lactobacillus leichmannii were stored in liquid nitrogen and were used as direct inocula in vitamin B(12) assays. Complete recovery of viable cells was obtained when the suspensions in basal B(12) medium were rapidly frozen by direct immersion into liquid nitrogen and rapidly thawed by agitating the suspensions in a water bath at 40 C. Greater than 90% destruction occurred when the suspensions were in saline. However, both suspensions were usable in the B(12) assay system. Assay results on a number of test materials indicated good correlation between freshly prepared suspensions and frozen suspensions in basal medium stored 3 months. Suspensions in saline stored for 1 year in liquid nitrogen showed no detectable difference from the first day after freezing. Suspensions frozen slowly at the rate of 1 degree per min from 4 to -40 C and subsequently immersed in liquid nitrogen had a longer lag period of growth and were not usable in the 18-hr assay incubation system. A major advantage of a stored inoculum for direct use in a microbiological assay is the reduced day-to-day variation in the inoculum.
منابع مشابه
Liquid Nitrogen Freezing in Microbiological Assay Systems. Ii. Preservation of Sarcina Lutea for Antibiotic Assays.
The storage of Lactobacillus leichmannii in liquid nitrogen for direct use in the vitamin B12 assay was described by Sokolski, Stap)ert, and Ferrer (Appl. Microbiol. 12:327, 1964). This note describes a different ap)proach on treatment of data for stability of a test organism. A stable susl)ension of Sarcina lutea ATCC 9341, a bacterium used in many antibiotic assays, was obtained with storage ...
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The protein precipitates discarded during the extraction process of the Lactobacillus leichmannii vitamin B12 assay have been shown to contain significant amounts of vitamin B12. This loss of vitamin B12 provide a satisfactory explanation for many of the descrepancies between the serum vitamin B12 values obtained by the L. leichmannii method and the radio-isotopic method of Raven et al (1969). ...
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ورودعنوان ژورنال:
- Applied microbiology
دوره 12 شماره
صفحات -
تاریخ انتشار 1964